Diets high in processed foods are associated with increased risk of obesity, heart disease, diabetes, and some types of cancer, so most nutrition experts agree that the Paleo Diet is 100% correct about the health benefits of cutting down on processed foods, added sugars, smoked and cured meats, and other such foods that contain less protein, fiber, minerals, vitamins, and phytonutrients than their unprocessed counterparts. Despite that agreement, critics say that much of the Paleo Diet research is based on very short-term studies lasting weeks to months, during which inflammatory markers are shown to decrease and that these benefits are seen in any diet that reduces or eliminates intake of added sugars and processed foods. In addition to the lack of evidence supporting the health claims made by Paleo Diet advocates, critics point to numerous, decades-long research studies in large populations of people as support that a plant-based diet—including grains and legumes—is the best-demonstrated eating pattern for optimal health.
Hundreds of studies support the Mediterranean diet, the Okinawan diet, vegetarian and vegan diets, and the diets of indigenous South Africans and Central and South Americans as healthful options. All of these eating patterns are associated with decreased risks of obesity, heart disease, diabetes, allergies, autoimmune diseases, neurodegenerative diseases (Alzheimer’s and dementia), and many types of cancer.
Critics also point out that there is no such thing as one true “Paleo Diet,” pointing to anthropological data and studies on ancient fossils, teeth and bones, and cook sites, which show that diet varied significantly by location. Paleolithic people who lived near the coast likely ate diets heavy in fish, nuts, seeds, berries, and other seafood; those living in arctic regions consumed vast quantities of fat and protein from fish, whales, and seals, with very little vegetables and fruit; and Paleolithic people living in semi-arid to temperate regions consumed significant quantities of potatoes and other starchy tubers, non-cultivated corn (wild-growing ancestors to the modern corn plant), legumes, and fruit.
According to critics, many of the “anti-nutrients” and “toxicants” in grains and legumes that Paleo advocates say we need to avoid are completely broken down by cooking and other forms of processing, and there is scant evidence that avoiding these foods truly eliminates these components from the diet. Many foods other than grains and legumes, including many root vegetables and some fruit, contribute these same “anti-nutrients,” such as lectins, to the human diet.
Critics also note that many Paleo Diet supporters erroneously assume that the human genome has changed very little in the past 10,000 years. But over the course of the past several thousand years, human genes have evolved, such as the “new” lactase gene, an enzyme that developed to allow humans to break down the lactose in dairy. Further, it isn’t only humans who have evolved in the past 10,000 years. Nearly all of the foods available to hunter-gatherers in the Paleolithic era are unavailable to humans today.
Critics also question the Paleo Diet advocates’ definition of health in ancient humans. The average lifespan of humans hovered at just around 49 years at the turn of the 20th century; longevity and the chronic diseases that accompany it are a recent phenomenon for most of the population.: in the Paleolithic era, many did not live past childhood, so most human ancestors didn’t live long enough to die of heart disease, diabetes, or cancer, though evidence suggests that people in the Paleolithic era who did make it to a ripe old age likely suffered many of the same health woes as modern man, including atherosclerosis.
There is no doubt that a Paleo Diet is far superior to the modern Western or American diet, which contains far too much processed food and added sugars. The jury is still out on whether the Paleo Diet is truly a better option than proven dietary strategies to reduce chronic disease risk.