A consequence of the obesity epidemic, which began in the United States during the 1980s, is the targeting of milk as a possible contributing factor for weight gain, metabolic syndrome, and cardiovascular disease, due to its high fat content. As a result, in the mid 1990’s, the U.S. Department of Agriculture recommended switching to reduced-fat milk, and the consumption of whole milk fell drastically. As this was happening, the growth of soy and soy “milk” paved the way for other milk-alternative beverages, such as, almond, coconut, and cashew “milk”, and consumers began to question whether it was healthy or natural for human to consume animal milk at all. In addition to fears that milk contributed to obesity, and the metabolic disorders that go along with excessive weight gain, milk allergy, and anecdotal reports of milk worsening rhinitis, and triggering asthma began to surface.

However, in the past decade, several studies have reported beneficial health effects of cow’s milk in the prevention of the development of asthma and allergy in children, as well as, protection against cancer, obesity, diabetes, and cardiovascular disease in adults.

Further investigation into the composition of milk, and its components haves revealed that it may be time to reconsider the health benefits of milk again. In addition to its nutritional value, the ingredients in milk possess bioactive functionality. The protein, lipid, and saccharide components of milk contain molecules that are anti-inflammatory, anti-microbial, and immunogenic (capable of modulating the immune system), in addition to improving the body’s response to insulin and regulation of fat.

Cow’s milk is Comparable to Human Breast Milk

Milk is a biological fluid produced by mammals to provide nutrition and immunity to newborns. Although cow’s milk may be designed to feed a calf, it is actually very similar in composition to human breast milk. Milk is a very complex fluid, and both milks contain over 400 ingredients. The difference between human and bovine milk lies in the concentration of their components. For example, human milk contains 10 times the amount of lactoferrin, osteopontin, and lysozme, as cow’s milk, but 10 times less lactoperoxidase and α-2-casein.

Here is a breakdown of the differences between human breast milk and cow’s milk:

Proteins. Cow’s milk contains beta-lactoglobulin and  α-2-casein, which are not present in human milk. These two proteins are the components responsible for eliciting an immune response in individuals with Cow’s milk allergy.

Vitamins & Minerals. Human milk contains more vitamin A and D, than cow’s milk. However processed milk is supplemented with both of these vitamins, and naturally has more calcium and zinc than human milk.

Fats. In regards, to fat composition, human milk has a greater concentration of linoleic acid and conjugated linoleic acid, while cow’s milk has a relatively high concentration of very short-chain fatty acids, which are not present in human milk.  Cow’s milk does contains additional conjugated linoleic acids.  Rumenic acid (a conjugated linoleic acid) and its precursor, vaccenic acid, are not innately produced by humans. However, they can be found in the breast milk of nursing women who acquire it from consuming cow’s milk.

Sugars. The major difference between cow’s milk and human milk is the number and concentration of oligosaccharides. Human milk is sweeter than cow’s milk. It has more oligosaccharides, and these sugars are present at higher concentrations. Human milk consists of the neutral and acid oligosaccharides containing, fucose and sialic acid, respectively. Cow’s milk contains miniscule amounts of fucose, and has less oligosaccharides overall. *fucose should not be confused with fructose.

Due to the almost identical composition of cow’s milk to humans milk, it is a practical and nutritional food suitable for human consumption.

Benefits of Drinking Milk

Cow’s Milk, Allergies, & Asthma

There are many benefits to drinking cow’s milk that goes beyond nutrition. The consumption of cow’s milk can prevent the development of allergies in humans. Contrary to anecdotal belief, milk consumption does NOT trigger or intensify asthma or IgE-mediated environmental/seasonal allergies.

Studies have shown that ingestion of farm milk decreases the development of asthma. Farm milk (milk in its raw form) contains many proteins and other components that can help protect against the development of asthma in infants and also adults. Unfortunately, raw farm milk is not safe to drink, as it can contain harmful bacteria. While pasteurization kills the pathogens in milk, making it safe for consumption, the bioactive proteins on the fat portion of milk is broken down. This suggests that the removal of fat from milk, may not be as good of a practice after-all, as it results in the  removal of some of the beneficial components of milk. Although some proteins and fatty acids are denatured or removed, processed milk still retains most of its benefits, in this regard.

The allergenic proteins lacto-albumin, beta-lactoglobulin, and caseins, in cow’s milk are only harmful to those who have Cow’s Milk Allergy, which is an inflammatory response to these specific proteins in cow’s milk.  It is worth nothing that while a common food allergy in young children, Cow’s milk Allergy is rare in adults, and the majority of children with the condition outgrow it by the age of five.

Bioactive nature of milk

As mentioned before, the proteins, fats, sugars, and vitamins, in milk do not only serve as nutrients, they also possess biologically functional activity. As bioactives, these components protect against disease.

Proteins found in milk have antimicrobial and anti-allergenic properties.

Proteins in milk such as lactoferrin, lactoadherin, lysozyme, cytokines and immunoglobulins all have beneficial immune-related functions. Cytokine TGF-β is found in both human breast milk and cow’s milk, and is protective against allergy-related disorders that develop in infancy and early childhood, such as asthma and food allergies. Immunoglobulins IgG and IgA present in cow’s milk is analogous to human IgA and IgG, and these substances help prime the immune system against IgE mediated allergies. Interestingly, cow’s milk contains allergen-specific IgG to inhalational allergens, such as, dust mites, toxic black mold, and grass and birch tree pollen. When ingested, the IgG in milk binds and neutralize these allergens. Milk Immunoglobulins also act against E.Coli’s enterotoxicity.

Lactoferrin, an iron scavenging compound, helps to regulate the transport and availability of iron within the gut. Iron plays an important role in cellular respiration, but iron overload can lead to production of toxic reactive oxygen species and oxidative stress. Lactoferrin can also prevent the growth of iron-dependent pathogens. Lysozyme also has antimicrobial properties.

Milk Hormones regulate G.I. tract & wards off obesity/diabetes; risk factors for Cardiovascular disease.

Hormones naturally present in milk are also beneficial. Motilin, a hormone secreted in the small intestine, and Ghrelin, a motilin related peptide secreted in the stomach and by the pancreas, regulate gastrointestinal motility. The two are involved in increasing gastric emptying, and stimulating the release of peptides from various tissues in the body. These milk hormones have been shown to relieve constipation in chronically constipated individuals, by increasing defecation and stool softness. When given fat-free milk, the levels of motilin and ghrelin were increased in constipated individuals, and they saw significant relief or resolution of their constipation.

Ghrelin also plays a pivotal role in obesity and diabetes. Ghrelin is known to regulate the balance of glucose in the body by regulating insulin secretion and sensitivity in pancreatic cells, as well as glucose release from the liver. Ghrelin has two forms, acylated and de-acylated. These two forms of ghrelin have opposition functions. Acylated ghrelin is responsible for stimulating the appetite and therefore increases body weight and fat, while de-acylated ghrelin reduces food intake, and decreases glucose release and insulin.  Interestingly, total ghrelin—the sum of the two ghrelins—is reduced in obesity and insulin resistance, and there is an imbalance in favor of the deleterious form of ghrelin. Drinking  milk, can offset this imbalance.

Whey proteins are also able to stimulate the production and activity of insulin.

Sugars & Fatty acids are beneficial too

Milk oligosaccharides participate in preventing bacterial infections. By acting as decoy receptors, they prevent the adhesion pathogenic bacteria to the intestinal wall. Oligosaccharides also serve as substrates for the growth of good bacteria. Lactose and sialyllactose promote the growth of beneficial bifidobacteria in the intestinal tract. In turn, these sugars are metabolized by bifidobacteria and other fermenting bacteria into short-chain fatty acid, such as acetate, butyric acid, and propionate. These fatty acids decrease the pH within the colon, making an inhospitable environment for pathogens to thrive.

Other fatty acids; rumenic and vaccenic acid, inhibit pro-inflammatory cytokine production, and therefore prevent inflammation (a chronic inflammatory state within the body is associated with the development of insulin resistant diabetes and cardiovascular disease).

Cow’s milk for Babies & Adults

Human milk contains at least ten-times the amount of lactoferrin as cow’s milk, as well as more vitamins A and D.  Human babies require a lot of iron in their diet, and vitamins A and D are vital to both children and adults.

Cow’s milk is not recommended for newborns before the age of 6 to 12 months due to its low iron content, as well as, the prevalence of Cow’s Milk Allergy in the first year of life.  However, after that, milk is a suitable substitute for human breast milk for infants.  The similar oligosaccharides found in milk, compensate for those found in human breast milk, and help to maintain a healthy intestinal microbiota, by supporting the growth of bifidobacteria which prevents the growth of the harmful bacteria, C. difficile and E. coli. Babies who were not breast-fed, or who were given formula that did not contain cow’s milk components, were found to have lower amounts of bifidobacteria in their gut.

While breast milk is the preferable and best way to feed a newborn, giving cow’s milk as a supplement to breast milk, or a compliment to solid foods in infants and toddlers is very beneficial.  Transforming growth factor-beta (TGF-β), a cytokine, which is also found in breast milk, protects against allergy-related disorders in infancy and early childhood, by inducing oral tolerance to allergens. Introducing cow’s milk during infancy, not only prevents the development of asthma, environmental allergies, and atopic dermatitis, it also prevent the development of Cow’s Milk Allergy itself.

Adults

Cow’s milk is a good source of fat soluble vitamins and calcium. Cow’s milk is also commonly fortified with vitamin’s A and D. These two vitamins play important roles in supporting a healthy immune system. Vitamin A plays a role in the development of T cells, which produce the allergy neutralizing immunoglobulins IgA and IgG, and vitamin D deficiency is known to cause immune suppression, which is a risk factor for developing allergies.

Besides contributing to bone health, and preventing allergies, milk bioactives may reduce the risks of some cancers, insulin resistance, and cardiovascular disease. This is because the calcium found in milk along with other peptides may reduce blood pressure and cholesterol, while fatty acid components improve insulin action. Conjugated fatty acids, such as Linoleic acid may have anti-carcingogenic, anti-artherogenic, anti-lipogenic, and anti-inflammatory action. Milk also improves the body’s ability to use folate, which plays a role is preventing heart attacks.

In regards to cardiovascular health, fermented milk and fermented milk products (kefir, yogurt, sour cream, cottage cheese…) offer the greatest value. Fermented milk is made using probiotic bacteria, which increases the antioxidant activity and fatty acid profile of the milk. The antioxidant activity is due to the presence of protein peptides that have the ability to scavenge oxidative free radicals. Fermented milk has increased amounts of certain fatty acids, such as, linoleic, linolenic, and oleic acid. Linoleic and linolenic acid lowers cholesterol, guards against ischemic stroke, and has other attributes that reduces heart disease. Oleic acid also reduces cholesterol, in addition to lowering triacylglycerols, and the risk of coronary heart disease.

Summary

Milk is a natural and complex biological fluid, that not only provides nourishment for neonates, but serves as a nutritional food for adults as well. Milks nutritional value is practically idyllic in that it provides all of the essential amino acids that humans require, and carries functional bioactive ingredients that reduce the risk of developing disease.

The proteins, fatty acids, vitamins, and saccharides in milk strengthen the immune system against allergens and pathogens, by priming the adaptive immune system, modulating the composition of the microbiota, and strengthening overall intestinal function. The probiotic, anti-inflammatory, and antibacterial properties of milk  prevent the development of allergies and infection. Milk consumption not only reduces the risk of developing asthma and cow’s milk allergy when introduces during infancy, it also promotes the proper usage of insulin in adults and induces satiety, which wards against diabetes and obesity; risk factors for atherosclerosis (coronary artery disease).

While the processing and pasteurization of milk removes some of its functional proteins, enough of the beneficial bioactive components of milk remain. Furthermore, processing of milk, can be beneficial in other regards; fermented milk has therapeutic value and may be used as a natural antioxidant supplement. Unless you have cow’s milk allergy, milk intolerance, or lactose intolerance you should not suffer any allergic or gastrointestinal problems from drinking milk. Milk is a safe and nutritional food for human consumption.