Recently, more and more conflicting information has appeared about the benefits of milk for the human body. Some consider milk a very healthy drink for health, while others, on the contrary, are ardent opponents of milk, claiming that milk can cause many diseases. In this article we will consider only scientifically proven facts about milk, and its role for the human body.
Milk is a very nutritious fluid that forms in the udder of a cow, and is designed to feed a newborn calf so that it quickly and well develops and gains weight.
A wide variety of food products is made from cow’s milk: cheese, cream, butter, cottage cheese, yogurt. These products are called dairy products, and they are included in the diet of many people.
The nutritional composition of milk is very complex and contains almost all known nutrients needed by the human body. We also note that there are two types of protein in milk – milk A1 and A2 . The second type is now recognized as more useful than the first.
Nutritional Information of Milk
The following is information on the nutrients in whole milk 3.25% fat per 100 grams ( 1 ).
Calories : 61 kcal
Water : 88%
Protein : 3.2 gr.
Carbohydrates : 4.8 gr.
Sugar : 5.1 g
Fiber : 0 gr.
Fat : 3.3 gr.
Saturated Fat : 1.87 gr.
Monounsaturated : 0.81 gr.
Polyunsaturated : 0.2 gr.
Omega-3 fatty acids : 0.08 g.
Omega-6 fatty acids: 0.12 g.
Trans Fat : ~
Keep in mind that many dairy products are enriched with vitamins, including vitamins D and A.
Milk is a rich source of protein (1). It contains approximately 1 gram. protein in every 30 grams. or 7.7 gr. in each cup (250 gr.).
Depending on their solubility in water, proteins in milk are divided into two groups: insoluble milk proteins or casein, and soluble proteins or whey proteins.
Both casein and whey proteins are excellent quality proteins. They are well absorbed by the human body and contain a large number of essential amino acids.
The benefits of milk for the human body are manifested in the content of high-quality protein in milk, which can be divided into two categories: casein and whey proteins.
Casein forms up to 80% of the proteins in milk. Casein is actually a family of different proteins, and the most common is alpha casein.
One of the main properties of casein is its ability to transfer calcium and phosphorus minerals and increase their absorption by the body ( 2 ).
There are also studies proving that casein is able to lower blood pressure ( 3 ).
Most proteins in milk are classified as casein, which has several advantages for the human body, namely it helps to absorb calcium and phosphorus, while being their source.
Whey is another family of proteins that account for 20% of all protein in milk. Whey protein is soluble in water and has various beneficial properties.
Serum is especially rich in isoleucine, leucine and valine, a branched-chain amino acid group (BCAA).
Scientists associate whey proteins in milk with many beneficial effects on the human body. Like casein, whey protein helps lower blood pressure ( 4 ). In addition, this type of protein is able to improve mood during periods of stressful situations ( 5 ).
Whey protein intake is great for muscle growth and maintenance. That is why whey protein supplements are so popular among professional athletes and bodybuilders.
Whey proteins are one of the two main types of proteins in milk. In addition to being good for growing and maintaining muscle mass, they can also lower blood pressure and improve mood.
Whole fresh milk contains about 4% fat.
In many countries, milk marketing is based on its% fat content. In the US, whole milk makes up 3.25% fat, while normalized milk makes up 2% fat and skim milk at 1%. In Russia, whole fat milk may have a fat content of 3.5% -4.5%, normalized – 2.5%, skim – 1%.
Milk fat is considered one of the most comprehensively formulated natural fats. Its content includes more than 400 types of fatty acids ( 6 ).
Whole milk is excessively rich in saturated fats, which occupy about 70% of all fatty acids in milk. Monounsaturated fats take the second place – they occupy about 28% of the total fat content. And the remaining 2% fat in milk is polyunsaturated fat.
Summary : The
fat content of fresh milk is usually 4%, but the fat content in processed milk can vary from 1% to 4.5% and depends on the type of processing. Milk fat is mainly composed of saturated fats.
Trans fats are also found in dairy products. But unlike the unhealthy trans fats found in processed foods, milk trans fats, also called natural trans fats, are generally considered beneficial to the human body.
The small amount of trans fats found in milk is two acids: vaccenic acid and conjugated linoleic acid or CLA ( 7 ). Linoleic acid has attracted significant attention from scientists due to various health benefits ( 8 ). However, large doses of linoleic acid, taken in the form of a dietary supplement, can have a harmful effect on metabolism ( 9 ).
Milk contains a small amount of natural trans fats. Conjugated linoleic acid (CLA) is the most studied type of trans fat and has several health benefits.
Carbohydrates are present in small quantities in milk and are milk sugar. It is also called lactose. Milk sugar occupies only 5% of the mass of milk.
In the digestive system, lactose normally breaks down into galactose and glucose. Then they are absorbed into the bloodstream. Once in the liver, galactose is also converted to glucose.
Some people lack an enzyme called lactase, which is essential for breaking down lactose. This condition is called lactose intolerance or lactase deficiency. Sometimes this condition normally occurs in infants and disappears with age.
Carbohydrates make up about 5% of milk, most of which are lactose (milk sugar).
Vitamins and Minerals
Milk is extremely rich in vitamins and minerals. Their number is so large that it fully covers the need for a newborn calf in nutrients for proper growth and development.
But this also applies to humans. The nutrient profile in milk is impressive and can also satisfy the needs of the human body, being a truly saturated and useful product for maintaining the body’s vital functions.
The following vitamins and minerals are found in especially large quantities in milk:
Vitamin B12 : Among food sources, this vitamin can only be found in animal products. Milk contains 22% of the daily intake of vitamin B12 per 100 g.
Calcium : milk is not only one of the best dietary sources of calcium, but also the calcium contained in milk is easily absorbed by the human body ( 10 ).
Riboflavin : a vitamin B group, namely vitamin B2. Participates in carbohydrate metabolism and helps fight stress. It is found in large quantities in dairy products, which are often the main source of this vitamin for many people.
Phosphorus: a mineral that is vital not only for the health of teeth and bones, but also as a participant in many chemical processes in the body. Milk is a good source of phosphorus.
Vitamin D fortified milk
Fortification, also called fortification, is the process of adding minerals or vitamins to foods.
As a public health strategy, fortification of dairy products with vitamin D is common and even mandatory in some countries.
In the United States, one cup of vitamin D-fortified milk (250 grams) may contain 65% of the recommended daily allowance for vitamin D ( 11 ). In Russia, some manufacturers also enrich milk with vitamin D, however, this practice is not yet so common.
Milk is a terrific source of many vitamins and minerals, including vitamin B12, calcium, riboflavin, and phosphorus. It is often enriched with other vitamins, especially vitamin D.
Perhaps the most controversial point when reading various information about milk is the supposedly negative effect of milk hormones on the human body.
Let’s study the facts:
More than 50 different hormones are naturally present in cow’s milk. These hormones are important for the development of a newborn calf ( 12 ).
With the exception of insulin-like growth factor-1 (IGF-1), cow’s milk hormones have no known effects on the human body.
IGF-1 is also found in human breast milk and is the only hormone that is absorbed by the human body from cow’s milk. It participates in the process of cell growth and regeneration and is more beneficial for the human body than harmful ( 13 ).
Growth hormone is another hormone that is found in milk in small quantities. It shows biological activity only in the body of the calf and has absolutely no effect on the human body.
Milk contains a large number of hormones that contribute to the development of a newborn calf. Only one milk hormone, insulin-like growth factor 1 (IGF-1), can affect people’s health.
Bone Health and Osteoporosis
Osteoporosis is a painful condition in the body in which bone density decreases, which causes an increased risk of bone fractures among the elderly.
One of the functions of cow’s milk is to promote bone growth and development in a young calf. As already noted, the nutrients and nutrients of cow’s milk can also work well on the human body. It has been proven that the use of milk helps to strengthen bone mass and higher bone density in humans ( 14 ). Scientists explain this beneficial property of milk with a high content of calcium and protein ( 15 ).
Being a rich source of calcium, milk can increase bone mineral density, reducing the risk of osteoporosis.
Other beneficial properties of milk for the human body
Milk is one of the most nutritious foods that basically exist on the planet. It has been widely studied and has several important proven health benefits.
Hypertension, which manifests itself in periodically rising to abnormal levels of blood pressure, is a major risk factor for the development of cardiovascular diseases.
Dairy products have been proven to reduce the risk of developing hypertension ( 16 ). It is believed that this is due to the unique combination of calcium, potassium and magnesium found in milk ( 17 ).
It is suggested that other elements in milk, such as peptides produced by the digestion of casein, the main class of protein in milk, can also contribute to pressure reduction ( 18 ).
Milk and dairy products help lower blood pressure.
Lactose, also called milk sugar, is the main carbohydrate found in milk. In the digestive system, it is divided into subunits, glucose and galactose. However, this does not occur in all people.
An enzyme called lactase is needed to break down lactose. In some people, the body does not contain enough of this enzyme, which does not adequately digest milk sugar. This condition is called lactase deficiency or lactose intolerance.
It is estimated that about 75% of the world’s population has lactose intolerance ( 19 ). However, the proportion varies greatly depending on the genotype. For example, African Americans and people with dark skin who live in Africa and South America are more likely to suffer from lactase deficiency. The proportion of people with lactose intolerance in European countries, the USA and Russia is much lower.
In people with lactase deficiency – lactose is not completely absorbed by the body, and part (or most) of it passes into the colon. And the colon bacteria begin the fermentation process, which leads to the formation of short-chain fatty acids and gas, such as methane and carbon dioxide.
Lactose intolerance is associated with many unpleasant symptoms, such as gas, bloating, stomach cramps, diarrhea, nausea and vomiting.
Many people have intolerance to milk sugar (lactose). The main symptoms are bloating, flatulence and diarrhea.
Other side effects of milk
The health effects of drinking milk are complex.
Some components of milk are very beneficial, but others can have an adverse effect.
Cow’s milk protein allergy (BKM)
Milk allergy is rare in adults, but is more common in young children ( 20 ).
Most often, allergic symptoms are caused by cow’s milk protein, namely whey proteins called alpha-lactoglobulin and beta-lactoglobulin, but there is also an allergy to casein ( 21 ).
Allergies to milk can occur with the following main symptoms: skin rashes, breathing problems and swelling, vomiting, diarrhea, and blood in the stool ( 22 ).
In many children, allergies to cow’s milk protein disappear with age.
Drinking milk can cause acne ( 23 ).
Acne (or acne) is a common skin disease characterized by rashes on the face, chest, and back.
Milk and cancer
Many studies have raised the question of a causal relationship between dairy consumption and cancer risk. In general, the data are mixed, and very few conclusions can be drawn from them.
As a general recommendation, excessive human consumption of milk should be avoided. If you want milk to benefit the body, use it sparingly.
In addition to the fact that milk is an allergen for some people, milk also has several adverse effects, such as an increased risk of acne and prostate cancer.
Milk Processing Methods
Almost all milk that can be bought on the shelves in stores is processed in some way. This is done in order to increase the safety of milk consumption and extend the shelf life of dairy products.
Pasteurization is the process of heating milk to 60-80 degrees Celsius to destroy potentially harmful bacteria that are sometimes found in raw milk ( 30 ).
High temperatures destroy beneficial as well as harmful bacteria, yeast and mold. However, pasteurization does not make milk sterile. Therefore, it must be quickly cooled after heating in order to preserve the surviving bacteria.
Pasteurization leads to a slight loss of vitamins due to their sensitivity to high temperatures, but does not significantly affect the nutritional value ( 31 ).
Milk fat consists of countless globules of various sizes. In raw milk, these fat globules tend to stick together and float on the surface of the milk.
Homogenization is the process of breaking down these fat globules into smaller units. This is done by heating the milk and pumping it through narrow pipes under high pressure.
The goal of homogenization is to increase the shelf life of milk and give it a richer taste and a whiter color.
Most dairy products are made from homogenized milk. An exception is cheese, which is usually made from raw milk.
Homogenization does not adversely affect product quality ( 32 ).
To increase shelf life and safety, commercial milk is pasteurized and homogenized.
Raw milk or pasteurized milk: which is better?
Raw milk is a term used for milk that is not pasteurized or homogenized.
Pasteurization is the process of heating milk to increase shelf life and minimize the risk of disease from harmful microorganisms that may be present in raw milk.
Heating leads to a slight decrease in the amount of vitamins, but this loss is negligible from a health point of view ( 33 ).
Homogenization, which is the process of breaking down fat globules in milk into smaller units, has no known adverse health effects ( 34 ).
Raw milk consumption is associated with a reduced risk of asthma in children, eczema, and allergies ( 35 ). However, studies on this issue were small and inconclusive.
Although raw milk is more “natural” than processed milk, its use is more risky.
In healthy cows, milk does not contain bacteria. During the milking, transportation or storage process, the milk is infected by bacteria either from the cow itself or from the environment. Most of these bacteria are not harmful, and many of them are even beneficial, but sometimes milk gets infected by bacteria that can cause the disease. Although the risk of consuming raw milk is very small, a single milk infection can have serious consequences.
- Milk is one of the most nutrient-rich drinks in the world. It is not only rich in high-quality protein, but also an excellent source of vitamins and minerals such as calcium, vitamin B12 and riboflavin.
- For this reason, milk can reduce the risk of osteoporosis and lower blood pressure.
- On the other hand, some people are allergic to milk proteins or intolerant of milk sugar (lactose). Some studies have linked high milk intake to an increased risk of developing prostate cancer, but the evidence for these experiments is weak.
- Nevertheless, it can be concluded that moderate consumption of milk will benefit the human body, while excessive consumption should be avoided.