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Harvard Commentaries
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Food for Thought Food for Thought

The "Paleo Diet" -- Back to the Stone Age?

October 04, 2013

By Elizabeth Lundy, B.S.
Brigham and Women's Hospital

We usually look to the latest nutrition research to uncover "super foods" that help promote weight loss and prevent disease. But should we be looking to the past instead of the present or even the future for these foods?

According to Loren Cordain, Ph.D., the healthiest diet is one that our ancestors ate 10,000 years ago – during the Paleolithic era.

Cordain is the founder of the "Paleo" movement. His diet, the Paleolithic Diet, restricts what you eat to foods the hunter-gathers of the Stone Age ate.  Here's an example of what you can and can't eat: 



Meat (especially game meat), poultry, fish, and shellfish

Any food that is processed, man-made  or prepackaged

Fresh fruits

All grains

Fresh vegetables

Legumes (including peanuts)







Olive, coconut and flaxseed oils

Vegetable oils




The Risks

At first glance, the Paleo Diet is rich in many of the foods nutrition professionals stress – fresh fruits and vegetables, healthy fats, lean protein, and limited amounts of sodium and sugar. Even without whole grains, oats and lentils, a diet rich in fruits and vegetables can still provide adequate amounts of soluble and insoluble fibers

The downside of the Paleo Diet is the risk of certain nutritional deficiencies.   

  • Cutting out all grains and legumes removes sources of certain B vitamins, such as thiamine, folate, niacin and riboflavin. 
  • Excluding dairy could lead to a calcium deficiency.

These can be avoided by eating organ meats, especially liver, which provide B vitamins. Dark leafy greens and fish  such as sardines with the bones, are good sources of calcium.  Without grains, legumes and dairy, vegetarians may be hard pressed to eat enough protein. (Soy is out because it's a legume.) By eliminating entire food groups, the Paleo Diet appears nutritionally incomplete. 

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What the Diet's Supporters Say

Supporters of the Paleo Diet also claim that our ancient ancestors who ate this way didn't suffer from the diseases that plague the modern world: health and blood vessel disease (cardiovascular disease), type 2 diabetes, gout and osteoporosis. Does the evidence back up these claims? 

Diseases the Paleo Diet claims to help prevent or treat

Current research

Cardiovascular disease

Diets that contain whole grains and legumes actually reduce risk of developing cardiovascular disease.

Type 2 diabetes

Diabetes is caused by a combination of genetics risk and overall overweight or obesity – not by eating carbohydrates. If you gain weight following the Paleo Diet, you still increase your risk of developing diabetes. 


Nutrition therapy for gout actually recommends eating less meat and fish, and more grains and dairy.


This condition is strongly linked to calcium deficiency. Given this diet's lack of dairy foods, it's puzzling that it claims any benefit for osteoporosis.


There is no strong scientific evidence at this time for claims that a Paleo Diet helps prevent or treat many medical conditions. Much of what we know about 10,000 years ago is an inference, based on studies of skeletal remains and human artifacts. Our understanding on exactly what composed a true paleolithic diet, and in what quantities, is at most an educated guess.

Overall, a Paleo Diet certainly has its merits. It stresses whole foods rather than prepackaged and processed foods. This can help reduce sodium and sugar in our diets. However, it can lead to serious deficiencies. 

Even if the claims of the Paleo Diet can be validated, you can't separate it from the overall lifestyle of that age. The rigorous physical demands of living outdoors, hunting, gathering and foraging for food surely contributed to the overall health of these people. Thus, rather than being seen as the ultimate solution to good health, the Paleo Diet should be considered just one of many dietary options.   

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Elizabeth Lundy recently completed her dietetic internship at Brigham and Women's Hospital, and is on her way to becoming a registered dietitian. Prior, she completed her Bachelor of Science degree in nutrition at the University of Massachusetts Amherst.

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