What’s the appeal of the Paleo diet?
Studies suggest it could have positive effects on heart and mitigate risk of diabetes
The Paleo diet has been the mostsearched diet on Google since 2013, yet it is not without controversy. Despite its popularity, many experts believe it could be harmful to our health. Concerns are substantial enough that a panel of nutrition and health experts ranked it last out of 35 diets in the “best diet” category of U.S. News and World Report, a multiplatform publisher of news and consumer rankings, for the past two years.
Despite the negative publicity, Paleo made its way into the spotlight again this month, when a systematic review and meta-analysis, considered the highest-level of research, was published in the American Journal of Clinical Nutrition.
The researchers from Bahrain and Netherlands determined that the Paleo diet resulted in better health improvements for those with metabolic syndrome, a cluster of symptoms that collectively indicate an increased risk for Type 2 diabetes or heart disease, than diets based on conventional health guidelines.
So, what is the Paleo diet, and is it as good — or as bad for you — as the headlines might lead you to believe? The diet defined The Paleo diet is a diet based on the types of foods humans are thought to have eaten during the Paleolithic period, which lasted from 2.5 million to about 10,000 years ago, the point at which humans shifted from a hunter-gatherer to a more agricultural way of life, introducing novel foods such as grains, dairy foods and legumes into the diet.
The diet includes natural sweeteners, fish (preferably wild), red meat and poultry, eggs, fruits and nonstarchy vegetables, along with coldpressed fats and oils such as coconut and olive oil. The list of no-nos includes all grains, dairy, legumes, processed food, refined oils, added sugar and alcohol (though some versions of the diet allow three drinks per week). Diet claims Paleo diet proponents, such as Dr. Loren Cordain, the author of the bestselling book, The Paleo Diet, claim that the advent of agriculturally derived foods also increased our collective risk for heart disease, cancer, Type 2 diabetes, bowel disorders, arthritis and acne. It’s said that post-agricultural foods such as grains and legumes are inflammatory, and contain anti-nutrients such as phytates and lectins that bind important nutrients, such as iron and calcium, and prevent their absorption. Some antinutrients, in particular the lectins found in legumes, are also said to harm the lining of the bowel, contributing to digestive disorders and disrupting our immune system. Supporting evidence Despite the widespread interest in the Paleo diet, to date only a handful of randomized, controlled trials (the gold-standard of research) have been conducted, comparing the diet to a control diet. In the first study, by Swedish researchers published in 2007, researchers randomly placed 29 patients with heart disease and either Type 2 diabetes or prediabetes on a Paleo- or Mediterranean-style diet. After 12 weeks on the diets, the subjects in Paleo group responded better to an oral glucose tolerance test (a test used to diagnose diabetes) versus those on the Mediterranean diet.
In the second study, by the same research team, 13 subjects with Type 2 diabetes were placed on either a standard high-fibre Diabetes Diet, or a Paleo diet for three months. Both groups were given support from a dietitian throughout the study. At the end of the study, the Paleo diet subjects lost more weight, and their blood sugars, triglycerides, diastolic blood pressure (the lower number) and good (HDL) cholesterol improved compared with those on the Diabetes Diet.
While the results of these studies seem encouraging (if you’re a Paleo proponent), they also come with an asterisk: the subjects on the Paleo diets ate fewer calories than the subjects on the control diet. So, positive effects could be the result of weight loss not because of the diet itself.
A 2014 study conducted by Dutch researchers tried to address this issue by randomly assigning 34 individuals with metabolic syndrome (a cluster of symptoms that are associ- ated with heart disease and Type 2 diabetes risk) to a Paleo-type diet, or a reference diet based on the Dutch Health Council guidelines.
Unlike the previous trials, however, the subjects were instructed to consume enough calories to keep their weight stable throughout the twoweek study. That way, any positive effect from the Paleo diet would be more likely due to the diet itself, not weight loss.
By the end of the study, the Paleo eaters had lower blood pressure, total cholesterol and triglycerides, and their “good” (HDL) cholesterol was higher than participants in the control diet.
To the authors’ surprise, the Paleo subjects managed to lose more weight than the control group (an average of three pounds), which suggests that either the subjects weren’t compliant with the diet, or that something about the Paleo diet promoted weight loss, even with the same number of calories consumed. The bottom line The Paleo diet is backed by a few interesting studies that suggest it could have some positive effects on heart health and diabetes risk. Whether that’s because people on Paleo diets tend to lose weight (which could be because so many foods are excluded on the Paleo diet), or because of the diet itself remains to be seen, but more well-controlled studies are clearly needed.
Critics argue that the Paleo diet is costly, difficult to maintain and based on foods that, despite being called Paleo, did not actually exist in hunter-gatherer times.
So, is the Paleo diet right for you? That depends: for some, it is a drastic lifestyle change that can be overwhelming. Others find the diet fits into their current habits and lifestyle. Some argue that a modified Paleo diet that excludes processed food, but includes some high quality grains, legumes and dairy could be a healthy option.
Regardless of whether or not you feel Paleo is right for you, there’s no doubt that a diet rich in fruits, vegetables, nuts, seeds and fish can help almost anyone get healthier. Jennifer Sygo is a registered dietitian and sports nutritionist at Cleveland Clinic Canada.