Protein Restriction Improves Health by Pamela A. Popper, Ph.D., N.D.
The most common question asked of anyone who adopts a plant-based diet is “Where do you get your protein?” People live in fear of protein deficiency, which is virtually impossible with a diet of any type that contains adequate calories. Even plant foods with the lowest protein content, such as potatoes at 8-9% protein, contain more protein than we need. Protein needs have been established at percentages as low as 2.5% of calories by the World Health Organization, and human breast milk, which fuels the most rapid growth of humans in their entire lifetime is only 6% protein. In fact, our problem is not that we can’t get enough protein, it’s that we’re eating too much, and a significant body of research shows this.
A group at Washington University in St. Louis under the direction of Luigi Fontana has been researching calorie restriction as a means for preventing disease and slowing aging. While the results so far have indicated that eating about 30% less calories daily does improve health and reduce the risk of disease, I have often commented that it may not be the calorie restriction but the change in the macronutrient makeup of the diet and the foods eliminated in the process of restricting calories that accounts for the positive effect. It is impossible to reduce calories by 30% while eating oils and high-protein foods like animal foods.
Fontana’s own data shows that this might be the case. IGF-1 is a protein that promotes growth in children. High IGF-1 levels in adults have been shown to increase the risk of developing several types of cancer, particularly breast and prostate cancer.
In 2008, one of Fontana’s studies showed that calorie restriction did not lower IGF-1 levels, but that protein restriction did. What is the easiest way to restrict protein consumption? Reduce or eliminate animal foods, since animal food is a very concentrated source of protein in the diet.
Fontana’s results are even more important when combined with T. Colin Campbell’s research results which showed that increased consumption of animal protein increased incidence of cancer in lab rats, and that differences in animal foods consumption caused an increase in the incidence of cancer and heart disease in the Chinese subjects in The China Project.
It is a lot easier to restrict protein consumption than to reduce calorie consumption by 30% for most people. I have looked that the daily diets of some of the calorie-restricted subjects and do not think I could make a commitment to be hungry all of the time, which would most certainly be the case.
Different researcher and research group, but same message – eating too much animal foods is hazardous to your health.
Fontana, L, Weiss, E, Villareal D, et al. “Long-term effects of calorie or protein restriction on serum IGF-1 and IGFBP-3 concentration in humans.” Aging Cell October 2008;7(5):681-687.
Audrey’s Note: If you want some help eating a plant-based diet, get in touch. We have Wellness 101 classes and cooking classes.