New evidence that milk causes cancer? Don’t panic, this study should be interpreted like this

gossip

"Studies have shown that drinking milk increases the risk of two types of cancer. Don't drink milk anymore!"

There is news online saying that research shows that drinking milk increases the risk of liver cancer and breast cancer. Many netizens are panicked and even dare not drink milk or consume dairy products anymore.

Rumor Analysis

This statement circulating on the Internet is not rigorous.

Everyday food often only has a correlation with cancer risk. This type of research is just an exploration by researchers and should not be used directly as the basis for our daily consumption. Dairy products are still recommended as high-quality foods for "regular intake" in the dietary guidelines.

In the past two days, there has been a trending search on Weibo: "Frequent drinking of milk may increase the risk of these two cancers." This statement is very scary. What is going on? Can we still drink milk?

This claim is based on a study published in 2022. In fact, it was a hot topic in the media at that time, but it soon passed. I don't know why it was brought up again in the past two days, and it was summarized into such a scary topic.

The study tracked 510,000 adults in 10 different regions of China using data from national cancer and death registries and health insurance records. At the start, none of the participants had cancer. They were divided into three groups: frequent dairy consumers (at least once a week), monthly dairy consumers, and those who never or rarely consumed dairy products.

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Over the next 11 years, researchers determined the number of newly diagnosed cancers and investigated the dietary habits of these adults. The results showed that people who regularly consumed dairy products had an overall 9% increased risk of cancer. Specifically, "for every 50 grams of dairy products consumed per day, the risk of liver cancer and breast cancer increased by 12% and 17%, respectively." This was a study conducted by researchers from a well-known university, and there was nothing wrong with the data source. As a result, such data and results scared many people.

When the paper came out two years ago, many people asked about this. The author gave a simple and rough answer: treat this as a scientific research "game" and watch the scientists "play" it. There is no need to care about it yourself. Just eat and drink as usual.

Why do I say so?

In fact, the statement that "milk causes cancer" has long been around in foreign countries. The dairy industry, dairy competing industries, and research funded/led by "neutral organizations" have conducted various studies and discussions on this issue, but it is still a mess. Dairy products are still recommended as high-quality foods for "regular intake" in the dietary guidelines.

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It's just that those studies were conducted on Westerners, and there were almost no studies on the Chinese population. This study, which involved China's top academic institutions, was just a "repetition" of those studies on the Chinese population. Judging from the results, they were similar to those conducted on Westerners.

There is one big difference between food nutrition research and research in other fields: for the same food, there are often both "positive" and "negative" studies. If you see a study and do not seriously understand its content and limitations, but pick out a few sentences to "interpret", "deduce" or "use your imagination", you will "fly rumors and conspiracies together".

For the general public, to understand whether a food should be eaten, it is enough to look at the dietary guidelines - as far as milk is concerned, the latest version of the Dietary Guidelines for Chinese Residents recommends "300-500 ml of milk or corresponding dairy products per day."

Remember this conclusion, and just take a look at the other "latest studies" and don't take them seriously - you have to believe that if these "latest studies" you have seen really reach the strength of evidence for "recommended dietary changes", the National Health and Health Institute would issue an emergency notice , rather than the mass media/self-media in your circle of friends calling on "forward to your loved ones."

Back to the study itself, the researchers also discussed it and believed that "these results do not prove a causal relationship and further research is needed to verify these findings." They just emphasized that the significance of this study is that it "provides a comprehensive basis for investigating the relationship between dairy products and cancer risk in the Chinese population and provides directions for future research."

In fact, this is a "high EQ expression" of "don't take this result too seriously". In the past few decades, a large number of research papers in the field of food health have said this in the discussion section. After several years, there is no "future research" - just like "and then there is nothing else".

Looking in the mirror of rumors

Let's take breast cancer as an example. According to the "Guidelines for Screening, Early Diagnosis and Early Treatment of Breast Cancer in Chinese Women", the incidence of breast cancer in Chinese women in 2020 is 59.0/100,000. If the incidence increases by 17%, it is equivalent to an increase of 1 person in every 10,000 people. Are you not so worried after reading this? Many studies are used by professionals to examine risk factors from a macro perspective. For us individuals, the actual increased risk is actually far less than we think. Let's still follow the dietary guidelines and don't scare ourselves.

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Source: Yun Wuxin, PhD in Food Engineering, Science Writer

Review丨Zhang Yu, Researcher, Chinese Center for Disease Control and Prevention, Doctor of Medicine