Fatty acid composition in the mature milk of Bolivian forager-horticulturalists: controlled comparisons with a US sample

Dietary intake of different ratios of ARA/DHA in early stages and its impact on infant development

Long-chain polyunsaturated fatty acids (LC-PUFAs), arachidonic acid (ARA, 20:4n-6) and docosahexaenoic acid (DHA, 22:6n-3) are essential in the development of infants. ARA and DHA from breast milk or infant formula are the main sources of access for infants to meet their physiological and metabolic needs. The ratio of ARA to DHA in breast milk varies among regions and different lactation stages. Different ratios of ARA and DHA mainly from algal oil, animal fat, fish oil, and microbial oil, are added to infant formula in different regions and infant age ranges. Supplementing with appropriate ratios of ARA and DHA during infancy promotes brain, neural, visual, and other development aspects. In this review, we first introduced the current intake status of ARA and DHA in different locations, lactation stages, and age ranges in breast milk and infant formula. Finally, we discussed the effect of different ratios of ARA and DHA on infant development. This review provided a comprehensive research basis for the nutritional research of infants who consume different ratios of ARA and DHA.

Optimizing ARA and DHA in infant formula: A systematic review of global trends, regional disparities, and considerations for precision nutrition

In the context of precision nutrition, the addition of ARA and DHA in infant formula needs to consider more factors. This study conducted a comprehensive literature review, including 112 relevant Chinese and English articles, to summarize and analyze the global levels of ARA, DHA, and the ARA/DHA ratio in breast milk. The data were correlated with local aquatic products intake and children's IQ. The results indicated that the average level of DHA in breast milk across regions is lower than that of ARA. Variations in DHA content were identified as a primary factor influencing ARA/DHA ratio fluctuations. Breast milk ARA and DHA levels decrease with prolonged lactation periods but increase over the past 22 years. Correlation analysis revealed a significant positive relationship between aquatic products intake and breast milk DHA levels (r = 0.64, p < 0.05). Breast milk DHA levels also showed a significant positive correlation with children's IQ (r = 0.67, p < 0.01). Stable breast milk ARA content did not exhibit significant correlations with aquatic products intake or children's IQ (r = 0, p > 0.05). Among 22 infant formula products available in China, only 5 had ARA levels within the range of breast milk. Most formula products had higher ARA levels than DHA, resulting in ARA/DHA ratios generally exceeding 1. The temporal and spatial variability in breast milk ARA and DHA levels may lead to diverse health outcomes in infants. Therefore, the addition of ARA and DHA in infant formula should consider this variability, including the molecular forms and positional isomerism of the added ARA and DHA. Additionally, considering the impact of different cognitive development tests and infant's gene expression on formula assessment results, there is a need to establish a more comprehensive infant health assessment system to guide the addition of ARA and DHA in formula.

Trans isomeric fatty acids in human milk and their role in infant health and development

It is well known that long chain polyunsaturated fatty acids (LCPUFAs) play an important role in neurodevelopment in the perinatal life. The most important source of these fatty acids is the diet, however, they can also be formed in the human body from their shorter chain precursors, the essential fatty acids. Since the WHO recommends exclusive breastfeeding for the first six months after birth, the exclusive source of these fatty acids for breastfed infants is human milk, which can be influenced by the mother's diet. Unsaturated fatty acids can have either cis or trans configuration double bond in their chain with distinct physiological effects. Cis isomeric unsaturated fatty acids have several beneficial effects, while trans isomers are mostly detrimental, because of their similar structure to saturated fatty acids. Trans fatty acids (TFAs) can be further subdivided into industrial (iTFA) and ruminant-derived trans fatty acids (rTFA). However, the physiological effects of these two TFA subgroups may differ. In adults, dietary intake of iTFA has been linked to atherosclerosis, insulin resistance, obesity, chronic inflammation, and increased development of certain cancers, among other diseases. However, iTFAs can have a negative impact on health not only in adulthood but in childhood too. Results from previous studies have shown that iTFAs have a significant negative effect on LCPUFA levels in the blood of newborns and infants. In addition, iTFAs can affect the growth and development of infants, and animal studies suggest that they might even have lasting negative effects later in life. Since the only source of TFAs in the human body is the diet, the TFA content of breast milk may determine the TFA supply of breastfed infants and thus affect the levels of LCPUFAs important for neurodevelopment and the health of infants. In this review, we aim to provide an overview of the TFA content in human milk available in the literature and their potential effects on infant health and development.

Effects of dietary PUFA patterns and FADS genotype on breast milk PUFAs in Chinese lactating mothers

BACKGROUND

Breastfeeding affects the growth and development of infants, and polyunsaturated fatty acids (PUFAs) play a crucial role in this process. To explore the factors influencing the PUFA concentration in breast milk, we conducted research on two aspects: dietary fatty acid patterns and single nucleotide polymorphisms (SNPs) in maternal fatty acid desaturase genes.

METHODS

Three hundred seventy Chinese Han lactating mothers were recruited. A dietary semi-quantitative food frequency questionnaire (FFQ) was used to investigate the dietary intake of lactating mothers from 22 to 25 days postpartum for 1 year. Meanwhile, breast milk samples were collected from the participants and tested for the concentrations of 8 PUFAs and 10 SNP genotypes. We sought to determine the effect of dietary PUFA patterns and SNPs on breast milk PUFAs. We used SPSS 24.0 statistical software for data analysis. Statistical tests were all bilateral tests, with P < 0.05 as statistically significant.

RESULTS

Under the same dietary background, PUFA contents in breast milk expressed by most major allele homozygote mothers tended to be higher than that expressed by their counterparts who carried minor allele genes. Moreover, under the same gene background, PUFA contents in breast milk expressed by the mother's intake of essential PUFA pattern tended to be higher than that expressed by their counterparts who took the other two kinds of dietary.

CONCLUSIONS

Our study suggests that different genotypes and dietary PUFA patterns affect PUFA levels in breast milk. We recommend that lactating mothers consume enough essential fatty acids to ensure that their infants ingest sufficient PUFAs.

The contributions of parental lactation on offspring development: It's not udder nonsense!

The Developmental Origins of Health and Disease (DOHaD) hypothesis describes how maternal stress exposures experienced during critical periods of perinatal life are linked to altered developmental trajectories in offspring. Perinatal stress also induces changes in lactogenesis, milk volume, maternal care, and the nutritive and non-nutritive components of milk, affecting short and long-term developmental outcomes in offspring. For instance, selective early life stressors shape the contents of milk, including macro/micronutrients, immune components, microbiota, enzymes, hormones, milk-derived extracellular vesicles, and milk microRNAs. In this review, we highlight the contributions of parental lactation to offspring development by examining changes in the composition of breast milk in response to three well-characterized maternal stressors: nutritive stress, immune stress, and psychological stress. We discuss recent findings in human, animal, and in vitro models, their clinical relevance, study limitations, and potential therapeutic significance to improving human health and infant survival. We also discuss the benefits of enrichment methods and support tools that can be used to improve milk quality and volume as well as related developmental outcomes in offspring. Lastly, we use evidence-based primary literature to convey that even though select maternal stressors may modulate lactation biology (by influencing milk composition) depending on the severity and length of exposure, exclusive and/or prolonged milk feeding may attenuate the negative in utero effects of early life stressors and promote healthy developmental trajectories. Overall, scientific evidence supports lactation to be protective against nutritive and immune stressors, but the benefits of lactation in response to psychological stressors need further investigation.

The Impact of Linoleic Acid on Infant Health in the Absence or Presence of DHA in Infant Formulas

Both linoleic acid (LA) and α-linolenic acid (ALA) are essential dietary fatty acids, and a balanced dietary supply of these is of the utmost importance for health. In many countries across the globe, the LA level and LA/ALA ratio in breast milk (BM) are high. For infant formula (IF), the maximum LA level set by authorities (e.g., Codex or China) is 1400 mg LA/100 kcal ≈ 28% of total fatty acid (FA) ≈ 12.6% of energy. The aims of this study are: (1) to provide an overview of polyunsaturated fatty acid (PUFA) levels in BM across the world, and (2) to determine the health impact of different LA levels and LA/ALA ratios in IF by reviewing the published literature in the context of the current regulatory framework. The lipid composition of BM from mothers living in 31 different countries was determined based on a literature review. This review also includes data from infant studies (intervention/cohort) on nutritional needs regarding LA and ALA, safety, and biological effects. The impact of various LA/ALA ratios in IF on DHA status was assessed within the context of the current worldwide regulatory framework including China and the EU. Country averages of LA and ALA in BM range from 8.5-26.9% FA and 0.3-2.65% FA, respectively. The average BM LA level across the world, including mainland China, is below the maximum 28% FA, and no toxicological or long-term safety data are available on LA levels > 28% FA. Although recommended IF LA/ALA ratios range from 5:1 to 15:1, ratios closer to 5:1 seem to promote a higher endogenous synthesis of DHA. However, even those infants fed IF with more optimal LA/ALA ratios do not reach the DHA levels observed in breastfed infants, and the levels of DHA present are not sufficient to have positive effects on vision. Current evidence suggests that there is no benefit to going beyond the maximum LA level of 28% FA in IF. To achieve the DHA levels found in BM, the addition of DHA to IF is necessary, which is in line with regulations in China and the EU. Virtually all intervention studies investigating LA levels and safety were conducted in Western countries in the absence of added DHA. Therefore, well-designed intervention trials in infants across the globe are required to obtain clarity about optimal and safe levels of LA and LA/ALA ratios in IF.

Joint analyses of human milk fatty acids, phospholipids, and choline in association with cognition and temperament traits during the first 6 months of life

Early dietary exposure via human milk nutrients offers a window of opportunity to support cognitive and temperament development. While several studies have focused on associations of few pre-selected human milk nutrients with cognition and temperament, it is highly plausible that human milk nutrients synergistically and jointly support cognitive and behavioral development in early life. We aimed to discern the combined associations of three major classes of human milk nutrients with cognition and temperament during the first 6 months of life when human milk is the primary source of an infant’s nutrition and explore whether there were persistent effects up to 18 months old. The Mullen Scales of Early Learning and Infant Behavior Questionnaires—Revised were used to assess cognition and temperament, respectively, of 54 exclusively/predominantly breastfed infants in the first 6 months of life, whose follow-ups were conducted at 6–9, 9–12, and 12–18 months old. Human milk samples were obtained from the mothers of the participants at less than 6 months of age and analyzed for fatty acids [total monounsaturated fatty acids, polyunsaturated fatty acid, total saturated fatty acid (TSFA), arachidonic acid (ARA), docosahexaenoic acid (DHA), ARA/DHA, omega-6/omega-3 polyunsaturated fatty acids ratio (n-6/n-3)], phospholipids [phosphatidylcholine, phosphatidylethanolamine (PE), phosphatidylinositol (PI), sphingomyelin], and choline [free choline, phosphocholine (PCho), glycerophosphocholine]. Feature selection was performed to select nutrients associated with cognition and temperament. The combined effects of selected nutrients were analyzed using multiple regression. A positive association between the arachidonic acid (ARA) and surgency was observed (p = 0.024). A significant effect of DHA, n-6/n-3, PE, and TSFA concentrations on receptive language (R² = 0.39, p = 0.025) and the elevated ARA, PCho, and PI with increased surgency (R² = 0.43, p = 0.003) was identified, suggesting that DHA and ARA may have distinct roles for temperament and language functions. Furthermore, the exploratory association analyses suggest that the effects of human milk nutrients on R.L. and surgency may persist beyond the first 6 months of life, particularly surgency at 12–18 months (p = 0.002). Our study highlighted that various human milk nutrients work together to support the development of cognition and temperament traits during early infancy.

Changes in Human Milk Fat Globule Composition Throughout Lactation: A Review

There has been a growing interest in understanding how the relative levels of human milk fat globule (MFG) components change over the course of lactation, how they differ between populations, and implications of these changes for the health of the infant. In this article, we describe studies published over the last 30 years which have investigated components of the MFG in term milk, focusing on changes over the course of lactation and highlighting infant and maternal factors that may influence these changes. We then consider how the potential health benefits of some of the milk fat globule membrane (MFGM) components and derived ingredients relate to compositional and functional aspects and how these change throughout lactation. The results show that the concentrations of phospholipids, gangliosides, cholesterol, fatty acids and proteins vary throughout lactation, and such changes are likely to reflect the changing requirements of the growing infant. There is a lack of consistent trends for changes in phospholipids and gangliosides across lactation which may reflect different methodological approaches. Other factors such as maternal diet and geographical location have been shown to influence human MFGM composition. The majority of research on the health benefits of MFGM have been conducted using MFGM ingredients derived from bovine milk, and using animal models which have clearly demonstrated the role of the MFGM in supporting cognitive and immune health of infants at different stages of growth and development.

Macronutrient content and fatty acid composition and their positional distribution in human breast milk from Zhejiang Province, China in different lactation periods

Lactational changes in macronutrient content, lipid profile, fatty acid composition, and positional distribution of human breast milk were investigated in this study. A total of 378 milk samples of six different lactation periods, including 0‒5, 6‒14, 15‒30, 31‒90, 91‒180, and 181‒360 days, were collected cross-sectionally from healthy lactating women in Zhejiang, China. As lactation progressed from 0‒5 to 15‒30 days, the lipid content and the percentages of C10:0, C12:0, C14:0, C18:2n-6, and C18:3n-3 increased significantly, while the protein concentration and the proportions of phospholipids, cholesterols, C16:0, C18:1n-9, C24:1n-9, C20:4n-6, C22:4n-6, C22:5n-3, and C22:6n-3 decreased notably. When lactation was further extended to 181‒360 days, the protein content continued to decrease, and the percentages of C12:0 and C14:0 continued to increase, whereas the levels of other tested nutrients remained stable. Although the triacylglycerol positional distributions of some fatty acids underwent significant lactational variations, C14:0, C16:0, C24:1n-9, C22:4n-6, C22:5n-3, and C22:6n-3 were located mainly at the sn-2 position, while C18:1n-9, C18:2n-6, and C18:3n-3 were primarily distributed at the sn-1,3 positions. Compared with human breast milk reported in Western countries, samples in our study demonstrated higher percentages of C18:2n-6, C18:3n-3, C20:4n-6, and C22:6n-3, but lower proportions of C12:0, C14:0, and C18:1n-9. The results from this study indicated a nutritional composition different from that of the Western countries and may provide useful data for the development of infant formulas closer to Chinese breast milk in terms of the fatty acid composition and its specified positional distribution on triglyceride structure.

Chinese Breast Milk Fat Composition and Its Associated Dietary Factors: A Pilot Study on Lactating Mothers in Beijing

Regional differences were found in breast milk composition. This study intended to profile the composition of fatty acid (FA) and triacylglycerol (TAG) in Chinese breast milk and to explore its association with maternal diet. Breast milk samples and data of 52 lactating women at 60–90 days postpartum were collected. The FA composition was measured using gas chromatography–flame ionization detection (GC-FID), and the TAG profile was detected by an ultra-performance liquid chromatography system, coupled with accurate-mass quadrupole time-of-flight mass spectrometer. A semi-quantitative food intake frequency questionnaire and a one-time 24-h dietary recall were used to evaluate the previous month's and the short-term dietary intake, including dietary patterns, food groups, and nutrients. Oleic–palmitic–linoleic (OPL) is the most predominant TAG within the Chinese human milk, followed by oleic–palmitic–oleic (OPO), with an average OPL-to-OPO ratio of 1.35. Linoleic acid (LA) and oleic acid (OA) accounted for 23.9 and 32.0% of the total FAs, respectively. Among the food groups consumed during the preceding month, LA content was positively associated with the consumption of soybeans and soybean products (r = 0.311, p = 0.030), whereas a negative correlation was identified with seafood consumption (r = −0.302, p = 0.030). Negative correlations were found between the OA content and the consumption of soybeans and soybean products (r = −0.363, p = 0.009), livestock and poultry meat (r = −0.375, p = 0.006), nuts (r = −0.305, p = 0.028), as well as cooking oil (r = −0.445, p = 0.001). No significant associations were identified between the LA and OA contents and the dietary patterns. This study confirmed a high OPL level in Chinese breast milk and revealed associations of FAs with maternal dietary intake.

The Indigenous South American Tsimane Exhibit Relatively Modest Decrease in Brain Volume With Age Despite High Systemic Inflammation

Brain atrophy is correlated with risk of cognitive impairment, functional decline, and dementia. Despite a high infectious disease burden, Tsimane forager-horticulturists of Bolivia have the lowest prevalence of coronary atherosclerosis of any studied population and present few cardiovascular disease (CVD) risk factors despite a high burden of infections and therefore inflammation. This study (a) examines the statistical association between brain volume (BV) and age for Tsimane and (b) compares this association to that of 3 industrialized populations in the United States and Europe. This cohort-based panel study enrolled 746 participants aged 40-94 (396 males), from whom computed tomography (CT) head scans were acquired. BV and intracranial volume (ICV) were calculated from automatic head CT segmentations. The linear regression coefficient estimate β^T of the Tsimane (T), describing the relationship between age (predictor) and BV (response, as a percentage of ICV), was calculated for the pooled sample (including both sexes) and for each sex. β^T was compared to the corresponding regression coefficient estimate β^R of samples from the industrialized reference (R) countries. For all comparisons, the null hypothesis β T = β R was rejected both for the combined samples of males and females, as well as separately for each sex. Our results indicate that the Tsimane exhibit a significantly slower decrease in BV with age than populations in the United States and Europe. Such reduced rates of BV decrease, together with a subsistence lifestyle and low CVD risk, may protect brain health despite considerable chronic inflammation related to infectious burden.

Was facial width-to-height ratio subject to sexual selection pressures? A life course approach

Sexual selection researchers have traditionally focused on adult sex differences; however, the schedule and pattern of sex-specific ontogeny can provide insights unobtainable from an exclusive focus on adults. Recently, it has been debated whether facial width-to-height ratio (fWHR; bi-zygomatic breadth divided by midface height) is a human secondary sexual characteristic (SSC). Here, we review current evidence, then address this debate using ontogenetic evidence, which has been under-explored in fWHR research. Facial measurements were collected from 3D surface images of males and females aged 3 to 40 (Study 1; US European-descent, n = 2449), and from 2D photographs of males and females aged 7 to 21 (Study 2; Bolivian Tsimane, n = 179), which were used to calculate three fWHR variants (which we call fWHRnasion, fWHRstomion, and fWHRbrow) and two other common facial masculinity ratios (facial width-to-lower-face-height ratio, fWHRlower, and cheekbone prominence). We test whether the observed pattern of facial development exhibits patterns indicative of SSCs, i.e., differential adolescent growth in either male or female facial morphology leading to an adult sex difference. Results showed that only fWHRlower exhibited both adult sex differences as well as the classic pattern of ontogeny for SSCs-greater lower-face growth in male adolescents relative to females. fWHRbrow was significantly wider among both pre- and post-pubertal males in the Bolivian Tsimane sample; post-hoc analyses revealed that the effect was driven by large sex differences in brow height, with females having higher placed brows than males across ages. In both samples, all fWHR measures were inversely associated with age; that is, human facial growth is characterized by greater relative elongation in the mid-face and lower face relative to facial width. This trend continues even into middle adulthood. BMI was also a positive predictor of most of the ratios across ages, with greater BMI associated with wider faces. Researchers collecting data on fWHR should target fWHRlower and fWHRbrow and should control for both age and BMI. Researchers should also compare ratio approaches with multivariate techniques, such as geometric morphometrics, to examine whether the latter have greater utility for understanding the evolution of facial sexual dimorphism.

Temporal Changes in Breast Milk Fatty Acids Contents: A Case Study of Malay Breastfeeding Women

The composition of human breast milk changes in the first two months of life, adapting itself to the evolving needs of the growing new-born. Lipids in milk are a source of energy, essential fatty acids (FA), fat-soluble vitamins, and vital bioactive components. Information on breast milk FA of Malaysian lactating women is scarce. Based on convenience sampling, a total of 20 Malay breastfeeding women who fulfilled the inclusion criteria were recruited. Breast milk was collected three times from each subject at consecutive intervals of 2–3 weeks apart. A total of 60 breast milk samples were collected and classified into “transitional milk” (n = 8), “early milk” (n = 26) and “mature milk” (n = 26). All milk samples were air freighted to University of Groningen, Netherlands for analysis. The dominant breast milk FA were oleic acid, constituting 33% of total fatty acids, followed by palmitic acid (26%). Both these FA and the essential FA, linoleic acid (10%) and alpha-linolenic acid (0.4%), showed no significant changes from transitional to mature milk. Breast milk ratio of n-6:n-3 polyunsaturated fatty acids (PUFA) was comparatively high, exceeding 10 throughout the lactation period, suggesting a healthier balance of PUFA intake is needed in pregnancy and at postpartum.

Rapidly declining body temperature in a tropical human population

Normal human body temperature (BT) has long been considered to be 37.0°C. Yet, BTs have declined over the past two centuries in the United States, coinciding with reductions in infection and increasing life expectancy. The generality of and reasons behind this phenomenon have not yet been well studied. Here, we show that Bolivian forager-farmers (n = 17,958 observations of 5481 adults age 15+ years) inhabiting a pathogen-rich environment exhibited higher BT when first examined in the early 21st century (~37.0°C). BT subsequently declined by ~0.05°C/year over 16 years of socioeconomic and epidemiological change to ~36.5°C by 2018. As predicted, infections and other lifestyle factors explain variation in BT, but these factors do not account for the temporal declines. Changes in physical activity, body composition, antibiotic usage, and thermal environment are potential causes of the temporal decline.

The Influence of Markets on the Nutrition Transition of Hunter-Gatherers: Lessons from the Western Amazon

For many centuries, hunter-gatherer societies relied on subsistence practices and traditional diets. However, forces of globalization have increased market involvement, thereby fueling the nutrition transition of hunter-gatherer societies. We review the academic literature on market involvement of hunter-gatherer societies in the Western Amazon and its consequences on diet, health and well-being. First, we elaborate on four main determinants of market involvement (accessibility, monetary income, wild meat trade and social capital), showing how each determinant draws individuals toward or away from markets. Thereafter, we discuss how these determinants alter diet, health and well-being. Our results add to the understanding of the complex relations between market involvement, dietary change, health and well-being of indigenous societies. Furthermore, they bring to light that additional research is needed on the topic to support decision-makers and help preserve indigenous values.

Impact of Infant and Maternal Factors on Energy and Macronutrient Composition of Human Milk

The present study investigates the influence of selected infant and maternal factors on the energy and macronutrient composition of mature human milk (HM). The study enrolled 77 mothers at 4-8 weeks postpartum. Each mother provided 1 sample of HM. Each extracted HM sample was formed by mixing four subsamples of HM, each of which were obtained in one predefined 6-h periods of the day. Among maternal factors, the analysis included: anthropometric data before and after pregnancy; weight gain in pregnancy; body composition, assessed using the Maltron BioScan 920-II to analyze bioimpedance; and dietary intake, assessed with three-day dietary records. Among the neonatal factors, birth weight and length, number of daily feedings and type of delivery were included. The composition of HM, including energy content, protein, fat and carbohydrate concentrations, was analyzed using the Miris human milk analyzer. Pearson's and Spearman's correlation coefficients and multivariable logistic regression models were used to analyze the association between the selected maternal and infant factors and HM milk composition. It was found that total protein content of HM was correlated with pre-pregnancy BMI (Spearman rho = 0.238; p = 0.037), current lean body mass (Spearman rho = -0.293, p = 0.01) and total water content (Spearman rho = -0.315, p = 0.005). Carbohydrates were the only macronutrients whose composition was significantly affected by the infant factors. It was reported that higher carbohydrate content was associated with male sex (OR = 4.52, p = 0.049). Our results show that maternal and infant factors, especially maternal pre-pregnancy and current nutritional status and infant sex, interact and affect HM composition, suggesting that macronutrient and energy content in HM may be determined in pregnancy and may have unique compositional profile for every mother-infant dyad.

Lipidome analysis of milk composition in humans, monkeys, bovids, and pigs

Background

Lipids contained in milk are an essential source of energy and structural materials for a growing neonate. Furthermore, lipids’ long-chain unsaturated fatty acid residues can directly participate in neonatal tissue formation. Here, we used untargeted mass spectrometric measurements to assess milk lipid composition in seven mammalian species: humans, two macaque species, cows, goats, yaks, and pigs.

Results

Analysis of the main milk lipid class, triacylglycerides (TAGs), revealed species-specific quantitative differences in the composition of fatty acid residues for each of seven species. Overall, differences in milk lipid composition reflect evolutionary distances among species, with each species group demonstrating specific lipidome features. Among them, human milk contained more medium and long-chain unsaturated fatty acids compared to other species, while pig milk was the most distinct, featuring the highest proportion of long-chain polyunsaturated fatty acids.

Conclusions

We show that milk lipidome composition is dynamic across mammalian species, changed extensively in pigs, and contains features particular to humans.

Effects of energy and essential fatty acids content in breast milk on infant's head dimensions

OBJECTIVES

Essential fatty acids (EFA), including linoleic acid (LA) and alpha-linolenic acid (ALA), are indispensable for proper brain growth especially in the first months after birth when it develops most rapidly. Since fats, especially EFA, in breast milk are highly variable between mothers, we indirectly examined whether milk energy, LA and ALA content in breast milk affect volume and shape of the infant's head.

METHODS

The study encompassed 60 mothers and their healthy term-born infants between the third and sixth month of lactation. The percentage of macronutrients and dry matter in human milk samples was assessed using Fourier-transform infrared spectroscopy (FTIR), and LA and ALA concentrations in breast milk were determined using gas chromatography (GC). Infant head measurements were taken using standard anthropometric equipment and methods.

RESULTS

LA content in breast milk was found to be positively associated with head volume in boys. Furthermore, ALA content was positively associated with the head height-to-length ratio thus with more arched head in infants irrespective of sex. No relationship was found between milk energy content in mothers' milk and infant head dimensions.

CONCLUSIONS

This is the first study to demonstrate a relationship between EFA concentration in human milk and infant head dimensions. Given that LA and ALA in human milk are variable in women and due to the extremely rapid growth of nerve tissue in the first months of life, adequate supply of EFA in breast milk should attract the attention of public health sciences.

Influence of Maternal Milk on the Neonatal Intestinal Microbiome

The intestinal microbiome plays an important role in maintaining health throughout life. The microbiota develops progressively after birth and is influenced by many factors, including the mode of delivery, antibiotics, and diet. Maternal milk is critically important to the development of the neonatal intestinal microbiota. Different bioactive components of milk, such as human milk oligosaccharides, lactoferrin, and secretory immunoglobulins, modify the composition of the neonatal microbiota. In this article, we review the role of each of these maternal milk-derived bioactive factors on the microbiota and how this modulation of intestinal bacteria shapes health, and disease.

Sexually Dimorphic Associations between Maternal Factors and Human Milk Hormonal Concentrations

While human milk composition is characterised by marked dynamicity, we are far from having a clear picture of what factors drive this variation. Hormones in human milk are known to vary according to specific maternal phenotypes, but limited evidence shows the infant also has a role in determining milk composition. The present study aimed to investigate the interplay between maternal and infant characteristics in relation to human milk hormonal profile. In total, 501 human milk samples from mothers recruited in the Finnish STEPS cohort study (Steps to the healthy development) were analysed. Pre-pregnancy and pregnancy maternal data, socioeconomic status and infant characteristics at birth were collated. Leptin, adiponectin, insulin-like growth factor-1 and cyclic Glycine-Proline in milk were measured. Multivariate analysis of variance (MANOVA) and linear regression were utilised for statistical analysis. Sex-specific interactions with maternal factors were observed, as the infant sex mediated associations between gestational diabetes and milk adiponectin (p = 0.031), birth-mode and total protein (p = 0.003), maternal education and insulin-like growth factor-1: cyclic Glycine-Proline ratio (p = 0.035). Our results suggest that changes in human milk composition are associated with interactions between maternal and infant characteristics and pathophysiological factors. Future work should expand on these findings and further explore the link between hormonal profiles in human milk and infant outcomes.

Dietary Restrictions and Nutrition in the Prevention and Treatment of Cardiovascular Disease

Cardiovascular disease (CVD) is the leading cause of death in many developed countries and remains one of the major diseases strongly affected by the diet. Nutrition can affect CVD directly by contributing to the accumulation of vascular plaques and also indirectly by regulating the rate of aging. This review summarizes research on nutrition and CVD incidence based on a multipillar system that includes basic research focused on aging, epidemiological studies, clinical studies, and studies of centenarians. The relevant research linking nutrition and CVD with focus on macronutrients and aging will be highlighted. We will review some of the most relevant studies on nutrition and CVD treatment, also focusing on interventions known to delay aging. We will discuss both everyday dietary compositions, as well as intermittent and periodic fasting interventions with the potential to prevent and treat CVD.

Relationship between the lipid composition of maternal plasma and infant plasma through breast milk

INTRODUCTION

This study was motivated by the report that infant development correlates with particular lipids in infant plasma.

OBJECTIVE

The hypothesis was that the abundance of these candidate biomarkers is influenced by the dietary intake of the infant.

METHODS

A cohort of 30 exclusively-breastfeeding mother-infant pairs from a small region of West Africa was used for this observational study. Plasma and milk from the mother and plasma from her infant were collected within 24 h, 3 months post partum. The lipid, sterol and glyceride composition was surveyed using direct infusion MS in positive and negative ion modes. Analysis employed a combination of univariate and multivariate tests.

RESULTS

The lipid profiles of mother and infant plasma samples are similar but distinguishable, and both are distinct from milk. Phosphatidylcholines (PC), cholesteryl esters (CEs) and cholesterol were more abundant in mothers with respect to their infants, e.g. PC(34:1) was 5.66% in mothers but 3.61% in infants (p = 3.60 × 10^-10), CE(18:2) was 8.05% in mothers but 5.18% in infants (p = 1.37 × 10^-11) whilst TGs were lower in mothers with respect to their infants, e.g. TG(52:2) was 2.74% in mothers and 4.23% in infants (p = 1.63 × 10^-05). A latent structure model showed that four lipids in infant plasma previously shown to be biomarkers clustered with cholesteryl esters in the maternal circulation.

CONCLUSION

This study found evidence that the abundance of individual lipid isoforms associated with infant development are associated with the abundance of individual molecular species in the mother's circulation.

Nutrition transition in 2 lowland Bolivian subsistence populations

Background

Traditional diets are often credited for the robust cardiometabolic health of subsistence populations. Yet, rural subsistence populations are undergoing nutrition transitions that have been linked to the increase in chronic noncommunicable diseases. Few studies have presented detailed dietary estimates in transitioning populations.

Objectives

We aimed to 1) characterize and compare dietary profiles of 2 neighboring subsistence populations in Bolivia who vary in market integration and 2) identify dietary factors contributing to low cardiovascular disease risk.

Design

We used a mixed longitudinal design to estimate nutrient intake via 24-h recall and dietary questionnaires among 1299 Tsimane (aged 30-91 y) and 229 Moseten (aged 30-84 y) men and women. We constructed population-level estimates of energy intake, dietary diversity, and nutrient shortfalls and analyzed dietary changes over time and space using multilevel models. Last, we compared Tsimane and Moseten dietary profiles with those of Americans (NHANES).

Results

The Tsimane diet was characterized by high energy (2422-2736 kcal/d), carbohydrate (376-423 g/d), and protein (119-139 g/d) intakes; low fat intake (40-46 g/d); and low dietary diversity relative to the average US diet. Most calories (64%) were derived from complex carbohydrates. Total energy and carbohydrate intake increased significantly during the 5-y study, particularly in villages near market towns. Tsimane consumption of food additives (lard, oil, sugar, salt) increased significantly [sugar (15.8 g ⋅ person-1 ⋅ d-1) and oil (4.9 mL ⋅ person-1 ⋅ d-1)] between 2010 and 2015. The more-acculturated Moseten consumed substantially more sugar (by 343%) and oil (by 535%) than the Tsimane.

Conclusions

A high-energy diet rich in complex carbohydrates is associated with low cardiovascular disease risk when coupled with a physically active lifestyle. A transition away from a high-fiber and low-fat, low-salt, and low-processed-sugar diet is a salient health risk for transitioning populations. Evidence of a nutrition transition in Bolivia parallels trends of increasing body fat and body mass index, which suggests that a low prevalence of cardiovascular disease may not persist.

Variation among populations in the immune protein composition of mother's milk reflects subsistence pattern

LAY SUMMARY

Adaptive immune proteins in mothers' milk are more variable than innate immune proteins across populations and subsistence strategies. These results suggest that the immune defenses in milk are shaped by a mother's environment throughout her life.

BACKGROUND AND OBJECTIVES

Mother's milk contains immune proteins that play critical roles in protecting the infant from infection and priming the infant's developing immune system during early life. The composition of these molecules in milk, particularly the acquired immune proteins, is thought to reflect a mother's immunological exposures throughout her life. In this study, we examine the composition of innate and acquired immune proteins in milk across seven populations with diverse disease and cultural ecologies.

METHODOLOGY

Milk samples (n = 164) were collected in Argentina, Bolivia, Nepal, Namibia, Philippines, Poland and the USA. Populations were classified as having one of four subsistence patterns: urban-industrialism, rural-shop, horticulturalist-forager or agro-pastoralism. Milk innate (lactalbumin, lactoferrin and lysozyme) and acquired (Secretory IgA, IgG and IgM) protein concentrations were determined using triple-quadrupole mass spectrometry.

RESULTS

Both innate and acquired immune protein composition in milk varied among populations, though the acquired immune protein composition of milk differed more among populations. Populations living in closer geographic proximity or having similar subsistence strategies (e.g. agro-pastoralists from Nepal and Namibia) had more similar milk immune protein compositions. Agro-pastoralists had different milk innate immune protein composition from horticulturalist-foragers and urban-industrialists. Acquired immune protein composition differed among all subsistence strategies except horticulturist-foragers and rural-shop.

CONCLUSIONS AND IMPLICATIONS

Our results reveal fundamental variation in milk composition that has not been previously explored in human milk research. Further study is needed to understand what specific aspects of the local environment influence milk composition and the effects this variation may have on infant health outcomes.

Child nutritional status among births exceeding ideal family size in a high fertility population

Ideal family size (IFS) is measured in social surveys to indicate unmet need for contraception and impending shifts in fertility behaviour. Whether exceeding IFS affects parental behaviour in ways that result in lower investments in child nutrition, well-being, and educational attainment is not known. This study examines parental IFS and the association between exceeding stated ideals and child nutritional status in a high-fertility, high-mortality population in the Bolivian Amazon. Height-for-age z-scores, weight-for-age z-scores, weight-for-height z-scores, stunting, haemoglobin, and anaemia status in 638 children aged 0-5 years are predicted as a function of birth order in relation to parental IFS, adjusting for household characteristics and mother and child random effects. Children of birth orders above paternal IFS experience higher weight-for-age z-scores when living further away from the market town of San Borja, consistent with underlying motivations for higher IFS and lower human capital investment in children in more remote areas (β = .009, p = .027). Overall, we find no statistical evidence that birth orders in excess of parental ideals are associated with compromised child nutrition below age 2, a period of intensive breastfeeding in this population. Despite a vulnerability to nutritional deficiencies postweaning for children age 2-5, there was no association between birth order in excess of parental ideals and lower nutritional status. Further studies examining this association at various stages of the fertility transition will elucidate whether reported ideal or optimal family sizes are flexible as trade-offs between quality and quantity of children shift during the transition to lower fertility.

Sex-Specific Human Milk Composition: The Role of Infant Sex in Determining Early Life Nutrition

Male and female infants respond differentially to environmental stimuli, with different growth and neurodevelopmental trajectories. Male infants are more likely to be disadvantaged when subjected to adversity and show a higher risk of perinatal complications. However, the underlying causes of this sex-bias are not well defined and optimising the early life nutritional care may be necessary to minimise the “male disadvantage” that may be experienced early in life. Experimental models have demonstrated that animal milk composition differs according to offspring sex, suggesting that the tailoring of early life nutrition may be one mechanism to maximise health protection and development to infants of both sexes. However, evidence for a sex-specificity in human milk composition is limited and conflicting, with studies documenting higher milk energy content for either male or female infants. These data show sex differences, however, there has been limited compositional analysis of the current data nor strategies proposed for how sex-specific compositional differences in early life nutrition may be used to improve infant health. The present narrative review highlights that an improved understanding of sex-specific human milk composition is essential for promoting optimal infant growth and development.

Dietary patterns affect maternal macronutrient intake levels and the fatty acid profile of breast milk in lactating Chinese mothers

OBJECTIVES

Fatty acids (FA) in human milk play an important role in meeting the nutritional demands and promoting the growth and development of breastfeeding infants. Breast milk FA is sensitive to maternal dietary habits, and dietary patterns are better used to explain the effect of diet on FA. Few studies have examined the association between maternal dietary patterns and the FA components of breast milk in developing countries. In this study, we aimed to determine whether dietary patterns affect the FA profile of breast milk in lactating Chinese mothers with the overall goal to optimize the management of infant feeding.

METHODS

A total of 274 lactating women ranging from 22 d to 6 mo postpartum were included, and samples of their breast milk were collected together with completed questionnaires. Using a principal component analysis, four dietary patterns were identified in a rotated component matrix. FA profiles were detected using capillary gas chromatography and presented as the percentage by weight of total FA.

RESULTS

Maternal intake of energy, carbohydrates, and proteins showed differences between the different dietary patterns. In addition, there were significant differences in the total proportions of saturated, polyunsaturated, and ω-6 polyunsaturated fatty acids in breast milk among the four patterns (P < 0.001; P = 0.025; P = 0.038, respectively).

CONCLUSIONS

The results demonstrate that maternal dietary patterns can affect macronutrient intake levels and milk FA profiles in lactating Chinese women. These results are of great significance in understanding how a maternal diet can both improve maternal macronutrient intake and the FA nutritional status of breast milk.

Parental hormones are associated with crop loss and family sickness following catastrophic flooding in lowland Bolivia

The physiology of fatherhood is a growing field of study, and variability in hormonal mediators of reproductive effort (e.g. testosterone, cortisol) can predict variability in paternal investment. Studies often find that lower testosterone levels are associated with increased paternal investment, though most studies are conducted under relatively stable ecological conditions. In this paper, we examine parental physiological correlates of crop loss and family health problems among Tsimane forager-horticulturalists following a catastrophic flood in lowland Bolivia. Immediately after a devastating 2014 flood that impacted >75% of Tsimane communities, we conducted structured interviews examining crop losses and morbidity, and collected saliva specimens from 421 parents (n = 292 households) to analyze cortisol and testosterone. Over 98% of interviewees reported horticultural losses, with the average family losing 88% of their crops, while 80% of families reported flood-induced injuries or illnesses. Controlling for age, body mass index, and time of specimen collection, men's testosterone was negatively associated with both absolute cropland losses (Std. β = -0.16, p = 0.037), and percent of cropland lost (Std. β = -0.16, p = 0.040). Female testosterone was not associated with crop losses. Using the same control variables, both male and female cortisol was negatively associated with a composite measure of child health burden (fathers: Std. β = -0.34, p < 0.001; mothers: Std. β = -0.23, p = 0.037). These results are discussed in the cultural context of a strong sexual division of labor among Tsimane; we highlight the physiological and psychosocial costs of experiencing a natural disaster, especially for paternal caregivers in a nutritionally and pathogenically stressed subsistence population where cultigens provide the majority of calories in the diet.

Changes in fatty acid composition of human milk over lactation stages and relationship with dietary intake in Chinese women

Breast milk samples and 24-hour food records were obtained from lactating mothers on day 1 (colostrum), day 14 (transitional milk) and day 42 (mature milk) from Hangzhou (n = 202), Lanzhou (n = 133) and Beijing (n = 142), China. Fatty acid methyl esters were prepared by standard methods, separated and quantified by gas chromatography. We aimed to investigate the fatty acid composition (% of total fatty acid) in human milk of three lactating stages from three regions in China and the relationship with maternal dietary intake during lactation. Present results showed that the fatty acid composition of breast milk varied with lactating period and geographical regions in China. In all the milk samples, the total saturated fatty acid (SFA) remained stable. However, C10:0 and C12:0 increased over the lactation period, total monounsaturated fatty acid (MUFA) significantly increased from colostrum (34.50%) to transitional milk (37.06%), and total polyunsaturated fatty acid (PUFA) showed its highest percentage in colostrum (29.58%). In particular, C22:6n-3 and C22:5n-3 were lowest in mature milk (0.38% and 0.41%, respectively), and C18:3n-3 (1.83%) was lowest in colostrum. There were significant differences among the three regions in total MUFA and PUFA in breast milk. The Hangzhou samples had the lowest C18:1n-9 and highest C22:6n-3. Additionally, C22:6n-3, total PUFA and n-3 PUFA were lowest in the Lanzhou samples. Different dietary habits were largely the drivers behind the different fatty acid profiles among the three regions.

Information transmission and the oral tradition: Evidence of a late-life service niche for Tsimane Amerindians

Storytelling can affect wellbeing and fitness by transmitting information and reinforcing cultural codes of conduct. Despite their potential importance, the development and timing of storytelling skills, and the transmission of story knowledge have received minimal attention in studies of subsistence societies that more often focus on food production skills. Here we examine how storytelling and patterns of information transmission among Tsimane forager-horticulturalists are predicted by the changing age profiles of storytellers' abilities and accumulated experience. We find that storytelling skills are most developed among older adults who demonstrate superior knowledge of traditional stories and who report telling stories most. We find that the important information transmitted via storytelling typically flows from older to younger generations, and stories are primarily learned from older same-sex relatives, especially grandparents. Our findings suggest that the oral tradition provides a specialized late-life service niche for Tsimane adults who have accumulated important experience and knowledge relevant to foraging and sociality, but have lost comparative advantage in other productive domains. These findings may help extend our understanding of the evolved human life history by illustrating how changes in embodied capital predict the development of information transmission services in a forager-horticulturalist economy.

Concentrations of trace elements in human milk: Comparisons among women in Argentina, Namibia, Poland, and the United States

Human milk contains essential micronutrients for growth and development during early life. Environmental pollutants, such as potentially toxic metals, can also be transferred to the infant through human milk. These elements have been well-studied, but changing diets and environments and advances in laboratory technology require re-examining these elements in a variety of settings. The aim of this study was to characterize the concentrations of essential and toxic metals in human milk from four diverse populations. Human milk samples (n = 70) were collected in Argentina (n = 21), Namibia (n = 6), Poland (n = 23), and the United States (n = 20) using a standardized mid-feed collection procedure. Milk concentrations of calcium, zinc, iron, copper, manganese, lead, arsenic, and cadmium were determined using inductively coupled plasma mass spectrometry (ICP-MS). We used standard multiple linear regression models to evaluate differences among populations, while including infant age, infant sex, and maternal parity status (multiparous or primiparous) as covariates. Concentrations of all elements, except zinc, varied across populations after controlling for infant age, infant sex, and maternal parity. Calcium and magnesium showed more differences across populations than iron or copper. There were no significant differences among population in zinc concentrations. Mean concentrations of lead, but not arsenic, were low compared to recently published values from other populations. The concentrations of trace elements in human milk are variable among populations. Limitations due to small sample sizes and environmental contamination of some samples prevent us from drawing robust conclusions about the causes of these differences.

Toxicoanthropology: Phthalate exposure in relation to market access in a remote forager-horticulturalist population

Phthalates are a class of plasticizing chemicals produced in high volume and widely found in consumer products. Evidence suggests that phthalates may have non-monotonic effects on reproductive hormone activity. With exposure to phthalates virtually ubiquitous among industrialized populations, identifying unexposed and/or minimally exposed human populations is essential for understanding the effects of low level exposures. Our primary objective was to quantify urinary phthalate metabolite concentrations in the Tsimane', a remote population of Bolivian forager-horticulturalists. Our secondary objectives were to determine if phthalate metabolite concentrations vary in relation to access to market goods; and to explore relationships between phthalate and reproductive hormone metabolite concentrations. Given that phthalate exposure is of particular concern during fetal development, we focused on reproductive age women in the current analyses. Phthalate metabolites were assayed in urine samples from 59 naturally cycling, reproductive age Tsimane' women. Market access was assessed as: (1) distance from residence to the largest nearby town (San Borja, Bolivia) and (2) Spanish fluency. Urinary reproductive hormone metabolite concentrations were quantified using enzyme immunoassays. We fit linear models to examine: (1) predictors of phthalate exposure; and (2) relationships between urinary phthalate and reproductive hormone metabolite concentrations. Eight phthalate metabolites were detectable in at least 75% of samples. Median concentrations were up to an order of magnitude lower than industrialized populations. Proximity to San Borja and Spanish fluency were strong predictors of exposure. In exploratory analyses, the sum of the di-2-ethylhexyl phthalate metabolites (∑DEHP) and Mono-isobutyl phthalate (MiBP) were significantly associated with altered concentrations of urinary reproductive hormone metabolites. Remote, subsistence populations, like the Tsimane', offer a unique window into the health effects of endocrine active compounds because: (1) exposures are low and likely to be first generation; (2) a natural fertility lifestyle allows for exploration of reproductive effects; and (3) ever-increasing globalization will result in increasing exposure in the next decade.

Reducing the maternal dietary intake of indigestible and slowly absorbed short-chain carbohydrates is associated with improved infantile colic: a proof-of-concept study

BACKGROUND

To investigate if a low fermentable oligo-, di- and mono-saccharides and polyols (FODMAP) diet consumed by breastfeeding mothers may be associated with reduced symptoms of infantile colic.

METHODS

Exclusively breastfeeding mothers and their typically-developing healthy infants who met the Wessel Criteria for infantile colic were recruited from the community, to this single-blind, open-label, interventional study. After a 3-day qualifying period, mothers were provided a low FODMAP 7-day diet. On days 5, 6 and 7 mothers completed a Baby Day Diary. At baseline and at the end of the 7-day dietary intervention, breast milk was analysed for FODMAP content and infant faecal samples for pH.

RESULTS

Eighteen breastfeeding mothers (aged 27-40 years) adhered (100%) to the low FODMAP diet. Infants were of gestational age 37-40.3 weeks and aged 2-17 weeks. At entry, crying durations were a mean [95% CI] of 142 [106-61] min and fell by 52 [178-120] min (P = 0.005; ancova). Combined crying-fussing durations fell by 73 [301-223] min (n = 13; P = 0.007), as did crying episodes (P = 0.01) and fussing durations (P = 0.011). Infant sleeping, feeding, or awake-and-content durations did not change. Infant faecal pH did not change. Breast milk lactose content was stable and other known FODMAPs were not detected. At end of study, mothers reported their baby 'is much more content' and 'can be put down without crying'.

CONCLUSIONS

Maternal low FODMAP diet may be associated with a reduction in infant colic symptoms. A randomized controlled study is warranted to determine if a maternal low FODMAP diet is effective in reducing symptoms.

Coronary atherosclerosis in indigenous South American Tsimane: a cross-sectional cohort study

BACKGROUND

Conventional coronary artery disease risk factors might potentially explain at least 90% of the attributable risk of coronary artery disease. To better understand the association between the pre-industrial lifestyle and low prevalence of coronary artery disease risk factors, we examined the Tsimane, a Bolivian population living a subsistence lifestyle of hunting, gathering, fishing, and farming with few cardiovascular risk factors, but high infectious inflammatory burden.

METHODS

We did a cross-sectional cohort study including all individuals who self-identified as Tsimane and who were aged 40 years or older. Coronary atherosclerosis was assessed by coronary artery calcium (CAC) scoring done with non-contrast CT in Tsimane adults. We assessed the difference between the Tsimane and 6814 participants from the Multi-Ethnic Study of Atherosclerosis (MESA). CAC scores higher than 100 were considered representative of significant atherosclerotic disease. Tsimane blood lipid and inflammatory biomarkers were obtained at the time of scanning, and in some patients, longitudinally.

FINDINGS

Between July 2, 2014, and Sept 10, 2015, 705 individuals, who had data available for analysis, were included in this study. 596 (85%) of 705 Tsimane had no CAC, 89 (13%) had CAC scores of 1-100, and 20 (3%) had CAC scores higher than 100. For individuals older than age 75 years, 31 (65%) Tsimane presented with a CAC score of 0, and only four (8%) had CAC scores of 100 or more, a five-fold lower prevalence than industrialised populations (p≤0·0001 for all age categories of MESA). Mean LDL and HDL cholesterol concentrations were 2·35 mmol/L (91 mg/dL) and 1·0 mmol/L (39·5 mg/dL), respectively; obesity, hypertension, high blood sugar, and regular cigarette smoking were rare. High-sensitivity C-reactive protein was elevated beyond the clinical cutoff of 3·0 mg/dL in 360 (51%) Tsimane participants.

INTERPRETATION

Despite a high infectious inflammatory burden, the Tsimane, a forager-horticulturalist population of the Bolivian Amazon with few coronary artery disease risk factors, have the lowest reported levels of coronary artery disease of any population recorded to date. These findings suggest that coronary atherosclerosis can be avoided in most people by achieving a lifetime with very low LDL, low blood pressure, low glucose, normal body-mass index, no smoking, and plenty of physical activity. The relative contributions of each are still to be determined.

FUNDING

National Institute on Aging, National Institutes of Health; St Luke's Hospital of Kansas City; and Paleocardiology Foundation.

The Tsimane Health and Life History Project: Integrating anthropology and biomedicine

The Tsimane Health and Life History Project, an integrated bio-behavioral study of the human life course, is designed to test competing hypotheses of human life-history evolution. One aim is to understand the bidirectional connections between life history and social behavior in a high-fertility, kin-based context lacking amenities of modern urban life (e.g. sanitation, banks, electricity). Another aim is to understand how a high pathogen burden influences health and well-being during development and adulthood. A third aim addresses how modernization shapes human life histories and sociality. Here we outline the project's goals, history, and main findings since its inception in 2002. We reflect on the implications of current findings and highlight the need for more coordinated ethnographic and biomedical study of contemporary nonindustrial populations to address broad questions that can situate evolutionary anthropology in a key position within the social and life sciences.

Horticultural activity predicts later localized limb status in a contemporary pre-industrial population

OBJECTIVES

Modern humans may have gracile skeletons due to low physical activity levels and mechanical loading. Tests using pre-historic skeletons are limited by the inability to assess behavior directly, while modern industrialized societies possess few socio-ecological features typical of human evolutionary history. Among Tsimane forager-horticulturalists, we test whether greater activity levels and, thus, increased loading earlier in life are associated with greater later-life bone status and diminished age-related bone loss.

MATERIALS AND METHODS

We used quantitative ultrasonography to assess radial and tibial status among adults aged 20+ years (mean ± SD age = 49 ± 15; 52% female). We conducted systematic behavioral observations to assess earlier-life activity patterns (mean time lag between behavioural observation and ultrasound = 12 years). For a subset of participants, physical activity was again measured later in life, via accelerometry, to determine whether earlier-life time use is associated with later-life activity levels. Anthropometric and demographic data were collected during medical exams.

RESULTS

Structural decline with age is reduced for the tibia (female: -0.25 SDs/decade; male: 0.05 SDs/decade) versus radius (female: -0.56 SDs/decade; male: -0.20 SDs/decade), which is expected if greater loading mitigates bone loss. Time allocation to horticulture, but not hunting, positively predicts later-life radial status (β_Horticulture  = 0.48, p = 0.01), whereas tibial status is not significantly predicted by subsistence or sedentary leisure participation.

DISCUSSION

Patterns of activity- and age-related change in bone status indicate localized osteogenic responses to loading, and are generally consistent with the logic of bone functional adaptation. Nonmechanical factors related to subsistence lifestyle moderate the association between activity patterns and bone structure.

Erythrocyte fatty acid composition of Nepal breast-fed infants

PURPOSE

Essential fatty acids play a critical role in the growth and development of infants, but little is known about the fatty acid status of populations in low-income countries. The objective was to describe the fatty acid composition of red blood cells (RBC) in breastfeed Nepali infants and a subsample of their mothers and to identify the main sources of fatty acids in the mother's diet, as well as the fatty acid composition of breast milk.

METHODS

RBC fatty acid composition was analyzed in a random sample of 303 infants and 72 mother, along with 68 breastmilk samples. Fatty acid profiles of the most important dietary fat sources were analyzed. Information on mother's diet and intake of fat was collected by three 24-h dietary recalls.

RESULTS

In infant RBC's, docosahexaenoic acid (DHA) was the main n-3 fatty acid, and arachidonic acid (AA) was the major n-6 fatty acid. Total n-6 PUFA was three times higher than total n-3 PUFA. Height-for-age (HAZ) was positively associated with DHA status and AA status in multivariable models. The concentration of all fatty acids was higher in children, compared to mothers, except Total n-6 PUFA and Linoleic acid (LA) where no differences were found. The mother's energy intake from fat was 13% and cooking oil (sesame, mustard, soybean or sunflower oil) contributed 52% of the fat intake.

CONCLUSIONS

RBC-DHA levels in both infants and mother was unexpected high taking into account few dietary DHA sources and the low DHA concentrations in breastmilk.

Breast milk DHA levels may increase after informing women: a community-based cohort study from South Dakota USA

BACKGROUND

Docosahexaenoic acid (DHA), an omega-3 fatty acid found in breast milk, has many health benefits for both mother and baby. A 2007 meta-analysis found U.S. women had breast milk DHA levels (0.20% of total fatty acids) below the worldwide mean (0.32%). In 2008, international dietary recommendations were made for pregnant and lactating women to consume 200 mg of DHA per day. This community-based study aimed to define current milk DHA levels from upper Midwest USA lactating mothers and to determine if providing information about their own level along with dietary recommendations would incite changes to increase breast milk DHA content.

METHODS

New mothers attending lactation classes or using hospital pumping rooms in Sioux Falls, South Dakota, USA participated by providing one drop of breast milk on a card for fatty acid analysis at baseline and 1 month after initial reporting. DHA levels were analyzed by gas chromatography. Mothers received a report of their own breast milk level along with dietary recommendations on DHA intake for lactating women. Median baseline and follow-up DHA levels were determined and differences were compared by Wilcoxon signed-rank test.

RESULTS

At baseline, breast milk DHA content (n = 84) was highly variable (range 0.05 to 0.73%) with a median of 0.18% (IQR, 0.13, 0.28; mean ± SD, 0.22 ± 0.13%), well below the worldwide average (0.32%). Women who reported taking DHA supplements (n = 43) had higher levels than those who did not (0.23% vs. 0.15%, P < 0.0001). In a subset of 60 mothers who submitted a second sample, median breast milk DHA content increased from 0.19 to 0.22% (P < 0.01).

CONCLUSIONS

Findings suggest that providing nursing mothers with their breast milk DHA level and education about DHA intake while breastfeeding motivates change to increase DHA levels.

Cognitive performance across the life course of Bolivian forager-farmers with limited schooling

Cognitive performance is characterized by at least two distinct life course trajectories. Many cognitive abilities (e.g., "effortful processing" abilities, including fluid reasoning and processing speed) improve throughout early adolescence and start declining in early adulthood, whereas other abilities (e.g., "crystallized" abilities like vocabulary breadth) improve throughout adult life, remaining robust even at late ages. Although schooling may impact performance and cognitive "reserve," it has been argued that these age patterns of cognitive performance are human universals. Here we examine age patterns of cognitive performance among Tsimane forager-horticulturalists of Bolivia and test whether schooling is related to differences in cognitive performance over the life course to assess models of active versus passive cognitive reserve. We used a battery of eight tasks to assess a range of latent cognitive traits reflecting attention, processing speed, verbal declarative memory, and semantic fluency (n = 919 individuals, 49.9% female). Tsimane cognitive abilities show similar age-related differences as observed in industrialized populations: higher throughout adolescence and only slightly lower in later adulthood for semantic fluency but substantially lower performance beginning in early adulthood for all other abilities. Schooling is associated with greater cognitive abilities at all ages controlling for sex but has no attenuating effect on cognitive performance in late adulthood, consistent with models of passive cognitive reserve. We interpret the minimal attenuation of semantic fluency late in life in light of evolutionary theories of postreproductive life span, which emphasize indirect fitness contributions of older adults through the transfer of information, labor, and food to descendant kin. (PsycINFO Database Record

Growth references for Tsimane forager-horticulturalists of the Bolivian Amazon

OBJECTIVES

Growth standards and references currently used to assess population and individual health are derived primarily from urban populations, including few individuals from indigenous or subsistence groups. Given environmental and genetic differences, growth may vary in these populations. Thus, there is a need to assess whether international standards are appropriate for all populations, and to produce population specific references if growth differs. Here we present and assess growth references for the Tsimane, an indigenous population of Bolivian forager-horticulturalists.

METHODS

Mixed cross-sectional/longitudinal anthropometrics (9,614 individuals; 30,118 observations; ages 0-29 years) were used to generate centile curves and Lambda-Mu-Sigma (LMS) tables for height-for-age, weight-for-age, body mass index (BMI)-for-age, and weight-for-height (WFH) using Generalized Additive Models for Location Shape and Scale (GAMLSS). Velocity curves were generated using SuperImposition by Translation and Rotation (SITAR). Tsimane ≤5 years were compared to World Health Organization (WHO) standards while those >5 years were compared to WHO school age references. All ages were compared to published references for Shuar forager-horticulturalists of the Ecuadorian Amazon.

RESULTS

Tsimane growth differs from WHO values in height and weight, but is similar for BMI and WFH. Tsimane growth is characterized by slow height velocity in childhood and early adolescent peak height velocity at 11.3 and 13.2 years for girls and boys. Tsimane growth patterns are similar to Shuar, suggesting shared features of growth among indigenous South Americans.

CONCLUSIONS

International references for BMI-for-age and WFH are likely appropriate for Tsimane, but differences in height-for-age and weight-for-age suggest Tsimane specific references may be useful for these measures.

Salivary microbiomes of indigenous Tsimane mothers and infants are distinct despite frequent premastication

Background

Premastication, the transfer of pre-chewed food, is a common infant and young child feeding practice among the Tsimane, forager-horticulturalists living in the Bolivian Amazon. Research conducted primarily with Western populations has shown that infants harbor distinct oral microbiota from their mothers. Premastication, which is less common in these populations, may influence the colonization and maturation of infant oral microbiota, including via transmission of oral pathogens. We collected premasticated food and saliva samples from Tsimane mothers and infants (9–24 months of age) to test for evidence of bacterial transmission in premasticated foods and overlap in maternal and infant salivary microbiota. We extracted bacterial DNA from two premasticated food samples and 12 matched salivary samples from maternal-infant pairs. DNA sequencing was performed with MiSeq (Illumina). We evaluated maternal and infant microbial composition in terms of relative abundance of specific taxa, alpha and beta diversity, and dissimilarity distances.

Results

The bacteria in saliva and premasticated food were mapped to 19 phyla and 400 genera and were dominated by Firmicutes, Proteobacteria, Actinobacteria, and Bacteroidetes. The oral microbial communities of Tsimane mothers and infants who frequently share premasticated food were well-separated in a non-metric multi-dimensional scaling ordination (NMDS) plot. Infant microbiotas clustered together, with weighted Unifrac distances significantly differing between mothers and infants. Infant saliva contained more Firmicutes (p < 0.01) and fewer Proteobacteria (p < 0.05) than did maternal saliva. Many genera previously associated with dental and periodontal infections, e.g. Neisseria, Gemella, Rothia, Actinomyces, Fusobacterium, and Leptotrichia, were more abundant in mothers than in infants.

Conclusions

Salivary microbiota of Tsimane infants and young children up to two years of age do not appear closely related to those of their mothers, despite frequent premastication and preliminary evidence that maternal bacteria is transmitted to premasticated foods. Infant physiology and diet may constrain colonization by maternal bacteria, including several oral pathogens.

Health costs of reproduction are minimal despite high fertility, mortality and subsistence lifestyle

Women exhibit greater morbidity than men despite higher life expectancy. An evolutionary life history framework predicts that energy invested in reproduction trades-off against investments in maintenance and survival. Direct costs of reproduction may therefore contribute to higher morbidity, especially for women given their greater direct energetic contributions to reproduction. We explore multiple indicators of somatic condition among Tsimane forager-horticulturalist women (Total Fertility Rate = 9.1; n =  592 aged 15-44 years, n = 277 aged 45+). We test whether cumulative live births and the pace of reproduction are associated with nutritional status and immune function using longitudinal data spanning 10 years. Higher parity and faster reproductive pace are associated with lower nutritional status (indicated by weight, body mass index, body fat) in a cross-section, but longitudinal analyses show improvements in women's nutritional status with age. Biomarkers of immune function and anemia vary little with parity or pace of reproduction. Our findings demonstrate that even under energy-limited and infectious conditions, women are buffered from the potential depleting effects of rapid reproduction and compound offspring dependency characteristic of human life histories.

High resting metabolic rate among Amazonian forager-horticulturalists experiencing high pathogen burden

OBJECTIVES

Resting metabolic rate (RMR) reflects energetic costs of homeostasis and accounts for 60 to 75% of total energy expenditure (TEE). Lean mass and physical activity account for much RMR variability, but the impact of prolonged immune activation from infection on human RMR is unclear in naturalistic settings. We evaluate the effects of infection on mass-corrected RMR among Bolivian forager-horticulturalists, and assess whether RMR declines more slowly with age than in hygienic sedentary populations, as might be expected if older adults experience high pathogen burden.

MATERIALS AND METHODS

RMR was measured by indirect calorimetry (Fitmate MED, Cosmed) in 1,300 adults aged 20 to 90 and TEE was measured using doubly labeled water (n = 40). Immune biomarkers, clinical diagnoses, and anthropometrics were collected by the Tsimane Health and Life History Project.

RESULTS

Tsimane have higher RMR and TEE than people in sedentary industrialized populations. Tsimane RMR is 18 to 47% (women) and 22 to 40% (men) higher than expected using six standard prediction equations. Tsimane mass-corrected TEE is similarly elevated compared to Westerners. Elevated leukocytes and helminths are associated with excess RMR in multivariate regressions, and jointly result in a predicted excess RMR of 10 to 15%. After age 40, RMR declines by 69 kcal/decade (p < .0001). Controlling for lean mass and height accounts for 71% of age-related RMR decline, and adding indicators of infection minimally affects the age slope. The residual level of age-related decline from age 40 is 1.2% per decade.

CONCLUSION

High pathogen burden may lead to higher metabolic costs, which may be offset by smaller body mass or other energy-sparing mechanisms.

Immune function in Amazonian horticulturalists

BACKGROUND

Amazonian populations are exposed to diverse parasites and pathogens, including protozoal, bacterial, fungal and helminthic infections. Yet much knowledge of the immune system is based on industrialised populations where these infections are relatively rare.

AIM

This study examines distributions and age-related differences in 22 measures of immune function for Bolivian forager-horticulturalists and US and European populations.

SUBJECTS AND METHODS

Subjects were 6338 Tsimane aged 0-90 years. Blood samples collected between 2004-2014 were analysed for 5-part blood differentials, C-reactive protein, erythrocyte sedimentation rate (ESR) and total immunoglobulins E, G, A and M. Flow cytometry was used to quantify naïve and non-naïve CD4 and CD8 T cells, natural killer cells, and B cells.

RESULTS

Compared to reference populations, Tsimane have elevated levels of most immunological parameters, particularly immunoglobulins, eosinophils, ESR, B cells, and natural killer cells. However, monocytes and basophils are reduced and naïve CD4 cells depleted in older age groups.

CONCLUSION

Tsimane ecology leads to lymphocyte repertoires and immunoglobulin profiles that differ from those observed in industrialised populations. These differences have consequences for disease susceptibility and co-vary with patterns of other life history traits, such as growth and reproduction.

An updated review of worldwide levels of docosahexaenoic and arachidonic acid in human breast milk by region

OBJECTIVE

We aimed to evaluate the DHA and arachidonic acid (AA) levels in human breast milk worldwide by country, region and socio-economic status.

DESIGN

Descriptive review conducted on English publications reporting breast-milk DHA and AA levels.

SETTING

We systematically searched and identified eligible literature in PubMed from January 1980 to July 2015. Data on breast-milk DHA and AA levels from women who had given birth to term infants were included.

SUBJECTS

Seventy-eight studies from forty-one countries were included with 4163 breast-milk samples of 3746 individuals.

RESULTS

Worldwide mean levels of DHA and AA in breast milk were 0·37 (sd 0·11) % and 0·55 (sd 0·14) % of total fatty acids, respectively. The breast-milk DHA levels from women with accessibility to marine foods were significantly higher than those from women without accessibility (0·35 (sd 0·20) % v. 0·25 (sd 0·14) %, P<0·05). Data from the Asian region showed the highest DHA concentration but much lower AA concentration in breast milk compared with all other regions, independent of accessibility to marine foods. Comparison was made among Canada, Poland and Japan - three typical countries (each with sample size of more than 100 women) from different regions but all with high income and similar accessibility to fish/marine foods.

CONCLUSIONS

The current review provides an update on worldwide variation in breast-milk DHA and AA levels and underlines the need for future population- or region-specific investigations.