Cow's milk consumption and risk of disease

Abstract

Milk and dairy products are important components of the human diet. This has been true since the beginning of domestication of lactating animals. However, milk of any species is geared towards the growth and development of its own offspring. Thus, the role of milk and dairy products in human nutrition has been increasingly discussed in recent years. To the best of our knowledge, problems such as lactose intolerance, protein allergies and an increased risk of cancer can occur when consuming cow’s milk. Around 70% of the world's total population is lactose intolerant, while 20% of adults in Europe are lactose intolerant. In the small intestine, lactose is hydrolytically split into glucose and galactose by the enzyme lactase located in the mucous membrane cells. After infancy, lactase activity decreases as the ability to synthesize lactase is lost. As a result, adults can no longer tolerate large amounts of lactose, and many develop diarrhea and uncomfortable painful symptoms such as gas, cramps, and a bloated stomach. Since lactase activity is limited in the case of hereditary lactose intolerance, people can easily tolerate milk without lactose. Another aspect is that between 2-5% of children are allergic to cow's milk. The allergy is less common in adulthood. Most allergic reactions affect the skin, gastrointestinal tract, and respiratory system, and severe anaphylaxis can occur. A therapeutic approach related to the causes of this multi-organ disease does not yet exist. A possible approach to reducing protein allergens is to block IgE-binding epitopes in patients. The most effective treatment is an elimination diet and the use of appropriate substitution formulas. Camel milk may replace cow's milk in the event of intolerance. Furthermore, many studies have showed that people with a higher cow’s milk intake had slightly increased cancer and all-cause mortality rates. 
 In conclusion, it has not been clarified what exactly constitutes the harmful or health-promoting effects of cow's milk. Cow's milk is so rich in ingredients that both effects are conceivable. Due to the central importance of milk and dairy products for human nutrition, there is still great scientific interest in expanding knowledge concerning the ingredients and their nutritional and physiological effects.