The study, which examined the effects of high protein intake in both humans and mice, identified the likely culprit being the increase in insulin-like growth factor 1 (IGF-1). IGF-1 is a known promoter of cancer cell growth and the consumption of meat and especially dairy products, stimulates its release in humans and animals. Protein from vegetable sources (beans, nuts, seeds etc) does not, however, cause the release of IGF-1.
This finding doesn’t surprise me at all. We’ve known about the cancer promoting properties of both meat and milk for along time. It is this increase in cancer risk that is largely driving the increase in risk of mortality. While high protein diets are an effective way to lose weight they are not more effective than a low GL diet, with moderate protein intake (up to 20% of calories and a maximum of 25% of calories for short-term use only) derived largely from fish and vegetable sources, and a low intake of meat and milk. This is what I have been advocating for over ten years precisely because of my concerns over the cancer-promoting properties of milk and meat. Many of these high protein diets recommend at least double this quantity of protein, mainly from meat, cheese and other dairy products. This is certainly bad news for health, even if it works for short-term weight loss. The California study found increased cancer risk above 20% of calories, but only in the age group of 50 to 65.
The link between high protein and cancer is strongest for dairy products in relation to cancer of the prostate, breast and colorectal cancer. The fact that these cancers are increasing, while others are decreasing, suggests that most advice for cancer prevention is missing something important. I am very confident that this now established link between meat and milk raising IGF-1 levels and thus promoting cancer, is the missing link in the rise of prostate and probably breast cancer. This is completely consistent with the scientific evidence.
Back in 2007 the World Cancer Research Foundation in 2007 reported that dairy products increase the likelihood or severity of prostate cancer. Earlier this year a study in the Journal of Nutrition confirmed that the more dairy a man consumes the greater is their risk of prostate cancer. Whole milk intake was associated with doubling the risk of progression from a prostate cancer diagnosis to death.
According to the National Cancer Institute (NCI) 19 out of 23 studies have shown a positive association between dairy intake and prostate cancer: ‘This is one of the most consistent dietary predictors for prostate cancer in the published literature … In these studies, men with the highest dairy intakes had approximately double the risk of total prostate cancer, and up to a fourfold increase in risk of metastatic or fatal prostate cancer relative to low consumers.’ Vegetarians have a lower prostate cancer risk and countries with the lowest dairy intake have the lowest rate of prostate cancer fatalities.
Similarly, a study this year in the Journal of the National Cancer Institute finds that high-fat dairy product intake is associated with higher breast cancer mortality, while low-fat dairy intake was not. While the link between overall dairy intake and breast cancer risk is not as strong as for prostate cancer, the advice to avoid dairy products if you have breast cancer or are at significant risk, still holds true, especially in regard to full-fat dairy products which have more oestrogens, another cancer cell growth promoter.
For more information about nutrition and cancer visit www.patrickholford.com/topic/cancer.