Quiz: What do Miley Cyrus, Matthew McConaughey, and Jessica Biel have in common with a caveman? If you guessed looks, you probably don’t watch TV. But if you guessed mealtime behaviors, then you likely have heard of the very popular Paleolithic (or Paleo) diet which both celebrities and non-celebrities alike embrace with enthusiasm.
What is it? The premise behind the The Paleolithic diet is that the human genome has remained relatively constant over the last 10,000 years while our diet and lifestyle have become more diverse. Consequently, Paleo diet supporters contend that there is a genome-diet mismatch which could underlie the increase in chronic diseases such as cardiovascular disease and diabetes. To address this imbalance, therefore, Paleo diet plans contain only the preagricultural food groups of meat, seafood, fruits, vegetables, and nuts. Hundreds of websites promote it, eager advocates blog about it, and the popular press loves to write about it.
Why is it beneficial? There are many intriguing studies on the Paleo diet providing evidence of effectiveness as well as mechanisms underlying observed benefits. For example, in sedentary adults and patients with Type II diabetes, the Paleo diet improves glycemic control and lowers blood pressure and body weight while improving cholesterol values. The Paleo diet may be more satiating than the heart-healthy Mediterranean diet, perhaps due to its higher composition of protein and polyunsaturated fatty acids. It should be cautioned, however, that these results are typically derived from small studies which often encompass substantial methodological issues. Data from rigorous, large clinical trials looking at long-term outcomes from the Paleo diet are lacking.
What are the problems? Well, it’s costly. It is estimated that for low-income adults, a 9% increase in income would be required to comply with the Paleo diet AND meet the daily recommended intakes (DRIs) of all micro- and macro-nutrients except for calcium. Furthermore, it requires followers to eliminate dairy and grains, which have substantial musculoskeletal, cardiovascular and metabolic health benefits. And finally, the Paleo diet involves eating meat, and a lot of it. As this NPR clip discusses, high levels of saturated fat from animal protein can increase cholesterol levels and may contribute to heart disease risk. It is not known how much meat is “too much,” but strong evidence indicates that high levels of red meat, in particular, augment mortality risk.
Conclusions? At this point, the evidence simply isn’t strong enough to recommend the Paleo diet; nor are there long-term studies convincing enough to refute its utility. However, as with any diet, one must consider whether it is a sustainable lifestyle that can be maintained over the course of a lifetime. And, of course, with respect to that, there just aren’t any cavemen around to ask.