Milk - elixir of life or poison in a glass?

Dr. Andrea Bannert has been with since 2013. The doctor of biology and medicine editor initially carried out research in microbiology and is the team's expert on the tiny things: bacteria, viruses, molecules and genes. She also works as a freelancer for Bayerischer Rundfunk and various science magazines and writes fantasy novels and children's stories.

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Headlines on the subject of milk can make one fearful: “A glass of milk can be fatal” or “Milk promotes cancer”. Is that true? A fact check.

In the past, milk “perked up tired men”. A chubby boy advertised the "extra portion of milk" on the chocolate. If Grandma put a glass of milk in front of her grandchildren - it was good for the bones. Anyone who researches milk on the Internet today, however, grabs the horror: headlines such as “A glass of milk can be fatal”, “Milk leads to osteoporosis” or “Six good arguments to avoid milk”.

Opponents of milk associate the white drink with common diseases such as cancer, type 2 diabetes or strokes and heart attacks. But what do the scientific facts say? Is it really better to avoid milk, cheese, yoghurt and the like?

The Competence Center for Nutrition, KErn for short, was looking for a well-founded answer to this question. The nutritionists have evaluated and summarized almost 400 scientific studies on the subject of milk.

Question 1: cancer from milk?

Probably the greatest horror is the idea that milk can cause cancer. There are large studies that have examined this, especially for colon cancer, breast cancer and prostate cancer. For example, these cancers were examined more closely as part of the EPIC study, which collected data from a total of 500,000 participants in Western Europe.

Overall, these studies show that neither the risk of colon cancer nor the risk of breast cancer increases through the consumption of milk and dairy products. On the contrary, some studies even suggest that milk has a protective effect against these two types of cancer.

Scientists are not yet able to explain exactly why milk can protect against cancer. They suspect that a number of milk components could be involved in the defense against cancer. First and foremost the calcium. Because the mineral activates the programmed cell death, the so-called apoptosis. This is a natural protective mechanism that ensures that degenerated cells die instead of growing into tumors. The EPIC study comes to the conclusion that a daily calcium intake of 300 milligrams reduces the risk of colon cancer. To do this, you have to consume 150 milliliters of milk, 200 grams of yogurt or 30 grams of hard cheese.

Other anti-cancer substances in milk are possibly the polyunsaturated fatty acids. They stop inflammatory processes. Milk proteins, like casein peptides, also promote defense mechanisms. According to the Nutrition Report 2012, a glass of milk (200 milliliters) a day is enough to achieve a measurable positive effect.

Question 2: Are Men at Risk?

With prostate cancer, however, the protective effect fails. Some research suggests that a lot of milk, more than a liter per day, could slightly increase the risk of the disease. Depending on the study, by seven to 14 percent. The effect of skimmed milk seems to be higher than that of whole milk. Paradoxically, this phenomenon may also be due to the calcium in milk. Because researchers at the Wake Forest University of Medicine at the University of Wisconsin showed in a study that men with a high level of calcium in their blood were three times more likely to develop prostate cancer.

"Men who are closely related to prostate cancer should not exceed the recommendations of the German Nutrition Society of around 300 grams of milk per day," advises Professor Bernhard Watzl, Director of the Max Rubner Institute, the Federal Research Institute for Nutrition and Food participated in the study.

Question 3: Does milk tenderize the bones?

One of the most important positive properties that is ascribed to milk: It makes you big and strong. And that applies mainly to the bones. But is that also true? Critical voices claim that those who drink a lot of milk are more likely to develop osteoporosis or break something.

In fact, individual studies show that in the western industrialized countries, where a lot of milk and dairy products are consumed, more people develop osteoporosis. Probably other risk factors play a role here, because people in these countries exercise less and consume more alcohol and cigarettes.

In addition: As couch potatoes, you get less sunlight and thus produce less vitamin D, which plays an important role in bone stability. The scientists were actually unable to establish a clear connection between milk consumption and the risk of osteoporosis or fracture.

The fact is, if you drink a lot of milk, you can increase your bone density. This is especially true for children, adolescents and young adults. From the age of 30 to 35, the bone density then begins to decrease again continuously. Anyone who has stabilized their skeleton by then has made plans for old age, if not enough. Because many other factors can accelerate bone loss again later.

Question 4: Does milk clog the airways and intestines?

Opponents of milk also warn against mucilage from the white drink. Especially in asthma patients, this could worsen the symptoms. Traditional Chinese medicine believes that milk proteins are deposited on the intestinal villi and thus affect the absorption of nutrients. "These statements are not scientifically tenable," write the KErn experts.

But where does this prejudice come from? Milk is chemically nothing more than an oil-in-water emulsion, which is stabilized by proteins. If it comes into contact with the saliva in the mouth, some proteins may flocculate. This increases the viscosity of the saliva. The KErn authors believe that this could be mistakenly confused with increased mucus production.

Question 5: Milk allergy trap?

Many also avoid dairy products out of fear of allergies. "The allergy to cow's milk should not be confused with the lactose intolerance," says Watzl. A real allergy to cow's milk proteins, which leads to an excessive reaction of the immune system, is rather rare. 0.5 to seven percent of children and 0.7 to 1.2 percent of adults are affected.

“In contrast to this, lactose intolerance, i.e. lactose intolerance, is a harmless intolerance to milk sugar,” explains Watzl. It occurs in 10 to 15 percent of adults. Small amounts of lactose are usually tolerated anyway. Cured cheese can be eaten by those affected, for example, because it contains only small amounts of lactose.

Question 6: Where does the damage to the image come from?

The question that remains is how the milk from the white vest got a bad image. One reason for this is undoubtedly the inconsistent study situation - which not only affects milk, but also other foods. On the one hand, this is due to the fact that milk, fish or coffee are complex chemical structures that, unlike drugs, never have exactly the same composition. In addition, the data is mostly based on rough estimates made by the test persons themselves, how much of what they ate - another source of error.

And unlike drug studies, where the participants are under constant clinical observation, food studies can be falsified by many other factors that are easily overlooked. You already have a colorful hodgepodge of contradicting results. Only large overview studies then bring clarity - as happened here.

On the other hand, there is the tendency of people to create legends: “Behind the mistrust of milk there are certain ideologies and very subjective, individual assessments,” Watzl suspects.In the age of the Internet, they spread very quickly.

Conclusion: acquittal for the milk

There are obviously no scientifically proven data for the risk of milk consumption - not even for ideas that link milk with cardiovascular risk or diabetes. Clear recommendations for milk still exist in a quarter of the world's countries.

On average, we cover half of our calcium requirements with milk and dairy products. In the case of vitamins B2 and B12, it is still a good quarter. And then there are also zinc and iodine in the cow product. So Grandma was right: milk is obviously one thing above all else: pretty healthy.

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