The Paleo Diet: What’s the Story?

The Paleo diet is championed by Dr. Loren Cordain, professor of health and exercise science at Colorado State University. Cordain proposes that eating the diet our hunter-gatherer ancestors (humans from the Paleolithic period) supposedly ate — a diet of meat, seafood, fruits, vegetables, and nuts — is healthier than the standard American diet, Atkins-style low-carb diets, and vegetarian and vegan diets. Paleo is famous for eschewing grains, dairy, and processed food and extolling the benefits of free-range and wild meats. Officially, the suggested nutrient consumption from page 11 of the book is 19–35% protein, 22–40% carbohydrate, and 28–47% fat, with animal-based foods served at virtually every meal.1

A major piece of evidence that Cordain uses to support the concept of our ancestors eating such high levels of animal-based foods, protein, and fat is data he extracted from an epidemiological study he conducted of the diets of 229 modern-day hunter-gatherer societies.2However, his assumption that these modern-day societies were consuming diets representative of those of humans in the Paleolithic period is a stretch, as demonstrated by researchers who analyzed the geographic conditions associated with the plant-to-animal-food ratio of these same modern societies. They concluded that the relevance of their diets to true Paleolithic diets is dubious, given that modern hunter-gatherers live much farther from the equator than Paleolithic societies did.3In addition, evidence as far back as 30,000 years demonstrates that plant-food processing (grinding starch grains)4was done by humans of the era, at odds with the Paleo claim that eating grain is an unnatural and recent innovation.

The clear benefit is that Paleo eaters may be reducing or eliminating sugar and white flour, foods that are associated with the rising obesity epidemic.5So no arguments there, but what about the rest of the diet?

There is no evidence that we actually need more than the amount of protein specified in the USDA Dietary Reference Intake of ~0.8g/kg body weight per day.6And, as we have seen, thanks to Dr. Campbell and others, there is substantial evidence that excess animal protein consumption increases cancer7and accelerates cancer progression8, whereas reducing total protein consumption may be able to reverse the cancer process. Simply because humans ate some amount of meat in the past does not mean that eating it now is the best idea. We are fortunate to have so many food options available, and our greatest chances for good health and long life come from a whole food, plant-based diet.

To adequately fulfill nutritional requirements, a diet of 10% protein, 10–15% fat, and 75–80% carbohydrate can be achieved by eating a whole food, plant-based diet without any special attempt to “get enough” protein or fat. The Paleo diet promotes an unhealthy excess of protein (especially animal protein), far too few carbohydrates (which our bodies need as their primary energy supply), and a huge amount of fat.

Although Dr. Cordain claimed not to promote refined oils in a recent debate with Dr. Campbell,9the recipes in his book suggest otherwise. The Paleo diet, with its liberal use of oils, is hardly natural, as even the “best” oils do not resemble whole natural foods. Paleo fans of mayonnaise may be pleased to learn that Brockway Tuna Salad on page 172 of Dr. Cordain’s book contains — cup of homemade mayonnaise, which is almost entirely oil. The recipe serves one.10

To check the consistency of Paleo recommendations, I analyzed the nutrient content of 7 days of Paleo Phase Two (the maintenance level of the diet — what long-term Paleo eaters are encouraged to follow) and posted it to PlantBasedResearch.org.11I used the USDA SuperTracker, an online nutrition analysis tool that derives its data from the USDA Nutrient Database. The meal plans are from pages 152–153, using relevant recipes from the back of the book.

My conclusion: If a Paleo eater splurged on two oatmeal breakfasts and one tofu stir-fry dinner for the three permitted non-Paleo meals, he or she would average 26% protein, 30% carbohydrate, and 46% fat. These numbers are consistent with the Paleo-recommended intake ranges … and every bit as unhealthy. The diet would also provide 544 mg of dietary cholesterol per day (of which we need zero).

The Paleo diet has been rising in popularity, and many claim to feel better eating it, but that is more likely a result of having removing processed food, rather than having eaten nearly half one’s calories as fat.

1Cordain, Loren.The Paleo Diet: Lose Weight and Get Healthy by Eating the Food You Were Designed to Eat. New York: J. Wiley, 2002. Page 11.

2Cordain L, Miller JB, Eaton SB, Mann N, Holt SH, Speth JD., Plant-animal subsistence ratios and macronutrient energy estimations in worldwide hunter-gatherer diets.Am J Clin Nutr. 2000 Mar;71(3):682–92. Accessed online 08/2013 athttps://ajcn.nutrition.org/content/71/3/682.abstract?ijkey=f473fdeae03c8ff8335b8ef1e899ac68042f9d4c&keytype2=tf_ipsecsha

3Ströhle A, Hahn A, Sebastian A., Latitude, local ecology, and hunter-gatherer dietary acid load: implications from evolutionary ecology.Am J Clin Nutr. 2010 Oct;92(4):940–5. Accessed online 08/2013 athttps://ajcn.nutrition.org/content/92/4/940.long

4Revedin A, Aranguren B, Becattini R, Longo L, Marconi E, Lippi MM, Skakun N, Sinitsyn A, Spiridonova E, Svoboda J., Thirty-thousand-year-old evidence of plant food processing.Proc Natl Acad SciU S A. 2010 Nov 2;107(44):18815–9. Accessed online 08/2013 athttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC2973873/

5Malik VS, Willett WC, Hu FB., Global obesity: trends, risk factors and policy implications.Nat Rev Endocrinol. 2013 Jan;9(1):13–27. Accessed online 08/2013 athttps://www.ncbi.nlm.nih.gov/pubmed/23165161

6Dietary Reference Intakes (DRIs): Estimated Average Requirements. Food and Nutrition Board, Institute of Medicine, National Academies. Accessed online 08/2013 athttps://www.iom.edu/Activities/Nutrition/SummaryDRIs/~/media/Files/Activity%20Files/Nutrition/DRIs/5_Summary%20Table%20Tables%201-4.pdf

7Campbell, T. Colin, and Thomas M. Campbell. Introduction.The China Study: The Most Comprehensive Study of Nutrition Ever Conducted and the Startling Implications for Diet, Weight Loss and Long-term Health. Dallas, TX: BenBella, 2005. Pages 1–8.

8Youngman LD, Campbell TC., High protein intake promotes the growth of hepatic preneoplastic foci in Fischer #344 rats: evidence that early remodeled foci retain the potential for future growth.J Nutr. 1991 Sep;121(9):1454–61. Accessed online 08/2013 athttps://jn.nutrition.org/content/121/9/1454.full.pdf

9The Wall Street Journal streaming web debate, accessed online 08/2013 athttps://stream.wsj.com/story/experts-health-care/SS-2-135539/SS-2-253890/?mod=wsj_streaming_experts-health-care

10Cordain, Loren.The Paleo Diet. Page 172.

11USDA SuperTracker output for 7 days of Paleo Phase Two, posted on PlantBasedResearch.org and accessed online 08/2013 athttps://plantbasedresearch.org/sites/default/files/files/A%20Week%20of%20Paleo.pdf