Maternal Nutrition, Genetics, and Human Milk Lipids

Human Milk Lipids and Small Metabolites: Maternal and Microbial Origins

Although there has been limited application in the field to date, human milk omics research continues to gain traction. Human milk lipidomics and metabolomics research is particularly important, given the significance of milk lipids and metabolites for infant health. For researchers conducting compositional milk analyses, it is important to consider the origins of these compounds. The current review aims to provide a summary of the existing evidence on the sources of human milk lipids and small metabolites. Here, we describe five major sources of milk lipids and metabolites: de novo synthesis from mammary cells, production by the milk microbiota, dietary consumption, release from non-mammary tissue, and production by the gut microbiota. We synthesize the literature to provide evidence and understanding of these pathways in the context of mammary gland biology. We recommend future research focus areas to elucidate milk lipid and small metabolite synthesis and transport pathways. Better understanding of the origins of human milk lipids and metabolites is important to improve translation of milk omics research, particularly regarding the modulation of these important milk components to improve infant health outcomes.

Assessment of Fatty Acid Content in the Milk of Women from the West Pomeranian Region of Poland with Regard to Supplementation and the Amount of Adipose Tissue

The total amount of fat in the milk of nursing mothers depends on maternal reserves, as well as food intake and its synthesis in the mammary glands. The aim of this study was to assess the contents of fatty acids in the milk of women from the West Pomeranian region of Poland with regards to supplementation and the amount of adipose tissue. We also wanted to find out whether these women, who have direct access to the sea and potential access to fresh marine fish, have higher levels of DHA.

METHODS

We analyzed milk samples obtained 6-7 weeks postpartum from 60 women. The content of fatty acid methyl esters (FAME) in lipids was determined by gas chromatography-mass spectrometry (GC/MS) using a Clarus 600 device (PerkinElmer).

RESULTS

Women using dietary supplements had significantly higher levels of docosahexaenoic acid (DHA) (C22:6 n-3) (p = 0.000) and eicosapentaenoic acid (EPA) (20:5 n-3) (p = 0.000). The levels of eicosatrienoic acid (ETA) (C20:3 n-3) and γ-linolenic acid (GLA) increased with the amount of body fat, and the level of DHA was lowest in subjects where body fat exceeded 40% (p = 0.036).

CONCLUSIONS

The contents of fatty acids in the milk of women from the West Pomeranian region of Poland were similar to that reported by other authors. The levels of DHA in women using dietary supplements was also comparable to the values reported worldwide. BMI had an effect on the levels of ETE and GLA acids.

The road not taken: host genetics in shaping intergenerational microbiomes

The early-life gut microbiome is linked to human phenotypes as an imbalanced microbiome of this period is implicated in diseases throughout life. Several determinants of early-life gut microbiome are explored, however, mechanisms of acquisition, colonization, and stability of early-life gut microbiome and their interindividual variability remain elusive. Host genetics play a vital role to shape the gut microbiome and interact with it to modulate individual phenotypes in human studies and animal models. Given the microbial linkage between host generations, we discuss the current state of roles of host genetics in forming intergenerational microbiomes associated with mothers, offspring, and those vertically transmitted, providing a basis for taking into account host genetics in future early-life microbiome research. We further expand our discussion to the bidirectional interactions between host gene expression and microbiome in human health.

Effects of Maternal Exclusion Diet for Infants Suspected Food Allergy on Fatty Acid Composition in Breast Milk

Background: Levels of fatty acid (FA) in breast milk (BM) may vary depending on the maternal diet. This study aimed to explore FA composition in BM of lactating women following dietary restrictions due to infant allergic conditions. Materials and Methods: Thai lactating mothers of term infants who were on exclusion diets were recruited. Mature BM was collected before and after a period (at least 2 weeks) of dietary restriction. FA in BM was analyzed by gas chromatography-mass spectrometry. Results: Fifty lactating women 33.7 ± 3.6 years of age were enrolled. Thirty-three percent of the lactating mothers restricted more than eight food items. Most common dietary restriction were cow's milk (88%) and eggs (74%). After the period of dietary exclusion, total polyunsaturated FA showed no significant change, while saturated FA (SFA) declined, and monounsaturated FA (MUFA) increased. A decrease in fat intake was associated with an increase in arachidonic acid (ARA) and docosahexaenoic acid (DHA) content in BM (r = -0.37, r = -0.36; p < 0.05). However, a rise in ARA, eicosapentaenoic acid (EPA), and DHA intake was associated with an increase in linoleic acid and EPA in BM, respectively (r = 0.38, r = 0.55 and r = 0.41; p < 0.05). Infant weight-for-age z-score did not significantly change after the period of maternal dietary exclusion. Conclusion: Maternal exclusion diet resulted in lower SFA and higher MUFA composition in BM. Further study should explore the long-term outcomes of maternal dietary restriction on infant and child health.

Functional Significance of Different Milk Constituents in Modulating the Gut Microbiome and Infant Health

Human milk, the gold standard for optimal nourishment, controls the microbial composition of infants by either enhancing or limiting bacterial growth. The milk fat globule membrane has gained interest in gut-related functions and cognitive development. The membrane proteins can directly interact with probiotic bacteria, influencing their survival and adhesion through gastrointestinal transit, whereas membrane phospholipids increase the residence time of probiotic bacteria in the gut. The commensal bacteria in milk act as the initial inoculum in building up the gut colonization of an infant, whereas oligosaccharides promote proliferation of beneficial microorganisms. Interestingly, milk extracellular vesicles are also involved in influencing the microbiota composition but are not well-explored. This review highlights the contribution of different milk components in modulating the infant gut microbiota, particularly the fat globule membrane, and the complex interplay between host- and brain-gut microbiota signaling affecting infant and adult health positively.

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.

Comprehensive analysis of fatty acids in human milk of four Asian countries

Human milk lipids provide not only energy but also indispensable bioactive components such as essential fatty acids. To establish the recommended daily intake value and guidelines for infant formula, a reference library of fatty acid composition has been generated from 4 Asian countries (South Korea, China, Vietnam, and Pakistan). Regardless of country, palmitic acid (C16:0), linoleic acid (C18:1), and linolenic acid (C18:2) were the 3 most abundant fatty acids in human milk and account for more than 75% of total fatty acids (total FA). However, there were several considerable differences between fatty acids, particularly n-3 and n-6 (omega-3 and omega-6) groups. Chinese mothers' milk had a high concentration of linoleic acid at 24.38 ± 10.02% of total FA, which may be due to maternal diet. Among the 4 countries, Pakistani mothers' milk contained a high amount of saturated fatty acid (56.83 ± 5.96% of total FA), and consequently, polyunsaturated fatty acids, including n-3 and n-6, were significantly lower than in other countries. It is noteworthy that docosahexaenoic acid (DHA) in Pakistani mothers' milk was 44.8 ± 33.3 mg/L, which is only 25 to 30% of the levels in the other 3 countries, suggesting the need for DHA supplementation for infants in Pakistan. Moreover, the ratio of n-6 to n-3 was also remarkably high in Pakistani mothers' milk (15.21 ± 4.96), being 1.4- to 1.7-fold higher than in other countries. The average DHA:ARA ratio in Asian human milk was 1.01 ± 0.79. Korean mothers' milk showed a high DHA:ARA ratio, with a value of 1.30 ± 0.98, but Pakistani mothers' milk had a significantly lower value (0.42 ± 0.12). The fatty acid compositions and anthropometric data of mother (body mass index, age) did not show any correlation. The obtained data might provide information about human milk compositions in the Asian region that could benefit from setting up recommended nutrient intake and infant formula for Asian babies.

The Gut‒Breast Axis: Programming Health for Life

The gut is a pivotal organ in health and disease. The events that take place in the gut during early life contribute to the programming, shaping and tuning of distant organs, having lifelong consequences. In this context, the maternal gut plays a quintessence in programming the mammary gland to face the nutritional, microbiological, immunological, and neuroendocrine requirements of the growing infant. Subsequently, human colostrum and milk provides the infant with an impressive array of nutrients and bioactive components, including microbes, immune cells, and stem cells. Therefore, the axis linking the maternal gut, the breast, and the infant gut seems crucial for a correct infant growth and development. The aim of this article is not to perform a systematic review of the human milk components but to provide an insight of their extremely complex interactions, which render human milk a unique functional food and explain why this biological fluid still truly remains as a scientific enigma.

[Effect of omega-3 supplementation during pregnancy and lactation on the fatty acid composition of breast milk in the first months of life: a narrative review]

Introduction

Omega-3 long-chain, polyunsaturated fatty acids are essential, so they must be provided through the diet, as their biological synthesis is limited, making it essential to meet their requirements during physiological stages such as pregnancy and lactation. A narrative review was conducted on the effects of omega-3 supplementation during pregnancy and lactation on the fatty acid composition of breast milk in the first months of life. Eight randomized clinical studies were analyzed, showing a significant increase in docosahexaenoic acid (DHA) concentration in breast milk (BM) post-supplementation, compared to control groups. One study evaluated the dose needed to achieve 8 % DHA in erythrocytes and 1 % DHA in BM, reaching these levels with a supplementation close to 1 g of docosahexaenoic acid + eicosapentaenoic acid (EPA). Finally, a trial was found that used supplementation with small lipid contributions (0,59 g α-linolenic acid (ALA)), without generating significant changes in the DHA composition of LM, but in the ALA content. Therefore, it is inferred that omega-3 supplementation beneficially modifies DHA and EPA levels in the composition of BM in pregnant women and during the lactation stage, although further studies are needed to identify doses, times, beneficial effects on development, and more efficient forms of delivery of omega-3 supplementation.

Changes in human milk fatty acid composition and maternal lifestyle-related factors over a decade: a comparison between the two Ulm Birth Cohort Studies

Human milk fatty acid composition varies during lactation and is influenced by maternal diet, maternal lifestyle-related factors and genetic background. This is one of the first studies to investigate a period effect, that is, the impact of lifestyle-related changes on human milk fatty acid composition, in two different cohorts. Lactating women were recruited from the general population a decade apart in Ulm, Germany, using similar methodology. Human milk samples collected 6 weeks postpartum were analysed (Ulm Birth Cohort Study (UBCS (2000)), n 567; Ulm SPATZ Health Study (SPATZ (2012)), n 458). Centred log ratio transformation was applied to fatty acid data. Principal component analysis was used to determine study-dependent fatty acid profiles. A general linear model was used to determine the study (or period) effect on fatty acid profiles adjusting for duration of gestation, age, education, delivery mode, smoking and pre-pregnancy BMI. Two principal components were retained (PC1 and PC2). PC1 was associated with UBCS, while PC2 was associated with SPATZ. PC1 comprised high SFA, and low MUFA, n-6 and n-3 long-chain PUFA (LCPUFA). The inverse was true for PC2. Although human milk remains a source of essential fatty acids, infants could be at risk of inadequate n-3 and n-6 LCPUFA intake through human milk. The differences in the human milk fatty acid profiles also reflect changes in maternal dietary habits in the more recent cohort, which may comprise lower intakes of dietary trans-fatty acids and SFA and higher intakes of vegetable oils.

Fatty acids of human milk - a review

The composition of human milk is the result of the evolution of mammals over millions of years. Among the most important components of milk are fatty acids. Approximately 85% are saturated and monounsaturated fatty acids - the rest are polyunsaturated one. Their role is to provide energy and immunity and to serve as buildings blocks, as well as assisting the hormonal system and the metabolism of fats, carbohydrates and proteins. The structural differences between fatty acids determine their biodiversity and give them particular physiological importance. Correct development of the nervous system, retina and other structures depend on an adequate supply of both these fatty acids during intrauterine development and in the newborn and infant stages. The fats present in milk form milk fat globules - structures that do not appear in milk formula prepared using vegetable oils. Apart from the mother's diet, other sources of fatty acids are endogenous biosynthesis in the mammary gland and the fat deposits from which the fatty acids are released. Evolution of the mother's body has also created adaptive mechanisms that adjust the amount of fatty acids in milk to the state of health and needs of the child. These mechanisms go some way to creating a buffer with regard to dietary shortages experienced by pregnant/breastfeeding women, and optimalise the composition of milk fatty acids depending on the age of the pregnant woman, the birth weight of the infant and the efficiency of the placenta during pregnancy.

Human milk fatty acid composition is associated with dietary, genetic, sociodemographic, and environmental factors in the CHILD Cohort Study

BACKGROUND

Fatty acids are a vital component of human milk. They influence infant neurodevelopment and immune function, and they provide ∼50% of milk's energy content.

OBJECTIVES

The objectives of this study were to characterize the composition of human milk fatty acids in a large Canadian birth cohort and identify factors influencing their variability.

METHODS

In a subset of the CHILD cohort (n = 1094), we analyzed milk fatty acids at 3-4 mo postpartum using GLC. Individual and total SFAs, MUFAs, and n-3 and n-6 PUFAs were analyzed using SD scores and principal component analysis (PCA). Maternal diet, sociodemographic, health, and environmental factors were self-reported. Single-nucleotide polymorphisms were assessed in the fatty acid desaturase 1 (FADS1-rs174556) and 2 (FADS2-rs174575) genes.

RESULTS

Fatty acid profiles were variable, with individual fatty acid proportions varying from 2- to >30-fold between women. Using PCA, we identified 4 milk fatty acid patterns: "MUFA and low SFA," "high n-6 PUFA," "high n-3 PUFA," and "high medium-chain fatty acids." In multivariable-adjusted analyses, fish oil supplementation and fatty cold water fish intake were positively associated with DHA and the "high n-3 PUFA" pattern. Mothers carrying the minor allele of FADS1-rs174556 had lower proportions of arachidonic acid (ARA; 20:4n-6). Independent of selected dietary variables and genetic variants, Asian ethnicity was associated with higher linoleic acid (18:2n-6) and total n-3 PUFAs. Ethnic differences in ARA were explained by FADS1 genotype. Maternal obesity was independently associated with higher total SFAs, the "high medium-chain fatty acid" pattern, and lower total MUFAs. Lactation stage, season, study site, and maternal education were also independently associated with some milk fatty acids. No associations were observed for maternal age, parity, delivery mode, or infant sex.

CONCLUSIONS

This study provides unique insights about the "normal" variation in the composition of human milk fatty acids and the contributing dietary, genetic, sociodemographic, health, and environmental factors. Further research is required to assess implications for infant health.

A Maternal Two-meal Feeding Sequence with Varying Crude Protein Affects Milk Lipid Profile in A Sow-Piglet Model

The effects of a two-meal feeding sequence on production performance and milk lipid profile were investigated. Sixty pregnant sows (d 85 of gestation) were assigned to 3 groups: 2 C group (fed a control crude protein [CP] diet at 0600 and 1500 daily), LH group (fed a low CP diet and a high CP diet at 0600 and 1500), or HL group (fed a high CP diet and a low CP diet at 0600 and 1500). Reproductive performance of sows, and lipid profiles of plasma and milk were measured. Results showed that the HL feeding sequence dramatically increased average piglet weight/litter, average daily gain of piglet/litter, and milk production of sows. LH feeding sequence increased milk fat proportion, and HL feeding sequence significantly increased the proportion of milk MUFA on d 14 and 21 of lactation. Interestingly, the HL feeding sequence also reduced the ratio of C18:1_cis/C18:1_trans in milk, which may account for the greater milk production of sows and growth performance of piglets during lactation. These findings indicated that both the maternal two-meal feeding sequences with varying crude protein improved milk production and milk lipid profiles of sows, which might contribute to improving growth performance of piglets.

Genomics of lactation: role of nutrigenomics and nutrigenetics in the fatty acid composition of human milk

Human milk covers the infant's nutrient requirements during the first 6 months of life. The composition of human milk progressively changes during lactation and it is influenced by maternal nutritional factors. Nowadays, it is well known that nutrients have the ability to interact with genes and modulate molecular mechanisms impacting physiological functions. This has led to a growing interest among researchers in exploring nutrition at a molecular level and to the development of two fields of study: nutrigenomics, which evaluates the influence of nutrients on gene expression, and nutrigenetics, which evaluates the heterogeneous individual response to nutrients due to genetic variation. Fatty acids are one of the nutrients most studied in relation to lactation given their biologically important roles during early postnatal life. Fatty acids modulate transcription factors involved in the regulation of lipid metabolism, which in turn causes a variation in the proportion of lipids in milk. This review focuses on understanding, on the one hand, the gene transcription mechanisms activated by maternal dietary fatty acids and, on the other hand, the interaction between dietary fatty acids and genetic variation in genes involved in lipid metabolism. Both of these mechanisms affect the fatty acid composition of human milk.

New approach shows no association between maternal milk fatty acid composition and childhood wheeze or asthma

BACKGROUND

Previous observational studies have implied breastmilk fatty acid composition may play a role in the development of atopic eczema or atopic sensitization in breastfed infants and toddlers. However, studies investigating associations with wheeze and asthma in later childhood are scarce and did not account for inherent correlation of compositional data. Our aim was to explore the association of maternal milk fatty acid composition with childhood wheezing phenotypes and asthma up to age 13 years using a new statistical approach.

METHODS

Breastmilk was collected 6 weeks and 6 months postdelivery in the Ulm Birth Cohort Study (n=720 and n=454, respectively). Concentrations of 28 fatty acids were measured by high-resolution capillary gas-liquid chromatography. To control for constant-sum constraint, concentration data were transformed using the centered log ratio method. Compositional biplots and correlation matrices were used to group centered log ratio transformed fatty acids. Adjusted risk ratios with parent-reported wheezing phenotypes and doctor-diagnosed asthma were computed using a modified Poisson regression.

RESULTS

We observed no straightforward evidence of associations between overall breastmilk fatty acid composition and specific wheeze phenotypes or doctor-diagnosed asthma.

CONCLUSION

Using appropriate statistical methodology, we report null associations. These findings may partly be attributable to several cohort-specific factors associated with breastfeeding and breastmilk collection. Further studies could improve on ours by analyzing samples of breastmilk and formula and by including all children for whom these are exclusively or together the major source of fatty acids in the first months of life.

Palmitic Acid in Early Human Development

Palmitic acid (16:0) is a saturated fatty acid present in the diet and synthesized endogenously. Although often considered to have adverse effects on chronic disease in adults, 16:0 is an essential component of membrane, secretory, and transport lipids, with crucial roles in protein palmitoylation and signal molecules. At birth, the term infant is 13-15% body fat, with 45-50% 16:0, much of which is derived from endogenous synthesis in the fetus. After birth, the infant accumulates adipose tissue at high rates, reaching 25% body weight as fat by 4-5 months age. Over this time, human milk provides 10% dietary energy as 16:0, but in unusual triglycerides with 16:0 on the glycerol center carbon. This paper reviews the synthesis and oxidation of 16:0 and possible reasons why the infant is endowed with large amounts of fat and 16:0. The marked deviations in tissues with displacement of 16:0 that can occur in infants fed vegetable oil formulas is introduced. Assuming fetal fatty acid synthesis and the unusual delivery of 16:0 in human milk evolved to afford survival advantage to the neonate, it is timely to question if 16:0 is an essential component of tissue lipids whereby both deficiency and excess are detrimental.

Diet-gene interactions and PUFA metabolism: a potential contributor to health disparities and human diseases

The “modern western” diet (MWD) has increased the onset and progression of chronic human diseases as qualitatively and quantitatively maladaptive dietary components give rise to obesity and destructive gene-diet interactions. There has been a three-fold increase in dietary levels of the omega-6 (n-6) 18 carbon (C18), polyunsaturated fatty acid (PUFA) linoleic acid (LA; 18:2n-6), with the addition of cooking oils and processed foods to the MWD. Intense debate has emerged regarding the impact of this increase on human health. Recent studies have uncovered population-related genetic variation in the LCPUFA biosynthetic pathway (especially within the fatty acid desaturase gene (FADS) cluster) that is associated with levels of circulating and tissue PUFAs and several biomarkers and clinical endpoints of cardiovascular disease (CVD). Importantly, populations of African descent have higher frequencies of variants associated with elevated levels of arachidonic acid (ARA), CVD biomarkers and disease endpoints. Additionally, nutrigenomic interactions between dietary n-6 PUFAs and variants in genes that encode for enzymes that mobilize and metabolize ARA to eicosanoids have been identified. These observations raise important questions of whether gene-PUFA interactions are differentially driving the risk of cardiovascular and other diseases in diverse populations, and contributing to health disparities, especially in African American populations.

Impact of maternal diet on human milk composition and neurological development of infants

Maternal nutrition has little or no effect on many nutrients in human milk; for others, human milk may not be designed as a primary nutritional source for the infant; and for a few, maternal nutrition can lead to substantial variations in human milk quality. Human milk fatty acids are among the nutrients that show extreme sensitivity to maternal nutrition and are implicated in neurological development. Extensive development occurs in the infant brain, with growth from ∼ 350 g at birth to 925 g at 1 y, with this growth including extensive dendritic and axonal arborization. Transfer of n-6 (omega-6) and n-3 (omega-3) fatty acids from the maternal diet into human milk occurs with little interconversion of 18:2n-6 to 20:4n-6 or 18:3n-3 to docosahexaenoic acid (DHA) and little evidence of mammary gland regulation to maintain individual fatty acids constant with varying maternal fatty acid nutrition. DHA has gained attention because of its high concentrations and roles in the brain and retina. Studies addressing DHA intakes by lactating women or human milk amounts of DHA at levels above those typical in the United States and Canada on infant outcomes are inconsistent. However, separating effects of the fatty acid supply in gestation or in the weaning diet from effects on neurodevelopment solely due to human milk fatty acids is complex, particularly when neurodevelopment is assessed after the period of exclusive human milk feeding. Information on infant fatty acid intakes, including milk volume consumed and energy density, will aid in understanding of the human milk fatty acids that best support neurological development.

Omega-3 fatty acid deficiency in infants before birth identified using a randomized trial of maternal DHA supplementation in pregnancy

BACKGROUND

DHA is accumulated in the central nervous system (CNS) before birth and is involved in early developmental processes, such as neurite outgrowth and gene expression.

OBJECTIVE

To determine whether fetal DHA insufficiency occurs and constrains CNS development in term gestation infants.

DESIGN

A risk reduction model using a randomized prospective study of term gestation single birth healthy infants born to women (n = 270) given a placebo or 400 mg/day DHA from 16 wk gestation to delivery. Fetal DHA deficiency sufficient to constrain CNS development was assessed based on increased risk that infants in the placebo group would not achieve neurodevelopment scores in the top quartile of all infants in the study.

RESULTS

Infants in the placebo group were at increased risk of lower language development assessed as words understood (OR 3.22, CL 1.49-6.94, P = 0.002) and produced (OR 2.61, CL 1.22-5.58, P = 0.01) at 14 mo, and words understood (OR 2.77, CL 1.23-6.28, P = 0.03) and sentences produced (OR 2.60, CL 1.15-5.89, P = 0.02) at 18 mo using the McArthur Communicative Developmental Inventory; receptive (OR 2.23, CL 1.08-4.60, P = 0.02) and expressive language (OR 1.89, CL 0.94-3.83, P = 0.05) at 18 mo using the Bayley Scales of Infant Development III; and visual acuity (OR 2.69, CL 1.10-6.54, P = 0.03) at 2 mo.

TRIAL REGISTRATION

ClinicalTrials.gov NCT00620672.