How Cow’s Milk Increases Breast Cancer Risk

When it comes to breast cancer, soy milk is generally warned against. However, one study showed that soy milk is not a problem when it comes to breast cancer, but cow’s milk is. Just one cup a day increases the risk of breast cancer by 50 percent – even though the German Society for Nutrition recommends a cup of cow’s milk a day.

Risk of breast cancer increases when drinking cow’s milk

According to a February 2020 study by Loma Linda University in California, the risk of breast cancer increases significantly when drinking cow’s milk.

Every eighth woman gets breast cancer, at least in industrialized nations. Risk factors include Alcohol, physical inactivity, and obesity. But some foods can also affect the risk of breast cancer.

For example, tomatoes, pomegranates, ginger, flaxseed, oolong tea, and mushrooms as well as onions and garlic protect against breast cancer. On the other hand, sugar and sausage are unfavorable.

Why soy milk does NOT increase breast cancer risk

So far, there has been no certainty about soy and dairy products. A study was published in 2017, according to cheese increases the risk of breast cancer, while soy critics are of the opinion that it is soy in particular that has an enormous carcinogenic effect.

It is said that a certain isoflavone in soy (genistein) activates the estrogen receptors on the cells and also has an estrogen-like effect. Since estrogen is considered to be carcinogenic and genistein had a growth-promoting effect on human breast cancer cells in cell experiments, the suspicion is that soy products are not recommended if you have breast cancer or want preventively optimal nutrition.

However, as early as 2010, researchers at Georgetown University in Washington wrote in the Journal of Nutrition that soy is more likely to reduce the risk of breast cancer, especially if you start eating soy at an early age). Further studies in the following years were able to confirm this connection, which we wrote about in our article Soy protects against breast cancer.

In 2015, the explanation was added: soy products (tofu, tempeh, soy milk, etc.) have a protective effect in terms of breast cancer. If, on the other hand, the isoflavones are isolated from soybeans and taken in capsule form as a dietary supplement, these highly concentrated and isolated substances seem to increase the risk of breast cancer – according to scientists at the time in the specialist magazine Molecular Nutrition & Food Research.

2020 study: Soy milk does not affect breast cancer risk

For the above-mentioned epidemiological study from February 2020, a research team from Loma Linda University in California again examined the connections between cow’s milk or soy consumption and the risk of breast cancer in almost 53,000 women. The women were breast cancer-free at the start of the nearly 8-year study. Over the course of the study, there were just over 1,000 cases of breast cancer.

First of all, no connection with the consumption of soy products could be determined. Obviously, soy could neither reduce nor increase the risk of breast cancer.

Cow’s milk increases breast cancer risk by up to 80 percent

In this study, however, the consumption of cow’s milk could increase the risk of breast cancer – by up to 80 percent, depending on the amount consumed. Women who drank no milk or only a little cow’s milk had a significantly lower risk of developing breast cancer than women who consumed a lot of dairy products. It was irrelevant whether it was low-fat milk or full-fat milk.

Study author Gary E. Fraser said that with the study there is now quite strong evidence that cow’s milk is a causative factor in breast cancer. “Just a quarter to a third cup of cow’s milk a day can increase the risk of breast cancer by 30 percent,” Fraser said. “Anyone who drinks up to one cup of cow’s milk a day has a 50 percent increased risk, and anyone who drinks two or even three cups of milk a day has a 70 to 80 percent increased risk of developing breast cancer.

Nutrition Society Recommendations Increase Your Risk Of Breast Cancer!

With nutritional societies currently recommending three cups of milk a day in the US, this recommendation should be taken with caution given the new findings from Fraser’s study. In Germany, the German Society for Nutrition recommends a cup of cow’s milk (250 ml milk (and 50-60 g cheese)) daily. So if you follow the recommendations of the DGE, you increase your risk of breast cancer.

Good idea: exchange cow’s milk for soy milk

According to Fraser, anyone who wants to reduce their breast cancer and has been drinking cow’s milk should swap the cow’s milk for soy milk. This was also indicated by the results of the AHS-2 (Adventist Health Study-2), a study with a total of about 96,000 participants in which vegan women had a lower risk of breast cancer than normal eaters. However, vegetarians had the same risk of breast cancer as the participants who ate normally.

High hormone levels in milk could be the problem

Fraser suspects the high hormone content in the milk as a possible reason. After all, 75 percent of all dairy cows are always pregnant. Just like other animal products, dairy products also increase the level of the so-called IGF-1, a growth hormone that is normally responsible for healing and regeneration processes but can also promote cancer growth.

“Of course, from a nutritional point of view, cow’s milk also has some positive properties,” explains Fraser, “but these should be weighed against the possible negative effects.”

When evaluating the study, factors such as a family history of breast cancer, alcohol consumption, physical activity, medication (e.g. hormone preparations) that were taken, preventive medical check-ups that were used, and their results, etc. were also taken into account.

If you thought of a number of the disadvantages of soy milk circulating online when you heard the tip about swapping cow’s milk for soy milk, read our article on the usual criticism of soy.

Raw milk and the risk of breast cancer

Some readers asked whether the above also applies to raw milk. Our answer to this question was: No corresponding distinction was made in said study. However, we assume that this is the regular pasteurized and homogenized milk consumed by most people. Since there is also no study on the influence of raw milk alone on the risk of breast cancer, no statement can be made on the subject of raw milk and the risk of breast cancer.

Should such a study be published, we will of course report immediately. However, it should never be forgotten that raw milk also contains the corresponding growth-promoting hormones, possibly in higher quantities than heat-treated milk, since heat treatment can reduce hormones.

Sheep or goat milk and the risk of breast cancer

Likewise, readers asked whether it would not be best to swap cow’s milk for goat’s or sheep’s milk in order to avoid the increased risk of breast cancer from cow’s milk without having to do without milk and dairy products altogether.

In said study, however, only a possible connection with the consumption of cow’s milk was checked. Other animal milks and its influences have not been studied.

However, the cancer-promoting effect of milk is probably a consequence of the naturally contained growth-promoting hormones that are contained in all animal milk, since without them the goal of breast milk could not be achieved. The goal is: The baby should grow! Since baby animals, in particular, grow particularly quickly (compared to human children), animal milk always contains large amounts of growth hormones – whether from cows, sheep, goats, dogs, or other mammals.

However, the estrogen content is said to be higher in cow’s milk than in goat’s milk, which is because cows are usually pregnant again when they are milked. Goats, on the other hand, have a longer non-pregnant period per year, not least because the gestation period is much shorter than that of cows. Unfortunately, we do not have any other comparisons (with other types of milk).

Conclusion: Sheep’s and goat’s milk also contain growth hormones, but possibly less estrogen/pregnancy hormones. The risk could therefore be lower with these types of milk. Unfortunately, we are not aware of any comparative study.

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