In this study from France, 67,581 middle-aged women (40-65) were followed for 10 years, while their diet and disease status in relation to inflammatory bowel disease (IBD) were recorded regularly. (IBD includes Crohn’s disease and ulcerative colitis in which intestines and the colon become inflamed.)
This is what they found.
High total protein intake, specifically animal protein, was associated with a significantly increased risk of IBD, (up to 3 times the risk for highest meat and total protein consumption). Among sources of animal protein, high consumption of meat or fish but not of eggs or dairy products was associated with IBD risk.
Although this was a prospective trial looking forward in time, and it only investigated a distinct population group, it has some relevance to other more established studies that show increased risks of colon cancer in high red and processed meat diets. IBD is an established risk factor for colorectal cancer.
The take-home message here — as I’ve described elsewhere – is that high-meat diets, especially red meat, may not be consistent with healthy eating, and that high-protein diets in general, although somewhat popular for weight loss and other goals, should be constructed with careful attention to the protein constituents — vegetable and perhaps dairy protein being the best selections for the additional protein.