Hormones in milk

Metabolic hormones in human breast milk are preserved by high hydrostatic pressure processing but reduced by Holder pasteurization

In human milk banks (HMBs), donor milk (DM) is commonly sterilized by Holder pasteurization (HoP). High hydrostatic pressure (HHP) processing is an innovative, alternative method for DM sterilization. We evaluated the impact of HHP processing on the concentration of seven metabolic milk hormones. Eight samples of raw DM were aliquoted. One aliquot was sterilized by HoP (62 °C for 30 min), and another was processed by HHP (350 MPa at 38 °C). Compared with raw DM, HoP milk displayed reduced concentrations of insulin, nesfatin-1, cortisol, leptin, apelin and GLP-1, though adiponectin levels were unchanged. HHP processing maintained the levels of insulin, nesfatin-1, cortisol and leptin at their initial levels in raw DM, reduced apelin and adiponectin levels, but increased GLP-1 level. Sterilization of DM by HHP thus preserves the main metabolic hormones in human milk, underlining the interest of this method for use in HMBs.

Naturally occurring hormones in foods and potential health effects

Hormones and hormone-like substances, for example, phytoestrogens, are food components that can be endogenously produced by a food source or occur secondary to farming practices. The hormone content of foods has been studied for decades, and safety evaluations in the United States and Europe indicate that naturally occurring hormones found in foods are safe for human consumption. More recent studies have focused on the role of certain hormones found in specific foods (e.g. dairy or soy) and their potential health effects. However, limited summaries exist on food content of hormones and hormone-like phytoestrogens in the context of a comprehensive US diet and implications, if any, of their daily consumption for overall health. This review provides an outline of hormone biosynthesis and functions in the body; discusses the more commonly studied, naturally occurring hormones in food and their biological role within food; estimates relative dietary contribution and when available, bioavailability, of naturally occurring food hormones; and summarizes the potential health associations of their intake in food. Based on the review of the scientific literature, the hormone content of typical serving sizes of commonly consumed foods is undetectable or in quantities that fall well within safety guidelines without any evidence for adverse effects on health.

Assessment of pregnancy-associated glycoprotein profile in milk for early pregnancy diagnosis in goats

Objective

This study was conducted to assess the level of pregnancy-associated glycoprotein (PAG) in whole and skim milk samples, and its suitability for early pregnancy diagnosis in goats.

Methods

A two-step sandwich enzyme-linked immunosorbent assay (ELISA) system for estimation of milk PAG was developed and validated, which employed caprine-PAG specific polyclonal antisera. Whole and skim milk samples (n = 210 each) from fifteen multiparous goats were collected on alternate days from d 10 to d 30, and thereafter weekly till d 51 post-mating. PAG levels in milk samples were estimated by ELISA and the pregnancies were confirmed at d40 post-mating by transrectal ultrasonography (TRUS).

Results

The level of PAG in whole and skim milk samples of both pregnant and non-pregnant goats remained below the threshold values until d 24 after mating. Thereafter, PAG concentration in whole and skim milk increased steadily in pregnant goats, whereas it continued below the threshold in non-pregnant does. The PAG profiles in whole and skim milk of pregnant goats were almost similar and exhibited strong positive relationship (r = 0.891; p<0.001). Day 26 post-mating was identified as the first time-point for significantly (p<0.05) higher milk PAG concentration in pregnant goats than to non-pregnant goats. When compared to TRUS examination for pregnancy diagnosis, the accuracy and specificity of PAG ELISA using whole and skim milk samples were 94.5% and 95.4%; and 95.3% and 100%, respectively. The high values of area-under-curve (0.904 [whole milk] and 0.922 [skim milk]), demonstrate outstanding discrimination ability of the milk assays. Among the sampling dates chosen, d 37 post-mating was identified as the best suitable time point for collection of milk samples to detect pregnancy in goats.

Conclusion

The PAG concentration in whole and skim milk of goats collected between days 26 and 51 post-breeding can be used for the accurate prediction of pregnancy and may be useful for assisting management decisions in goat flocks.

A Fluorescence Polarization Assay To Detect Steroid Hormone Traces in Milk

Steroids are a class of hormones improperly used in livestock as growth-promoting agents. Due to their high risk for human health, the European Union (EU) has strictly forbidden the administration of all natural and synthetic steroid hormones to food-producing animals, and the development of new rapid detection methods are greatly encouraged. This work reports a novel fluorescence polarization assay, ready to use, capable of detecting 17β-estradiol directly in milk samples with a low limit of detection of <10 pmol. It is based on the coupling of monospecific antibodies against 17β-estradiol and fluorophores, capable of modulating the fluorescence polarization emission on the basis of the specific binding of antibodies to fluorescence-labeled 17β-estradiol derivative. The successful detection of 17β-estradiol has disclosed the development of an efficient method, easily extensible to any food matrix and having the potential to become a milestone in food quality and safety.

Colostrogenesis: IgG1 transcytosis mechanisms

Biological transport of intact proteins across epithelial cells has been documented for many absorptive and secretory tissues. Immunoglobulins were some of the earliest studied proteins in this category. The transcellular transport (transcytosis) of immunoglobulins in neonatal health and development has been recognized; the process is especially significant with ungulates because they do not transcytose immunoglobulins across the placenta to the neonate. Rather, they depend upon mammary secretion of colostrum and intestinal absorption of immunoglobulins in order to provide intestinal and systemic defense until the young ungulate develops its own humoral defense mechanisms. The neonatal dairy calf's ability to absorb immunoglobulins from colostrum is assisted by a ~24 h "open gut" phenomenon where large proteins pass the intestinal epithelial cells and enter the systemic system. However, a critical problem recognized for newborn dairy calves is that an optimum mass of colostrum Immunoglobulin G (IgG) needs to be absorbed within that 24 h window in order to provide maximal resistance to disease. Many calves do not achieve the optimum because of poor quality colostrum. While many studies have focused on calf absorption, the principal cause of the problem resides with the extreme variation (g to kg) in the mammary gland's capacity to transfer blood IgG1 into colostrum. Colostrum is a unique mammary secretory product that is formed during late pregnancy when mammary cells are proliferating and differentiating in preparation for lactation. In addition to the transcytosis of immunoglobulins, the mammary gland also concentrates a number of circulating hormones into colostrum. Remarkably, the mechanisms in the formation of colostrum in ungulates have been rather modestly studied. The mechanisms and causes of this variation in mammary gland transcytosis of IgG1 are examined, evaluated, and in some cases, explained.

Organic foods: health and environmental advantages and disadvantages

The US market for organic foods has grown from $3.5 billion in 1996 to $28.6 billion in 2010, according to the Organic Trade Association. Organic products are now sold in specialty stores and conventional supermarkets. Organic products contain numerous marketing claims and terms, only some of which are standardized and regulated. In terms of health advantages, organic diets have been convincingly demonstrated to expose consumers to fewer pesticides associated with human disease. Organic farming has been demonstrated to have less environmental impact than conventional approaches. However, current evidence does not support any meaningful nutritional benefits or deficits from eating organic compared with conventionally grown foods, and there are no well-powered human studies that directly demonstrate health benefits or disease protection as a result of consuming an organic diet. Studies also have not demonstrated any detrimental or disease-promoting effects from an organic diet. Although organic foods regularly command a significant price premium, well-designed farming studies demonstrate that costs can be competitive and yields comparable to those of conventional farming techniques. Pediatricians should incorporate this evidence when discussing the health and environmental impact of organic foods and organic farming while continuing to encourage all patients and their families to attain optimal nutrition and dietary variety consistent with the US Department of Agriculture's MyPlate recommendations. This clinical report reviews the health and environmental issues related to organic food production and consumption. It defines the term "organic," reviews organic food-labeling standards, describes organic and conventional farming practices, and explores the cost and environmental implications of organic production techniques. It examines the evidence available on nutritional quality and production contaminants in conventionally produced and organic foods. Finally, this report provides guidance for pediatricians to assist them in advising their patients regarding organic and conventionally produced food choices.

The presence of the peptides apelin, ghrelin and nesfatin-1 in the human breast milk, and the lowering of their levels in patients with gestational diabetes mellitus

Numerous bioactive peptides (such as ghrelins) have been identified in breast milk but there is no information concerning apelin and nesfatin-1. Therefore, present study was designated to explore whether breast milk contains apelin and nesfatin-1, to determine the concentrations and to compare these with serum levels. In addition, the concentrations of these peptides were compared in patients with gestational diabetes and normal lactating samples. Furthermore, this study explored the effectivity of various commercial diagnostic kits for determining ghrelin concentrations in breast milk. Ten gestational diabetic lactating women (29.1±2.2 years old and BMI: 33.2±4.8) and 10 control lactating women (28.2±1.8 years old and BMI: 39.48±1.7) were enrolled in the study. An ELISA was used to determine concentrations of apelin-36 and -12, nesfatin-1, and acylated and desacylated ghrelin in serum, colostrum and mature milk. Serum apelin-36 and -12 concentrations were correlated with colostrum and mature milk, and the same trends were observed for nesfatin-1. Apelins and nesfatin-1 concentrations were higher in mature milk than in colostrum (P<0.05). The concentration of apelins, ghrelins and nesfatin-1 in serum and milk in gestational diabetic lactating women was lower than in control samples. The majority of ghrelin circulating and in milk was the free form (desacylated) in both groups of women. This is the first report to describe the presence of apelins and nesfatin-1 in breast milk. It is suggested that the source of ghrelins, apelins and nesfatin-1 in breast milk is likely to be breast tissue (autonomous production). These bioactive peptides found in breast milk could be important for growth, energy regulation and maturation of the gastrointestinal system in neonates.

Contrasting effects of estradiol and progesterone on respiratory pattern and hypoxic ventilatory response in newborn male rats

We tested the hypothesis that postnatal exposure to progesterone or estradiol exerts distinct effects on respiratory control, apnea frequency, and on hypoxic ventilatory response (HVR). To this aim, we assessed breathing pattern using whole body plethysmography in normoxia and during a sustained hypoxic exposure (10% O(2)-30min) in 10-day-old male rats raised by dams implanted with osmotic minipumps delivering either estradiol (E(2), 7.0microgday(-1)), estradiol+progesterone (E(2)+P, 7.0+70microgday(-1)) or vehicle (propylene glycol) at a regular flow rate throughout postnatal days 1-14. Compared to vehicle, E(2) and E(2)+P pups had a reduced ventilation, metabolic rate and rectal temperature. HVR was specifically increased in E(2)+P pups compared to controls and E(2) pups. On the contrary, both E(2) and E(2)+P pups did not reduced metabolism as much as controls during hypoxic exposure, and the decrease in rectal temperature was abolished. Surprisingly, E(2)+P pups showed a dramatic elevation of sigh frequency, while progesterone (in E(2)+P compared to E(2) and Veh pups) reduced apnea frequency. These findings are relevant to better understand the role of placental steroids on respiratory and metabolic control during early development in rats, and could ultimately contribute to a better understanding of specific respiratory control disorders in preterm neonates, which are chronically deprived from placental steroids exposure.

Progesterone increases hypoxic ventilatory response and reduces apneas in newborn rats

We hypothesized that progesterone may enhance the hypoxic ventilatory response and reduce the occurrence of apneas in newborn male rats. We studied 10-day-old rats chronically exposed to progesterone (Prog) or vehicle through the milk of lactating mothers. Respiratory and metabolic recordings were performed using whole body plethysmography under normoxia and during hypoxic exposure (10% O(2)--30 min). While progesterone did not alter baseline breathing and metabolic rate, it increased hypoxic ventilatory response particularly by limiting the magnitude of the ventilatory roll-off during the second phase of the hypoxic ventilatory response (i.e. following 5 min of exposure). In parallel, progesterone lowered the number of spontaneous apneas and drastically reduced the occurrence of post-sigh apneas during hypoxic exposure by limiting the time of the post-sigh expiratory pause. Following domperidone injection (used to block peripheral D2 dopamine receptor), minute ventilation increased in Veh pups and the number of spontaneous apneas decreased. These responses were not observed in Prog pups, suggesting that progesterone reduces peripheral dopaminergic inhibition on breathing. We conclude that progesterone is a potent stimulant of hypoxic ventilatory response in newborn rats and effectively reduces the occurrence of apneas.

Naturally occurring estrogens in processed milk and in raw milk (from gestated cows)

The occurrence of the steroid hormones estrone (E1), 17alpha-estradiol (alphaE2), 17beta-estradiol (betaE2), and estriol (E3) in processed bovine milk with different fat contents and in raw milk from (non)gestated cows was investigated. Following liquid extraction, optional enzymatical deconjugation, C18 solid-phase extraction, and derivatization, estrogens were analyzed using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Free and deconjugated E1 (6.2-1266 ng/L) was the major estrogen followed by alphaE2 (7.2-322 ng/L) and betaE2 (5.6-51 ng/L), whereas E3 was detected regularly at the detection limit of 10 ng/L. The lowest and highest concentrations were determined in raw milk from nonpregnant and from cows in the third trimester of gestation, respectively. The estrogen concentration in processed milk coincides with that of raw milk between first and second trimesters, reflecting the contribution of lactating pregnant cows to the final consumable product. The daily intake of total investigated estrogens through milk is 372 ng, which is dramatically more than currently recognized.

Milk protein-derived opioid receptor ligands

Milk is mammalian characteristic and is of particular importance for humans: Mother's milk or its substitutes from cows' milk are absolutely essential nutriments for the neonate and cows' milk also represents a basic foodstuff for adults. However, in addition to their well-known nutritive role, milk constituents apparently are also able to carry specific information from the milk producer's to the milk receiver's organism: Thus, a number of milk protein fragments has been shown to behave like opioid receptor ligands able to address opioidergic systems in the adult's or in the neonate's organism. With respect to the proteins, which they are derived off these peptides have been named alpha-casein exorphins or casoxin D (alpha-casein), beta-casomorphins or beta-casorphin (beta-casein), casoxin or casoxin A, B, or C (k-casein), alpha-lactorphins (alpha-lactalbumin), beta-lactorphin (beta-lactoglobulin) or lactoferroxins (lactoferrin). Only casoxins and lactoferroxins display antagonistic properties; the other peptides behave like opioid receptor agonists. Most of the information available so far has been collected about beta-casomorphins. These peptides obviously can be released from beta-casein in the adult's or in the neonate's organism, where they might elicit opioid effects in the frame of a regulatory role as "food hormones". Several synthetic beta-casomorphin derivatives have been shown to be highly specific and potent mu-type opioid receptor ligands which frequently have been used as standard tools in opioid research.

Isoflavones, soy-based infant formulas, and relevance to endocrine function

For more than 60 years, soy-based infant formulas have been fed to millions of infants worldwide and studied in controlled clinical research. These products provide essential nutrients required for normal growth and development. The safety of isoflavones in soy-based products, including infant formulas, has been questioned recently owing to reports of possible endocrine effects in animals and in cultured cells. The literature offers no evidence of endocrine effects in humans from infant consumption of modern soy-based formulas. Growth is normal and no changes in the timing of puberty or in fertility rates have been reported in humans who consumed soy formulas as infants. Consequently, soy-based infant formulas continue to be a safe, nutritionally complete feeding option for most infants.

Bioactive steroids as contaminants of the common carbon source galactose

Most inducible expression vectors for the budding yeast Saccharomyces cerevisiae are based on galactose-inducible promoters. Yeast has been increasingly used to study vertebrate steroid receptors because of its powerful genetics. In principle, both regulatory systems are compatible and can be combined in the same strain. However, we found that commercial galactose can be contaminated by bioactive estrogen and progesterone at concentrations that are sufficient to fully activate their cognate receptors. Since steroids can elicit biological responses in pathogenic fungi and possibly other microorganisms, such contaminants in a commonly used fermentable carbon source may need to be screened for.

Dairy products and breast cancer: the IGF-I, estrogen, and bGH hypothesis

Research on the role of dietary factors in breast cancer causation has focused predominantly on fat intake. While some studies have examined associations between breast cancer rates and consumption of whole milk, there has been less attention given to dairy products in general. Dairy products contain both hormones and growth factors, in addition to fat and various chemical contaminants, that have been implicated in the proliferation of human breast cancer cells. This literature review evaluates the epidemiological and mechanistic evidence linking dairy consumption with breast cancer risk.

Factors affecting insulin-like growth factor-I concentration in bovine milk

To establish the naturally occurring range of insulin-like growth factor-I concentrations in bovine milk, samples from individual cows (n = 409) managed on five Missouri dairy herds were assayed. Parity, stage of lactation, and farm affected milk insulin-like growth factor-I concentration. Milk insulin-like growth factor-I concentration was higher in early lactation than mid and late lactation with concentrations in multiparous cows exceeding those in primiparous cows. Insulin-like growth factor-I concentration was negatively correlated to milk production the day of sample collection (r = -.15) and not correlated to predicted 305-d milk yields. Unprocessed bulk tank milk samples (n = 100) from a commercial processing plant had a mean concentration of insulin-like growth factor-I in milk of 4.32 ng/ml with a range of 1.27 to 8.10 ng/ml. This distribution was similar to the range detected in samples from individual cows, but values were lower than those reported for human milk. Concentration of insulin-like growth factor-I in milk was not altered by pasteurization (at 79 degrees C for 45 s). However, insulin-like growth factor-I was undetectable in milk heated to temperatures (121 degrees C for 5 min) required for infant formula preparation or in commercially available infant formula. These data indicated that insulin-like growth factor-I is a normal but quantitatively variable component of bovine milk that is not destroyed by pasteurization but is undetectable in infant formula. Concentration of insulin-like growth factor-I in bovine milk is lower than concentrations reported for human milk yet similar to those reported for human saliva.(ABSTRACT TRUNCATED AT 250 WORDS)

Changes in concentrations of insulin-like growth factor 1, insulin and growth hormone in bovine mammary gland secretion ante and post partum

Concentrations of insulin-like growth factor 1 (IGF-1), insulin and growth hormone were measured in the secretion of the bovine mammary gland from day 70 ante partum until 6 d post partum. Highest levels were found during the last 2 weeks ante partum followed by a rapid decrease during the first milkings post partum. The association of IGF-1 with its binding proteins in milk was analysed and striking differences were found in the distribution of bound and free IGF-1. IGF-1 appeared mainly in the bound form (91%) at days 40-2 ante partum. Free IGF-1 preponderated in the first milkings post partum (73%) and changed again to about 85% in the bound form after day 4 post partum. A slightly acidic pH (6.3) of the secretion was correlated with high amounts of free IGF-1. Gel filtration experiments revealed a possible pH-dependent mechanism for the binding of IGF-1 to its binding proteins in milk.

Neuroendocrine peptides in milk

Milk, which is a mammal-specific biologic fluid, contains several neuroendocrine peptides at concentrations higher than those found in plasma. These neuroendocrine peptides can be synthesized or processed in the mammary gland or excreted into milk through various pathways. In addition, certain milk proteins, notably casein, can be enzymatically processed to release "exorphins," peptides with opioid activities. In suckling mammals, hormones and neuropeptides are absorbed through the gastrointestinal tract and appear intact in the plasma. This absorption is age dependent and could have physiologic significance in neonatal development.

Beta-endorphin-like and alpha-MSH-like immunoreactivities in human milk

We measured with radioimmunoassay the beta-endorphin-like and alpha-MSH-like immunoreactivities in milk and plasma of 8 lactating women. Mean beta-endorphin concentrations ( +/- SD) were 16.6 +/- 6.7 fmol/ml in milk and 9.9 +/- 4.1 fmol/ml in plasma. alpha-MSH concentrations (mean +/- SD) were 39.4 +/- 15.5 pg/ml in milk and 18.2 +/- 8.4 pg/ml in plasma. The concentrations of both peptides in milk were significantly (p less than 0.05) higher than in plasma. No significant correlation between milk and plasma concentrations of these peptides was found.

Growth hormone releasing factor and somatostatin concentrations in the milk of lactating women

The concentrations of growth hormone releasing factor (GRF) and somatostatin, two hypothalamic neuropeptides involved in the regulation of growth hormone secretion, were measured in human milk samples. The study was performed in healthy women within 48 h of delivery or during established lactation (between 1 and 64 weeks post delivery). No statistically significant correlation was found between the levels in milk of either of the neuropeptides and the gestational age at birth. However, lower values of GRF (23 +/- 4.7 pg/ml vs. 40.5 +/- 4.9 pg/ml) were found in milk obtained during established lactation than in milk obtained close to delivery. A positive correlation was observed between somatostatin and GRF concentrations in milk. The possible involvement of milk neuropeptides in the control of growth hormone secretion in the neonate, as well as in the regulation of other physiological processes, are evaluated.