Within the diabetes community, it often seems that protein is the forgotten macronutrient — getting less attention than the other two, carbohydrate and fat. Carbohydrate is scrutinized, of course, because of its effect on blood glucose levels, while fat is often viewed as a source of unwanted calories — or, depending on your perspective, as a good source of energy that doesn’t raise your blood glucose level. To the extent that protein gets any attention, it’s generally thought of as a good or neutral dietary component. But a prominent doctor is warning against consuming too much of it.
Last week, The New York Times published an opinion piece by Dean Ornish, MD, a clinical professor of medicine at the University of California, San Francisco. Ornish writes that high-protein animal foods such as meat and eggs are responsible for many of the ills plaguing Americans, including cardiovascular disease, cancer, and Type 2 diabetes. He cites a study published last year that found a 400% increase in deaths related to cancer or Type 2 diabetes among participants who got 20% or more of their calories from animal protein. This increased risk of disease and death, he writes, may be due to a number of effects animal protein has on the body. It increases inflammation and an insulin-like growth hormone known as IGF-1, and red meat and eggs have been shown to contain or produce substances that clog arteries and lead to increased inflammation and cancer risk.
Ornish maintains that the best diet is plant-based — filled with vegetables, fruits, whole grains, and legumes — and low in animal protein, refined carbohydrates, and both saturated and trans fats. Such a diet has been shown, he writes, to reverse the progression of even severe coronary artery disease, reducing episodes of chest pain by 91% and leading to 60% fewer cardiac events (such as heart attacks or strokes) in a five-year period. It may slow or reverse early-stage prostate cancer, and turn of certain disease-promoting genes. In addition, he writes, participants in one study lost 67% more body fat when fat calories were controlled than when carbohydrate intake was.
While Ornish’s emphasis on a whole-foods diet rich in fresh produce and whole grains isn’t opposed by many experts, his call to reduce animal protein is slightly more controversial. As we noted in a Diabetes Flashpoints post in 2010, there is some evidence that including more animal protein in the diet can help with weight loss — especially when it’s paired with carbohydrate-containing foods with a low glycemic index. This effect was seen in participants who consumed at least 25% of their calories from protein, a level Ornish considers potentially hazardous to health.
What’s your take on protein in the diet — do you pay attention to how much of it you consume? If you do, have you noticed that it has any effect on your blood glucose level? Have changes in protein consumption had any effect on your body weight? Have you found that reducing protein or animal fat in your diet makes it more difficult to stay full, or can plant foods be satisfying on their own? Leave a comment below!