Milk nutritional composition and its role in human health


Dairy and milk consumption are frequently included as important elements in a healthy and balanced diet. It is the first food for mammals and provides all the necessary energy and nutrients to ensure proper growth and development, being crucial in respect to bone mass formation. However, several controversies arise from consumption of dairy and milk products during adulthood, especially because it refers to milk from other species. Despite these controversies, epidemiologic studies confirm the nutritional importance of milk in the human diet and reinforce the possible role of its consumption in preventing several chronic conditions like cardiovascular diseases (CVDs), some forms of cancer, obesity, and diabetes. Lactose malabsorption symptoms and cow milk protein allergy are generally considered to be the adverse reactions to milk consumption. The present article reviews the main aspects of milk nutritional composition and establishes several associations between its nutritious role, health promotion, and disease prevention.



Alex’s Notes: There is a lot of controversy about milk and dairy products in general. I remember back when “paleo” was becoming more mainstream that there was a huge backlash against consuming dairy, which quickly turned into an argument against conventional and pasteurized dairy, and now seems to revolve around dairy being fine if it is full-fat, raw, and from pastured animals. No doubt there is evidence in favor or raw unpasteurized milk, and those looking for more information should look at the plethora of information presented by the campaign for Real Milk.

Regardless of the above, the majority of milk consumed in the world is indeed conventional and pasteurized. Does this automatically make milk an unhealthy food? Not at all, and the current study does an excellent job of highlighting the qualities of milk that make it such a powerhouse. This really shouldn’t be so surprising either; I mean milk is designed by nature to grow and develop infants.

On average, bovine milk is composed of 87% water, 4% to 5% lactose, 3% protein, 3% to 4% fat, 0.8% minerals, and 0.1% vitamins. It also supplies about 32g/L of protein divided into an 80/20 ratio of casein and whey proteins, respectively. Better yet, milk proteins are frequently considered the best protein source taking in to account the essential amino acid score and protein-digestibility corrected amino acid score, and the amino acid profile is quite different between the two fractions: Whey is especially rich in branched chain amino acids, i.e., leucine, isoleucine, and valine as well as lysine, whereas casein has a higher proportion of histidine, methionine, and phenylalanine.

Apart from the high-quality and biological value, milk proteins and several bioactive peptides resulting from their enzymatic hydrolysis have shown multiple biological roles that could exert a protective action in human health. These main biological actions include antibacterial, antiviral, antifungal, antioxidant, antihypertensive, antimicrobial, antithrombotic, opioid, and immunomodulatory roles, in addition to improving absorption of other nutrients.

As for the fat composition of milk, it really gets back to knowing where the milk comes from. The amount and composition of milk fatty acid depend on animal origin, stage of lactation, mastitis, ruminal fermentation, and feed-related factors. In fact, milk fatty acids are derived either from feed or from the microbial activity in the rumen, but on average, 70% of fat fraction is composed by saturated fatty acids (SFAs) and 30% unsaturated fatty acids.

Milk has been naturally recognized as a privileged calcium source but it is also a great source of phosphorus, magnesium, zinc, selenium, vitamins A, D, and E and also by water-soluble B complex vitamins such as thiamine and riboflavin.

Unfortunately, there are two main adverse reactions due to milk ingestion. On the one hand are lactose intolerance symptoms that can imply milk avoidance leading the individual to consume other dairy products with less lactose content like yogurt and cheese, and on the other hand, cow milk protein allergy implies a complete avoidance of cow milk products with a prevelance of 2-7.5%.

The above becomes really unfortunate when you then consider the health benefits of milk. For instance, the consumption of milk and dairy products is associated with a markedly reduced prevalence of metabolic syndrome (about a 30% reduction in risk for each half pint – 10 ounces – of milk consumed daily). Dairy intake is also globally recommended as a promoter of good bone health.

To finish up, I feel that the concluding remarks of the article itself are excellent.

“Milk is undoubtedly an omnipresent food in the human diet. It is the first food of mammals and the subject of several health claims. The constant association of milk consumption and a healthy diet has made milk a recommended food. The nutritional richness of milk is unquestionable; it is a good source of high biological value proteins with polyvalent roles in immune function, as well as nutrient transport and absorption and important vitamins and essential minerals. Despite some controversial recent hypotheses about the possible pejorative effects from milk consumption, adding up to lactose malabsorption and intolerance symptoms that would be natural in adulthood, no clear mechanisms and strong evidence have been found, leaving no clear argument to completely exclude a moderate consumption of milk.”

And now the only question that remains is… Got milk?


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