The Globalization of Cow's Milk Production and Consumption: Biocultural Perspectives

Regulation of Key Genes for Milk Fat Synthesis in Ruminants

Milk fat is the most important and energy-rich substance in milk and plays an important role in the metabolism of nutrients during human growth and development. It is mainly used in the production of butter and yogurt. Milk fat not only affects the flavor and nutritional value of milk, but also is the main target trait of ruminant breeding. There are many key genes involve in ruminant milk fat synthesis, including ACSS2, FASN, ACACA, CD36, ACSL, SLC27A, FABP3, SCD, GPAM, AGPAT, LPIN, DGAT1, PLIN2, XDH, and BTN1A1. Taking the de novo synthesis of fatty acids (FA) and intaking of long-chain fatty acids (LCFA) in blood to the end of lipid droplet secretion as the mainline, this manuscript elucidates the complex regulation model of key genes in mammary epithelial cells (MECs) in ruminant milk fat synthesis, and constructs the whole regulatory network of milk fat synthesis, to provide valuable theoretical basis and research ideas for the study of milk fat regulation mechanism of ruminants.

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.

Biosynthesis of milk fat, protein, and lactose: roles of transcriptional and posttranscriptional regulation

The demand for high-quality milk is increasing worldwide. The efficiency of milk synthesis can be improved by taking advantage of the accumulated knowledge of the transcriptional and posttranscriptional regulation of genes coding for proteins involved in the synthesis of fat, protein, and lactose in the mammary gland. Research in this area is relatively new, but data accumulated in the last 10 years provide a relatively clear picture. Milk fat synthesis appears to be regulated, at least in bovines, by an interactive network between SREBP1, PPARγ, and LXRα, with a potential role for other transcription factors, such as Spot14, ChREBP, and Sp1. Milk protein synthesis is highly regulated by insulin, amino acids, and amino acid transporters via transcriptional and posttranscriptional routes, with the insulin-mTOR pathway playing a central role. The transcriptional regulation of lactose synthesis is still poorly understood, but it is clear that glucose transporters play an important role. They can also cooperatively interact with amino acid transporters and the mTOR pathway. Recent data indicate the possibility of nutrigenomic interventions to increase milk fat synthesis by feeding long-chain fatty acids and milk protein synthesis by feeding amino acids. We propose a transcriptional network model to account for all available findings. This model encompasses a complex network of proteins that control milk synthesis with a cross talk between milk fat, protein, and lactose regulation, with mTOR functioning as a central hub.

Old and new stories: revelations from functional analysis of the bovine mammary transcriptome during the lactation cycle

The cow mammary transcriptome was explored at −30, −15, 1, 15, 30, 60, 120, 240, and 300 d relative to parturition. A total of 6,382 differentially expressed genes (DEG) at a false discovery rate ≤0.001 were found throughout lactation. The greatest number of DEG (>3,500 DEG) was observed at 60 and 120 d vs. −30 d with the largest change between consecutive time points observed at −15 vs. 1 d and 120 vs. 240 d. Functional analysis of microarray data was performed using the Dynamic Impact Approach (DIA). The DIA analysis of KEGG pathways uncovered as the most impacted and induced ‘Galactose metabolism’, ‘Glycosylphosphatidylinositol (GPI)-anchor biosynthesis’, and ‘PPAR signaling’; whereas, ‘Antigen processing and presentation’ was among the most inhibited. The integrated interpretation of the results suggested an overall increase in metabolism during lactation, particularly synthesis of carbohydrates and lipid. A marked degree of utilization of amino acids as energy source, an increase of protein export, and a decrease of the protein synthesis machinery as well cell cycle also were suggested by the DIA analysis. The DIA analysis of Gene Ontology and other databases uncovered an induction of Golgi apparatus and angiogenesis, and the inhibition of both immune cell activity/migration and chromosome modifications during lactation. All of the highly-impacted and activated functions during lactation were evidently activated at the onset of lactation and inhibited when milk production declined. The overall analysis indicated that the bovine mammary gland relies heavily on a coordinated transcriptional regulation to begin and end lactation. The functional analysis using DIA underscored the importance of genes associated with lactose synthesis, lipid metabolism, protein synthesis, Golgi, transport, cell cycle/death, epigenetic regulation, angiogenesis, and immune function during lactation.

Dairy and milk consumption and child growth: Is BMI involved? An analysis of NHANES 1999-2004

Humans are unique among mammals in that many consume cow's milk or other dairy products well beyond the traditional age of weaning. Milk provides various nutrients and bioactive molecules to support growth and development, and the question arises as to whether this dietary behavior influences growth parameters. There is evidence that milk makes positive contributions to growth in height, but its associations with other aspects of body size, such as body mass index (BMI), are not well-established. National Health and Nutrition Examination Survey (NHANES) data from 1999 to 2004 and multivariate regression analysis were used to test the hypothesis that milk (g) or total dairy product consumption (kJ) is associated with higher BMI percentile among US White, Black, and Mexican-American children of age 2-4 years (n = 1,493) and 5-10 years (n = 2,526). Younger children in the highest quartile of dairy intake had higher BMIs (beta = 7.5-8.0; P < 0.01) than those in the lowest two quartiles. Controlling for energy intake eliminated differences between QIV and QI. Among children of 5-10 years of age dairy intake had no relationship to BMI. Young children in the highest quartile of milk intake had higher BMIs than all lower quartiles (beta = 7.1-12.8; beta = 6.3-11.8 in energy-controlled models; P < 0.05). Among children of 5-10 years of age, those in QIV for milk intake had higher BMIs than those in QII (beta = 8.3; beta = 7.1 in energy-controlled model; P < 0.01). Controlling for total protein or calcium did not change the results. Milk had more consistent positive associations with BMI than did dairy products, and these were strongest among children of 2-4 years of age.

Sociodemographic variation in knowledge of osteoporosis and locally available calcium-rich foods among urban women living on low incomes in Davao, Philippines

We explored knowledge of osteoporosis and locally available calcium-rich foods among 1,151 urban women in the Philippines and analyzed the cross-sectional associations of their responses to questions about knowledge with their age, educational background, and family income status. In total, 80.3% of the women had heard about osteoporosis; a higher educational background independently predicted this awareness. For knowledge about locally available calcium-rich foods, older age was a positive predictor, whereas higher educational background was a negative predictor. We believe that more emphasis should be placed on locally available foods as part of nutritional education for young urban Filipinos.

Daily calcium intake and physical activity status in urban women living on low incomes in Davao, Philippines: a primary study for osteoporosis prevention

Low calcium intake and physical inactivity are modifiable risk factors of osteoporosis; however, little information is available about the prevalence of these risk factors among urban Filipino women living on low-incomes. The present study, therefore, investigated daily calcium intake, main calcium sources, and physical activity status in this population. The study group comprised healthy women aged in their 30 s who had participated in our previous survey using heel speed of sound (SOS) measurement in Davao, Philippines. The women were stratified into three groups based on SOS score and 20 were randomly selected from each, giving 60 in total. Calcium intake was measured by direct analysis of the food samples collected from 3-days 24 hour-food duplicate method. Physical activity was estimated based on pedometer determined walking steps over 5 days. The median [25%, 75%] calcium intake per day was 289 [225, 434] mg. Traditional foods derived from local small fish and plants were the main calcium sources. The median walking steps per day was 8750 [6920, 10836]. Although three groups did not show significantly different calcium intakes and walking steps, consumption of low-cost small fish and plant foods could be encouraged along with walking in urban Filipino women living on low-incomes.

Osteoporosis in urban post-menopausal women of the Philippines: prevalence and risk factors

Summary

The prevalence of osteoporosis was assessed among post-menopausal women dwelling in an urban community of Davao, Philippines using quantitative ultrasonic bone densitometry and its predictors were investigated. The prevalence of osteoporosis was 19.8%. Advancing age, lower body weight, and higher educational attainment were identified as the independent predictors of osteoporosis.

Introduction

This cross-sectional study assessed the prevalence of osteoporosis among post-menopausal women dwelling in an urban community of the Philippines and investigated the risk factors for osteoporosis using a quantitative ultrasonic bone densitometer.

Methods

The study site was an area with high population density in Davao, the Philippines. Data collection was based on a structured questionnaire interview, and measurements of body size and speed of sound (SOS) at the calcaneus. The SOS T-score was calculated using the young adult mean (YAM) SOS based on data from 905 women aged 20 years and over residing in the community. The data for 339 post-menopausal women were analyzed to identify the prevalence of osteoporosis and its predictors in this study. The predictors of osteoporosis were determined by logistic regression analysis.

Results

The majority of the women lived on low-incomes. The prevalence of osteoporosis was 19.8% in post-menopausal women. Age in 1 year increments (odds ratio [OR] 1.168), body weight (OR 0.954), and duration of education in years (OR 1.132) were predictors of osteoporosis.

Conclusions

This study identified body weight as a modifiable risk factor of osteoporosis for post-menopausal women. Longitudinal observation of the same participants will be necessary to confirm these findings.