Hi Drs.,
Today I listened to a podcast featuring a German physician specializing on nutrition who said quite a few plausibel things but made one claim which I found concerning. She said that a “high consumption of animal proteins — with yogurt or quark for breakfast, turkey or salmon for lunch, and mozzarella in the evening — quadruples the risk of cancer in people between the ages of 50 and 65, according to a study. A figure comparable to smoking. This is because animal proteins stimulate tissue growth through the release of the growth hormone IGF-1. In contrast, protein from plant sources did not trigger this effect.”
I’ve read most of your content on nutrition, including your guide on protein, and I didn’t come across any mention of this particular claim. So my question is: are you familiar with this research (the author didn’t cite any sources), or do you know of other studies that contradict it?
Interestingly, she also stated that for individuals aged 65 and older, the situation shifts — animal protein is said to reduce mortality risk and help maintain muscle mass in older adults.
Thanks in advance!
Yes, we are very familiar with this research. Unfortunately, it does not appear the individual making the claims can say the same.
The observational data on protein consumption shows that most people eat a decent amount of protein, but that their dietary patterns are not very good, as measured by fiber intake, level of processing in foods consumed, sodium intake, saturated fat content, and total Calories.
People who tend to eat the most animal protein tend to eat less vegetable matter, and have a high intake of processed foods. This is why the relationship between increasing plant protein (vs. animal protein) tends to show improved health outcomes. When dietary fiber intake is also high however, high levels of animal protein appear to be consistent with equivalent health outcomes to plant-based diets.
If allowed to be snarky for a minute, the idea that a well-informed physician would publicly state eating yogurt quadruples the risk of “cancer” is insane to me. How does one say that without being like…hmmm, maybe I’m misunderstanding this?
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Thanks Jordan for the quick and comprehensive reply. I am glad I didn’t ditch my evening quark yesterday based on this misinformation 
It is kind of concerning that she has been invited as a medical expert to countless German tv shows over the past 10+ years. As she seems to be dermatologist she mainly talked and wrote about how to get brilliant skin up until recently when she also published a best selling book whose titel translates to something like “optimally nourished”.
It’s somewhat concerning that she has been invited as a medical expert on countless German TV shows over the past 10+ years. As a dermatologist, she primarily focused on how to achieve radiant skin—at least until recently, when she published a bestselling book titled something like ‘Optimally Nourished.’ Now, she’s all over German media sharing her insights on nutrition, which mostly seem reasonable—except for the concerning misinformation that consuming primarily animal protein increases cancer risk to a level comparable with smoking.
Perhaps I should try to make her aware of her misinterpretation of the research, as it’s likely not in her interest to spread misinformation. On the other hand, I doubt she would take me seriously, given my lack of formal expertise.
I agree that it is unlikely she has actual expertise in the field as a dermatologist (or really any doctor for that matter). It is also unlikely that telling her she’s incorrect would be well-received.