A Study of the Variations in the Chemical Composition of Normal Human Colostrum and Early Milk

Casein and Whey Protein in the Breast Milk Ratio: Could It Promote Protein Metabolism Enhancement in Physically Active Adults?

Due to the utilization of milk proteins such as whey protein (WP) and casein as sports nutrition ergogenic aids, the present study investigated the effects of the association of WP and casein in a ratio of 80:20, a similar ratio of human breast milk, on blood branched-chain amino acid (BCAA) profiles, markers of protein metabolism and delayed onset muscle soreness (DOMS), after a single bout of resistance exercise. A double-blind, crossover and acute study was carried out with ten men (age 29 ± 8 years; BMI: 25.4 ± 2.9 kg/m²; 77 ± 12 kg; 1.74 ± 0.09 m); each one consumed the following supplements randomly, one per session: WP, CAS (casein), WP/CAS (80% WP/20% CAS), CAS/WP (80% CAS/20% WP) and PLA (placebo). They were also subjected to the following evaluations: the one repetition maximum (1RM) test; resistance training session; blood extraction during each session to determine the BCAA profile; two food records; 3-day evaluation of DOMS (24 h, 48 h and 72 h) and nitrogen balance in each treatment. The intervention resulted in similar nitrogen urinary, creatinine and urea plasma levels and showed a positive nitrogen balance in all the trials. Regarding the BCAAs, the peak occurred at 60 min post-ingestion and remained higher until 120 min for WP, WP/CAS and CAS/WP. The DOMS was significantly lower for WP, WP/CAS and CAS/WP compared to the CAS and PLA treatments. There were no advantages in the association of WP and CAS in the BCAAs profile when compared to WP itself, but it induced a lower DOMS compared to CAS and PLA (Clinical Trial registration number: clinicaltrials.gov, NCT04648384).

Classic studies of mammary development and milk secretion: 1945 - 1980

On June 20, 1947 a meeting at the Royal Society of Medicine in London was entitled "Discussion on Some Recent Developments in Knowledge of the Physiology of the Breast". The major questions outlined by the speakers were: how does the structure of the breast change with reproductive stage? What is the role of the basal cell layer in the mammary epithelium? How is milk composition related to diet? And what is the basic physiology of milk secretion including its hormonal regulation? All these questions were attacked vigorously in laboratories mostly in England and the United States, but researchers in France, Germany, and Austria also weighed in. Our purpose in this edition of the Journal is to show, through the presentation of seminal papers and key references, how the research of that period, prior to the molecular revolution of the last three decades, laid the groundwork for our current understanding of the morphology, developmental biology, and physiology of the functional mammary gland. This knowledge provides the groundwork for our current research into the molecular mechanisms involved in milk secretion and its regulation.

155. The composition of mare's milk. II. The variation in composition during lactation. III. The influence of intra-mammary pressure on the composition of milk with special reference to the mare and cow

1. The investigation was for the purpose of ascertaining the cause of the variations previously noted by the author as occurring in mare's milk.

2. Determinations have been made of the composition of the milk of eight Shetland ponies and one Clydesdale mare throughout the lactation period, with observations on the milk of numerous thoroughbred mares. The constituents estimated were the total solids, solids-not-fat, protein, fat, lactose, total ash, CaO, P2O5, and chlorine. The CaO, P2O5and chlorine percentages in the ash of the milk were also determined. The freezing-point and pH were recorded in a number of samples. The animals were kept under natural conditions at grass.

3. It was found that as lactation advanced the percentage of total solids, lactose and fat of the milk increased in a linear manner, whereas the percentage of solids-not-fat, protein, CaO, and P2O5decreased linearly.

4. The regression of the total solids and the chlorine was parabolic in character as also was that of the chlorine-lactose index.