In the article in today’s email “The Paleo Diet Promotes Greater Vitality in Later Years” by Pedro Bastos he writes about the Okinawan Diet. He writes that they don’t eat potatoes but I understand that they eat lots of Sweet Potatoes.
Dr. Cordain’s Response:
Yes, probably they ate big amounts of sweet potatoes as some hunter-gatherers do in Kitava-Papua New Guinea. Our ancestors didn’t have an universal diet because it depended on climate, season, latitude, culture, etc. This means that the amount of carbohydrates they ate varied substantially. So, for instance in Kitava they eat a lot of carbohydrates and still have no obesity, so it seems as if some bioactive substances of neolithic foods are responsible for hormonal disruption rather than merely carbohydrate content.
However, there’s a big difference between potatoes and sweet potatoes. Potatoes are a good source of some known harmful substances namely saponins. They have the ability to increase intestinal permeability and hence increase the risk of autoimmune diseases (in genetically predisposed individuals), and induce low-grade chronic inflammation which is at the root of many chronic degenerative diseases. On the other hand, there’s some preliminary data suggesting that some bioactive substances, such as lectins and saponins, contained in potatoes, grains, legumes, etc. can bind hormonal receptors impairing their function. This could be the case of leptin receptor leading to leptin resistance and some metabolic disorders.
Potatoes are a very new food for humans, as they came from North America less than 600 years ago. On the other hand, it seems that sweet potatoes are part of the human diet since a long time ago.
Loren Cordain, Ph.D., Professor Emeritus