Douglas Kelly, MD
and Rebecca Wright, DO
The Paleolithic diet has received a lot of attention in the past few years. In fact, it was Google’s most searched for diet in 2013. But the diet is not without controversy, with equally forceful proponents and opponents—even within our hospital.
Both of us follow the Paleo diet, also known as the “caveman diet,” and believe it’s healthy and tasty. As doctors who treat cancer patients, we wanted to address the question of whether a Paleo eating plan can help prevent and treat cancer.
The Paleo diet is based on foods our ancestors would have eaten thousands of years ago during the hunter-gatherer era. Researchers have found that early humans ate the animals they hunted, nuts, seeds, berries and root vegetables.
The modern version of the diet consists of:
- Vegetables: whole, frozen, fermented and pickled
- Fruit: whole, frozen and rich in healthy fats (coconut, avocado and olives)
- Meat, fowl, fish, eggs and organ meats from natural sources
- Dairy from pastured cattle
- Nuts, seeds and their butters
- Dark chocolate
- Healthy oils: olive, coconut, butter and ghee
- Herbs, spices, salt and pepper, vinegar, broth and salsa
- Stevia and limited honey
- Water, mineral water, tea, coffee and limited alcohol
Looking at the diet in the context of cancer, it’s important to note that cancer is a disease of modern civilization and is not often seen in hunter-gather groups that still exist. Modern hunter-gatherers eat a Paleo-like diet and significantly fewer processed foods, they get more physical activity and sunshine, and they have less chronic stress.
Vegetables and fruits are the main sources of carbohydrates in the Paleo diet. The plan encourages you to eat as many vegetables as you can, even up to nine cups a day in the Wahls protocol. The body uses carbs to make glucose, or blood sugar.
The connection between sugar and cancer is long established, which is why it’s best to get your carbs from whole foods with natural sugars. In 1931, Dr. Otto Heinrich Warburg won a Nobel Prize for his research showing that cancer cells use glucose as their preferred fuel.
Cancer cells have special mechanisms to draw a lot of glucose from the blood. For a PET scan, radioactive sugar is injected into the body. Most tumors will pull in more glucose than the surrounding healthy areas, and the tumors will be seen to “glow” on the scan. Sugars and other carbs, especially from cereal grains and cows' milk, also can increase insulin levels and the insulin growth factor (IGF1), which stimulate tumor growth.
The Paleo diet may benefit people who want to prevent cancer and patients undergoing treatment because of less glucose in the blood, lower insulin levels, better insulin response, less inflammation and more cancer-fighting micronutrients.
Vegetables and fruit contain a variety of micronutrients and cancer-fighting substances such as trace minerals and antioxidants. Anyone following the Paleo diet should get their meat, fowl, fish, eggs and dairy from animals fed a natural diet, meaning wild animals or grass-fed and pastured animals that have room to roam.
The Paleo diet avoids most processed vegetable oils because they contain omega-6 oils, which are considered to be inflammatory and immune suppressive. But nuts and seeds are encouraged and have been shown to reduce the chance of developing certain cancers.
The Paleo diet may not be for everyone. If you’re considering it, we recommend you consult with your physician and a dietitian first. Learn more about what to eat during cancer treatment.