Dairy product consumption, dietary nutrient and energy density and associations with obesity in Australian adolescents

Skimmed milk intake reduces the risk of ER- breast cancer: a Mendelian randomization analysis

BACKGROUND

In prior observational investigations, it has been demonstrated that the consumption of milk is associated with the incidence of breast cancer (BC). Despite the existence of a two-sample Mendelian randomization (MR) that suggests a causal relationship between milk intake and breast cancer risk, the outcomes still lack a definitive conclusion. This ambiguity may be attributed to variables such as the variety of milk ingested, estrogen levels, the specific type of BC, and potential confounding factors. Therefore, our principal objective is to establish the causal association between the consumption of skimmed milk and full cream milk and the risk of different types of BC through the utilization of two-sample and two-step MR analyses.

METHODS

In this study, we analyzed single nucleotide polymorphisms associated with skimmed and full-cream milk consumption in a cohort of 360,806 individuals from European populations through genome-wide association studies. We conducted a two-sample MR analysis using three different methods: inverse variance weighting (IVW) was used as the main analysis, and MR-Egger and Weighted median were used as supplementary analyses to IVW. We also performed sensitivity analysis, which included leave-one-out analysis, Cochran's Q test to detect heterogeneity, and MR-Egger intercept analysis to detect potential biases caused by pleiotropy. We used two-step MR analysis to evaluate potential mediators of associations.

RESULTS

In the two-sample MR analysis, IVW analysis suggests a potential inverse causal relationship between skimmed milk and BC [OR 0.34, 95% CI (0.12-1.00), P = 0.05]. Subgroup analysis revealed that skimmed milk reduces the risk of estrogen receptor-negative (ER-) breast cancer [OR 0.18, 95% CI (0.04-0.90), P = 0.04], but not estrogen receptor-positive (ER+) breast cancer [OR 0.42, 95% CI (0.15-1.22), P = 0.11]. MR Egger reached similar results, that is, skimmed milk reduces the risk of ER- breast cancer [OR 0.006, 95% CI (0.00-0.70), P = 0.04], but not BC [OR 0.16, 95% CI (0.01-4.66), P = 0.30] and ER+ breast cancer [OR 0.50, 95% CI (0.02-12.61), P = 0.65]. Additionally, we found no causal relationship between full cream milk and BC (P > 0.05). In two-step MR analysis, we found evidence for a mediating role of BMI in the relationship between skimmed milk intake and ER-breast cancer risk.

CONCLUSION

Our findings strengthen the evidence for a protective effect of skimmed milk consumption on ER-breast cancer risk. Further two-step MR analyses suggest that this protective effect may partly result from body mass index (BMI). There is no evidence that full cream milk consumption affects the risk of BC.

What Determinants Are Related to Milk and Dairy Product Consumption Frequency among Children Aged 10-12 Years in Poland? Nationwide Cross-Sectional Study

Due to their high nutritional value, milk and dairy products should be a permanent element of a properly balanced diet for children and adolescents. The study aimed to identify (i) the frequency of milk and dairy product consumption by children aged 10-12 years in the opinion of children and their parents and (ii) the determinants related to the consumption of these products (including lifestyle, nutrition knowledge, and the nutritional status of children's as well as parents' nutrition knowledge). A cross-sectional study was conducted with 12,643 primary school students aged 10-12 and 7363 parents. Dietary data were collected using the Food Frequency Consumption and Nutritional Knowledge Questionnaire (SF-FFQ4PolishChildren® and KomPAN®). Anthropometric measurements were taken and body mass index (BMI) and waist/height ratios (WHtR) were calculated. A logistic regression model was used to assess the likelihood of the frequent consumption of dairy products in the opinion of both the children and their parents, and the quality of the obtained models was assessed using model fit statistics and the Hosmer and Lemeshow test. The frequency of consuming milk and milk products (every day and more) was low in the opinion of children aged 10-12 years (29.6%). According to their parents, the frequency of the consumption of dairy products was slightly higher (44.8%). Six factors associated with the frequency of milk and dairy product consumption were identified independently. These included schoolchildren and their parents' nutrition knowledge, physical activity, sleep, gender, and place of residence. More of these products were consumed by children with greater nutrition knowledge-both their own and their parents'-higher physical activity, longer sleep duration, males, and those living in the city. Family eating habits, particularly eating meals together, also played an important role in the consumption of milk and dairy products. According to the parents, the children in older grades were less likely to consume dairy products more frequently. The obtained results suggest an insufficient consumption of milk and dairy products. The identification of modifiable factors, such as nutrition knowledge, physical activity, sleep duration, and eating meals with the family, suggests the need to improve the existing strategies, including activities encouraging nutritional education for both schoolchildren and their parents.

Total dairy consumption in relation to overweight and obesity in children and adolescents: A systematic review and meta-analysis

A systematic review and meta-analysis of cross-sectional and prospective cohort studies was conducted to assess the associations between total dairy consumption and its different subtypes with the prevalence and incidence of overweight, obesity, and overweight/obesity in children and adolescents. A literature search was conducted in Medline through PUBMED and Cochrane Library databases until October 18, 2021. Articles reporting the risk estimates as odd ratios (OR), risk ratios (RR), or hazard ratios and their corresponding 95% confidence interval (CI) for the association between dairy product consumption and the risk of overweight and/or obesity were included. In the meta-analysis from cross-sectional studies, results showed an inverse association between total dairy consumption and obesity prevalence (OR (95% CI): 0.66 (0.48-0.91). No significant associations were found between milk or yogurt and obesity prevalence risk. Regarding prospective studies, total milk consumption was positively associated with overweight prevalence (OR (95% CI): 1.13 (1.01-1.26)) and incidence (RR (95%CI): 1.17 (1.01-1.35)) risk. Evidence from pooled analysis of cross-sectional studies suggested an inverse association between total dairy consumption and obesity. However, there is limited and no conclusive evidence to confirm an inverse relationship from pooled analysis of prospective studies in children and adolescents.

The relationship between dairy products intake and breast cancer incidence: a meta-analysis of observational studies

BACKGROUND

The effect of dairy products intake on breast cancer (BC) is highly controversial. This study aims to investigate the relationship between dairy intake and BC incidence.

METHODS

A search was carried out in PubMed, EBSCO, Web of Science, and Cochrane Library databases before January 2021. The primary objective was the risk of BC and intake of dairy products were exposure variables.

RESULTS

The meta-analysis comprised 36 articles with 1,019,232 participants. Total dairy products have a protective effect on female population (hazard ratio (HR) =0.95, 95% confidence interval (CI) =0.91-0.99, p = 0.019), especially for estrogen receptor-positive (ER+) (HR = 0.79, p = 0.002) and progesterone receptor-positive (PR+) BC (HR = 0.75, p = 0.027). For ER+/PR+ BC, there is a trend of protection, but it has not reached statistical significance (HR = 0.92, p = 0.075). Fermented dairy products can reduce BC risk in postmenopausal population (HR = 0.96, 95%CI = 0.93-0.99, p = 0.021), but have no protective effect on premenopausal population (HR = 0.98, 95%CI = 0.94-1.03, p = 0.52). Non-fermented dairy products have no significant effect on BC occurrence (p > 0.05). High-fat dairy products are harmful to women, without statistical difference (HR = 1.06, 95%CI = 1.00-1.13, p = 0.066). On the contrary, low-fat dairy products can protect the premenopausal population (HR = 0.94, 95%CI = 0.89-1.00, p = 0.048).

CONCLUSION

The intake of dairy products can overall reduce BC risk in the female population, but different dairy products have varying effects on different BC subtypes and menopausal status.

The association of dietary energy density and the risk of obesity, type 2 diabetes and metabolic syndrome: A systematic review and meta-analysis of observational studies

OBJECTIVES

There is a growing body of evidence linking dietary energy density (DED) with metabolic disorders like obesity, type 2 diabetes (T2D) and metabolic syndrome (MetS). However, according to our knowledge, there has been no systematic review and mate-analysis on T2D and MetS with DED. Therefore, this study aimed to investigate the association between DED with the risk of obesity, T2D and MetS in a systematic review and meta-analysis of observational studies.

METHODS

We searched all published studies according to the defined keywords up to march 2020 in the PubMed/Medline and Scopus databases. We excluded those that did not calculate DED for total intake, no observed association between obesity, T2D, MetS as the primary or one of the outcomes with DED, no reported odds ratio (OR), relative risk (RR) or hazard ratio (HR) estimates with 95% confidence intervals (CIs), studies in children under 2 years old, patients with cancer and pregnant women.

RESULTS

From 2282, after deleting the duplicates and irrelevant studies, we entered 58 articles ( 47 systematic reviews and 11 meta-analyse). We indicated an increased risk of T2D in relation to DED (OR: 1.25, 95% CI: 1.18-1.33, P < .001). But studies reviewed were inconsistent. All studies which examined the relationship between DED and MetS showed a positive relationship with an increased significant risk (OR: 1.59, 95% CI: 1.22-2.07, P < .001). Most articles reported a direct association between DED and obesity but the relationship between DED and risk of obesity was not significant (OR: 1.04, 95% CI: 0.92-1.17, P = .543).

CONCLUSION

In this systematic review and meta-analysis of observational studies, we found that the DED increased the risk of T2D and MetS but was not significant with the risk of obesity.

Dose-Response Relationship between Western Diet and Being Overweight among Teachers in Malaysia

The rising prevalence of overweight and obesity is partly due to nutrition transition. The reported association between dietary patterns and overweight/obesity has been controversial because of inconsistent results and weak observed associations. Although it has been hypothesized that an unhealthy diet can increase obesity risk, none of the previous studies have examined the dose-response association using nonlinear dose-response analyses. This study aimed to examine the dose-response association between major dietary patterns and overweight/obesity. This was a cross-sectional study involving teachers selected through stratified multistage sampling from public schools in three Malaysian states. Dietary intake was assessed using a food frequency questionnaire, and two major dietary patterns (Western and Prudent diet) were extracted using factor analysis. Logistic regression followed by trend analysis was used to test the difference in odds of overweight and obesity in each quintile of diet score. A further analysis using restricted cubic spline models was performed to examine the dose-response associations of dietary patterns with odds of overweight/obesity. The logistic regression analysis showed that participants with the highest quintile of Western diet score were 1.4 times more likely to be overweight/obese compared to those in the lowest quintile (95% CI: 1.11, 1.83, p-trend < 0.001). The odds of overweight/obesity showed a significant increasing trend across quintiles of Western diet among both men and women (p-trend < 0.001). In the dose-response analysis, a positive linear association (P_nonlinearity = 0.6139) was observed where overweight/obesity was more likely to occur among participants with a Western diet score greater than a mean score of zero. There was an inverse trend of odds of overweight/obesity across quintiles of Prudent diet score, significant only for men (p for trend < 0.001). Linear association was found between Prudent diet score and odds of overweight/obesity among both men (P_nonlinearity = 0.6685) and women (P_nonlinearity = 0.3684) in the dose-response analysis. No threshold at the level of adherence to Prudent diet was linked to odds of overweight/obesity. Dose-response analysis indicated that women with a Western diet score greater than zero were more likely to be overweight or obese among women. In men, higher adherence to Western diet was associated with increased odds of overweight/obesity, while greater adherence to Prudent diet decreased the odds of overweight/obesity. Promoting and enhancing the consumption of Prudent diet and limit in Western diet may be used to guide the development of evidence-based diet interventions to curb overweight and obesity.

Toward Healthy Diets from Sustainable Food Systems

This article is based on a session at ASN 2019 entitled "Addressing the Four Domains of Sustainable Food Systems Science (Health, Economics, Society and the Environment): What Will It Take to Harmonize the Evidence to Advance the Field?" A summary of presentations is included. The presentations addressed the 4 principal domains of sustainability defined as nutrition/health, economics, environment, and society and the ways in which they are represented in current research. The session also introduced metrics and measures that are specific to each domain. Participants discussed next steps to move toward consensus and collaboration among scientific communities, especially those of health/nutrition science and environmental science. Food systems may need to be restructured to ensure that the global food supply provides adequate calories and nutrients at an affordable cost. Finally, the session addressed strategies to implement research concepts and move toward policies that encourage consumers to choose healthy diets from sustainable food systems.

Measures and metrics of sustainable diets with a focus on milk, yogurt, and dairy products

The 4 domains of sustainable diets are nutrition, economics, society, and the environment. To be sustainable, foods and food patterns need to be nutrient-rich, affordable, culturally acceptable, and sparing of natural resources and the environment. Each sustainability domain has its own measures and metrics. Nutrient density of foods has been assessed through nutrient profiling models, such as the Nutrient-Rich Foods family of scores. The Food Affordability Index, applied to different food groups, has measured both calories and nutrients per penny (kcal/$). Cultural acceptance measures have been based on relative food consumption frequencies across population groups. Environmental impact of individual foods and composite food patterns has been measured in terms of land, water, and energy use. Greenhouse gas emissions assess the carbon footprint of agricultural food production, processing, and retail. Based on multiple sustainability metrics, milk, yogurt, and other dairy products can be described as nutrient-rich, affordable, acceptable, and appealing. The environmental impact of dairy farming needs to be weighed against the high nutrient density of milk, yogurt, and cheese as compared with some plant-based alternatives.

Dietary energy density is associated with body mass index-for-age in Mexican adolescents

Dietary energy density (DED) has been widely considered a risk factor for weight gain. In adolescents, however, the evidence is inconclusive, and in Mexico, the ways in which DED is associated with overweight and obesity are unknown. Our study analysed the association of DED with overweight or obesity (OW-O) in Mexican adolescents included in the National Health and Nutrition Survey 2012 (ENSANUT 2012). We analysed the data from a 7-day Food Frequency Questionnaire administered to 2,203 Mexican adolescents aged 12-19 years. DED was calculated excluding all beverages. Plausible and implausible reporters were identified based on the relationship between the reported energy intake and the estimated energy requirement. The association of DED with body mass index (BMI)-for-age and OW-O was analysed using multivariate statistical models restricted to plausible reporters. The combined prevalence of overweight and obesity was 35.4% in the complete sample and 27.8% in the sample of plausible reporters. Mean DED was 177 kcal/100 g, with higher DED in the north of the country. The proportion of plausible reporters was 38.5%. We found a positive association between high DED and the BMI-for-age z-score (β = 0.347; 95% CI [0.101, 0.594]; P = 0.006), controlling for sociodemographic and dietary variables, but no significant association with OW-O. It is necessary to consider the DED in the design and implementation of strategies to reduce energy density in the diets of young Mexicans.

Child and Adolescent Sugar-Sweetened Beverage Intakes Are Longitudinally Associated with Higher Body Mass Index z Scores in a Birth Cohort Followed 17 Years

BACKGROUND

Sugar-sweetened beverages (SSB) are considered a risk factor for obesity.

OBJECTIVE

The objective of the current study was to investigate associations between the predictors of beverage and energy intakes and mean adequacy ratios (MARs), and the outcome of body mass index (BMI) z scores, in a birth cohort using longitudinal models.

DESIGN

This was a longitudinal analysis of secondary data.

PARTICIPANTS/SETTING

Participants in the Iowa Fluoride and Iowa Bone Development Studies with two beverage intake questionnaires completed between ages 2 and 4.7 years or 5 and 8.5 years or one questionnaire between ages 9 and 10.5, 11 and 12.5, 13 and 14.5, or 15 and 17 years (n=720); two food and beverage diaries completed between ages 2 and 4.7 years or 5 and 8.5 years or completion of the Block's Kids' Food Frequency Questionnaires at age 11, 13, 15, or 17 years (n=623); and anthropometric measures at the corresponding age 5-, 9-, 11-, 13-, 15-, or 17-year examination(s).

PREDICTORS

Mean daily 100% juice, milk, SSB, water/sugar-free beverage, and energy intakes and MARs averaged over ages 2 to 4.7, 5 to 8.5, 9 to 10.5, 11 to 12.5, 13 to 14.5, or 15 to 17 years were predictors.

OUTCOME

BMI z score was the outcome.

STATISTICAL ANALYSES

Linear mixed models were fit for each beverage, energy, and MAR variable, with the beverage, energy, or MAR variable as the predictor and BMI z score as the outcome. Beverage models were adjusted for energy and MAR and baseline socioeconomic status.

RESULTS

SSB intake adjusted for energy intake, MAR, and baseline socioeconomic status was associated with BMI z score; each additional 8 oz SSB consumed/day throughout childhood and adolescence increased the BMI z score an average 0.050 units (95% CI 0.022 to 0.079; P=0.001). Adjusted water/sugar-free beverage intake (0.026 units; 95% CI 0.006 to 0.046; P=0.013) was modestly associated with BMI z score, while 100% juice (-0.001 units; 95% CI -0.059 to 0.057; P=0.97) and milk (0.022 units; 95% CI -0.007 to 0.052; P=0.13) intakes were not associated with BMI z scores.

CONCLUSIONS

Higher SSB intakes were associated with increased BMI z scores throughout childhood and adolescence in Iowa Fluoride Study participants. Public health initiatives targeting SSB consumption during childhood and adolescence remain relevant.

Associations of dietary energy density with body composition and cardiometabolic risk in children with overweight and obesity: role of energy density calculations, under-reporting energy intake and physical activity

This study examined (1) the association of dietary energy density from solid (EDS) and solid plus liquids (EDSL) with adiposity and cardiometabolic risk factors (CRF) in children with overweight and obesity, (2) the effect of under-reporting on the mentioned associations and (3) whether the association between ED and body composition and CRF is influenced by levels of physical activity. In a cross-sectional design, 208 overweight and obese children (8–12-year-old; 111 boys) completed two non-consecutive 24 h recalls. ED was calculated using two different approaches: EDS and EDSL. Under-reporters were determined with the Goldberg method. Body composition, anthropometry and fasting blood sample measurements were performed. Moderate to vigorous physical activity (MVPA) was registered with accelerometers (7-d-register). Linear regressions were performed to evaluate the association of ED with the previously mentioned variables. Neither EDS nor EDSL were associated with body composition or CRF. However, when under-reporters were excluded, EDS was positively associated with BMI (P=0·019), body fat percentage (P=0·005), abdominal fat (P=0·008) and fat mass index (P=0·018), while EDSL was positively associated with body fat percentage (P=0·008) and fat mass index (P=0·026). When stratifying the group according to physical activity recommendations, the aforementioned associations were only maintained for non-compliers. Cluster analysis showed that the low-ED and high-MVPA group presented the healthiest profile for all adiposity and CRF. These findings could partly explain inconsistencies in literature, as we found that different ED calculations entail distinct results. Physical activity levels and excluding under-reporters greatly influence the associations between ED and adiposity in children with overweight and obesity.

Dietary Energy Density and Its Association with Overweight or Obesity in Adolescents: A Systematic Review of Observational Studies

Dietary energy density (DED) has been identified as a crucial dietary factor in body weight control, in that higher DED has been associated with weight gain. To our knowledge, no review studies have explained this association specifically in adolescents. The aim of this study was to describe the association of DED with overweight or obesity (OW/O) in adolescents, as derived from observational studies. We conducted a systematic search of the MEDLINE/PubMed and Science Direct databases, including studies published between January 2000 and December 2017. We selected the studies that included adolescents (aged 10⁻19 years) and contained DED-related information and anthropometric measurements of OW/O. From 1149 candidate studies, 30 were selected, though only 12 met all the inclusion criteria. Of these, only four found a positive association between DED and certain OW/O indicators, six found no association and two showed an inverse association with weight gain. These studies differed in several aspects such as design, DED calculation method and dietary assessment tool, leading to inconsistent results. Methodological differences found among the examined studies did not allow us to establish a clear conclusion of this association. Evidence in adolescents was also poor. New, standardized methodological approaches should be considered in future studies.

Uses of nutrient profiling to address public health needs: from regulation to reformulation

Nutrient profiling (NP) models rate the nutritional quality of individual foods, based on their nutrient composition. Their goal is to identify nutrient-rich foods, generally defined as those that contain more nutrients than calories and are low in fat, sugar and salt. NP models have provided the scientific basis for evaluating nutrition and health claims and regulating marketing and advertising to children. The food industry has used NP methods to reformulate product portfolios. To help define what we mean by healthy foods, NP models need to be based on published nutrition standards, mandated serving sizes and open-source nutrient composition databases. Specifically, the development and testing of NP models for public health should follow the seven decision steps outlined by the European Food Safety Authority. Consistent with this scheme, the nutrient-rich food (NRF) family of indices was based on a variable number of qualifying nutrients (from six to fifteen) and on three disqualifying nutrients (saturated fat, added sugar, sodium). The selection of nutrients and daily reference amounts followed nutrient standards for the USA. The base of calculation was 418·4 kJ (100 kcal), in preference to 100 g, or serving sizes. The NRF algorithms, based on unweighted sums of percent daily values, subtracted negative (LIM) from positive (NRn) subscores (NRn - LIM). NRF model performance was tested with respect to energy density and independent measures of a healthy diet. Whereas past uses of NP modelling have been regulatory or educational, voluntary product reformulation by the food industry may have most impact on public health.

Dairy products intake and cancer mortality risk: a meta-analysis of 11 population-based cohort studies

BACKGROUND

Dairy products are major components of daily diet and the association between consumption of dairy products and public health issues has captured great attention. In this study, we conducted a meta-analysis to investigate the association between dairy products intake and cancer mortality risk.

METHODS

After a literature search in PubMed and EMBASE, 11 population-based cohort studies involving 778,929 individuals were considered eligible and included in the analyses. Data were extracted and the association between dairy products intake and cancer mortality risk was estimated by calculating pooled relative risks (RRs) and corresponding 95 % confidence intervals (CIs). Sensitivity analyses and subgroup analyses based on regions, genders and dairy types were performed as well. Potential dose-response relationship was further explored by adopting the generalized least squares (GLST) method.

RESULTS

Total dairy products intake was not associated with all cancer mortality risk, with the pooled RR of 0.99 (95 % CI 0.92-1.07, p = 0.893). Subgroup analyses showed that the pooled RRs were 0.97 (95 % CI 0.92-1.03, p = 0.314) for milk, 0.88 (95 % CI 0.71-1.10, p = 0.271) for yogurt, 1.23 (95 % CI 0.94-1.61, p = 0.127) for cheese and 1.13 (95 % CI 0.89-1.44, p = 0.317) for butter in male and female, however the pooled RR was 1.50 (95 % CI 1.03-2.17, p = 0.032) for whole milk in male, which was limited to prostate cancer. Further dose-response analyses were performed and we found that increase of whole milk (serving/day) induced elevated prostate cancer mortality risk significantly, with the RR of 1.43 (95 % CI 1.13-1.81, p = 0.003).

CONCLUSIONS

Total dairy products intake have no significant impact on increased all cancer mortality risk, while low total dairy intake even reduced relative risk based on the non-linear model. However, whole milk intake in men contributed to elevated prostate cancer mortality risk significantly. Furthermore, a linear dose-response relationship existed between increase of whole milk intake and increase of prostate cancer mortality risk.

Associations between dietary energy density and obesity: A systematic review and meta-analysis of observational studies

OBJECTIVE

Although many studies have shown an association between dietary energy density (DED) and obesity, there has been no systematic review and meta-analysis on this topic. Therefore, the objective of this study was to qualitatively and quantitatively review and summarize the literature on association between DED and obesity.

METHODS

We searched titles, abstracts, and keywords of articles indexed in ScienceDirect, ProQuest, MEDLINE, and Google Scholar databases until January 2015 to identify eligible studies. We excluded studies that did not examine DED for whole diet and studies that included patients with cancer, pregnant women, the elderly (>60 y old), and children (<2 y old). There were no language or publication date restrictions.

RESULTS

Of the 37 studies included in this review, most articles reported a direct association between DED and obesity. We performed a meta-analysis on 23 of these studies. In comparison with the lowest NTILE of DED, subjects in the highest NTILE of DED had significant weight gain (2.26 kg, 95% confidence interval [CI]: 1.00-3.53), greater adjusted mean body mass index (BMI) (0.50 kg/m(2), 95% CI: 0.02-0.98 for males and 0.85 kg/m(2), 95% CI: 0.51-1.19 for females), and risk of excess adiposity (odds ratio [OR]: 1.27, 95% CI: 1.04-1.55). We did not observe significant associations between DED and risk of elevated BMI (OR: 1.13, 95% CI: 1.00-1.27) and abdominal obesity (OR: 1.17, 95% CI: 0.19-7.38). We found no evidence of publication bias.

CONCLUSION

The present review showed that DED was directly associated with risk of excess adiposity, higher weight change, and BMI. Lower DED should be considered a prevention strategy for obesity.

Dairy Intake Enhances Body Weight and Composition Changes during Energy Restriction in 18-50-Year-Old Adults-A Meta-Analysis of Randomized Controlled Trials

Background/Aims: A meta-analysis of randomized controlled trials (RCTs) was performed to investigate the effects of dairy food or supplements during energy restriction on body weight and composition in 18–50-year-old. Methods: RCTs ≥ 4 weeks comparing the effect of dairy consumption (whole food or supplements) with control diets lower in dairy during energy restriction on body weight, fat and lean mass were identified by searching MEDLINE, EMBASE, Pubmed, Cochrane Central and World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) until March 2016. Reports were identified and critically appraised in duplicate. Data were pooled using random-effects meta-analysis. Chi²- and I²-statistics indicated heterogeneity. Dose effect was assessed using meta-regression analysis. GRADE guidelines were used to rate the quality (QR) of the evidence considering risk of bias, inconsistency, indirectness, imprecision, publication bias and effect estimates. Results: 27 RCTs were reviewed. Participants consumed between 2 and 4 standard servings/day of dairy food or 20–84 g/day of whey protein compared to low dairy control diets, over a median of 16 weeks. A greater reduction in body weight (−1.16 kg [−1.66, −0.66 kg], p < 0.001, I² = 11%, QR = high, n = 644) and body fat mass (−1.49 kg [−2.06, −0.92 kg], p < 0.001, I² = 21%, n = 521, QR = high) were found in studies largely including women (90% women). These effects were absent in studies that imposed resistance training (QR = low-moderate). Dairy intake resulted in smaller loss of lean mass (all trials pooled: 0.36 kg [0.01, 0.71 kg], p = 0.04, I² = 64%, n = 651, QR = moderate). No between study dose-response effects were seen. Conclusions: Increased dairy intake as part of energy restricted diets resulted in greater loss in bodyweight and fat mass while attenuating lean mass loss in 18–50-year-old adults. Further research in males is needed to investigate sex effects.

Adaptation to Lactose in Lactase Non Persistent People: Effects on Intolerance and the Relationship between Dairy Food Consumption and Evalution of Diseases

Dairy foods contain complex nutrients which interact with the host. Yet, evolution of lactase persistence has divided the human species into those that can or cannot digest lactose in adulthood. Such a ubiquitous trait has differential effects on humanity. The literature is reviewed to explore how the divide affects lactose handling by lactase non persistent persons. There are two basic differences in digesters. Firstly, maldigesters consume less dairy foods, and secondly, excess lactose is digested by colonic microflora. Lactose intolerance in maldigesters may occur with random lactose ingestion. However, lactose intolerance without maldigestion tends to detract from gaining a clear understanding of the mechanisms of symptoms formation and leads to confusion with regards to dairy food consumption. The main consequence of intolerance is withholding dairy foods. However, regular dairy food consumption by lactase non persistent people could lead to colonic adaptation by the microbiome. This process may mimic a prebiotic effect and allows lactase non persistent people to consume more dairy foods enhancing a favorable microbiome. This process then could lead to alterations in outcome of diseases in response to dairy foods in lactose maldigesters. The evidence that lactose is a selective human prebiotic is reviewed and current links between dairy foods and some diseases are discussed within this context. Colonic adaptation has not been adequately studied, especially with modern microbiological techniques.