Doctors Against Dairy: Cheese Linked to Breast Cancer Risk

Petition signed by 12,000 American doctors calls on FDA to require warning labels on cheeses

Yulia Davidovich / Shutterstock

In one of the more startling developments in food science, 12,000 doctors in the United States are petitioning for warning labels on cheese. “Dairy cheese contains reproductive hormones that may increase breast cancer mortality risk,” they warned.

What, is cheddar the new cigarette? No. Casein and estrogen are not nicotine and nobody’s about to blotch Brie with a label saying “Eating this kills.” 

It is not suggested that eating cheese causes breast cancer. It isn’t even categorically proven that eating cheese really is associated with higher breast cancer rates, or that eating cheese causes higher mortality rates among women who already developed breast cancer. There are a lot of studies but the methodology is hardly uniform or even necessarily reliable, and there are innumerable parameters, including some that may be overriding. Like smoking, or living in nuclear waste. Those are parameters that tend to outweigh other parameters.

But the associations found so far are compelling enough for the doctors to choose to speak up.

A woman’s risk of developing breast cancer is 12.8 percent, or one in eight, in the United States. For men, it’s 0.13 percent, or just over one in a hundred.

The rate of invasive breast cancer incidence is lower, the Health Ministry told Haaretz — in Israel, it’s is 92.2 per 100,000 among Jews, and 69.8 among Arabs (compared to 124 per 100,000 in America — all figures for 2016). The older the person, the higher the probability: in Israel, almost 80 percent of breast cancer patients are aged over 50, and around 5,000 breast cancer patients are detected each year. 

Certain individuals are at higher risk because of genetic factors, lifestyle factors or factors that nobody knows about yet — including, it seems, a predilection for high-fat fromage.

The citizen petition was organized by the Physicians Committee for Responsible Medicine.

Among the evidence: A 2017 study funded by the National Cancer Institute that identified a 53 percent increase in the probability of breast cancer development among women who ate “the most American, cheddar, and cream cheeses.”

Another study found that among women with breast cancer, eating cheese is associated with a higher mortality risk. In a nearly 12-year follow-up, women eating one or more servings of high-fat dairy products a day (which could mean whole milk) had 49 percent higher breast cancer mortality.

“High-fat dairy products, such as cheese, are associated with an increased risk for breast cancer,” concludes the PCRM.

Proving associations between food and morbidity is extremely difficult because of the overwhelming number of parameters involved. Take cheese. What is cheese, anyway? “Dairy foods are complex mixtures which include nutrients and non-nutrient substances that could potentially influence cancer etiology, including breast cancer,” explains a separate paper published in Current Developments in Nutrition.

Let's assume we can figure out what cheese is. If eating cheese really is associated with breast cancer, what component or components are responsible? We don’t know. If the culprit is the fat component, is there a safe level of fat in cheese? We don’t know. Does the risk outweigh the nutritional benefits of cheese to the lactose tolerant? What if the data is skewed by people lying about their cheese habit, or smoking, or diet in general, or their exposure to other carcinogens?

The culprit in cheese, if there is one, may be estrogenic hormones, though science never did understand exactly why a higher lifetime exposure to estrogen may be associated with breast cancer risk (which, again, does not mean the estrogen causes breast cancer).

Should we be eating cheese at all? Mammals wean their young, who after that turning point do not eat dairy and tend to lose their ability to produce lactase (the enzyme that digests milk and its products). But some studies do indicate that general dairy consumption — including, but not confined to high-fat — is good for us. Certainly it can be an advantage for vegetarians, if they can digest it.

In humans, the perpetuation of infantilism in the form of dairy consumption seems to have developed well after the domestication of the goat, sheep and cow some 11,000 years ago. The earliest-ever direct evidence of milk consumption was in, of all places, Britain — nowhere near where the animals were first husbanded, though whether the Neolithic farmers 6,000 years ago could actually digest the stuff or were stoic about the results of eating it is not clear. 

Last year, archaeologists identified the earliest-known hard cheese, in an ancient Egyptian tomb dated to around 1615 B.C.E. It had been made of a mix of milks from sheep, goat and African buffalo

Breast cancer, like all cancers, is enigmatic, and if there are risks they’re worth knowing about. Alcohol consumption is also associated with higher cancer risk, for instance, and yet again science isn’t sure why. Particulate smog is as well.

This doesn’t mean you have to forgo romantic wine and cheese smorgasbords by the fireside. What it means is: all things in moderation. Boring? Vary the cheese selection and add some vegetable sticks.