The Cooper Institute

Founded in 1970 by the "Father of Aerobics"
Kenneth H. Cooper MD, MPH


Whole Grains Study Delivers Severe Blow to Paleo Enthusiasts

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Eat better

Thursday, Apr 09, 2015

An earlier blog, Should You Eat Like a Caveman?, covered the rationale behind the Paleo Diet as well as benefits and concerns with this approach. A major emphasis of the Paleo Diet is to avoid grains, including whole grains. Although there is no scientific evidence to support their opinion, Paleo enthusiasts claim that grains ‘cause inflammation’, which leads to an increased risk of chronic disease and early death. Before we take a look at what the science says, let’s review a little bit.

All grains contain 3 parts: the bran, germ, and endosperm. A whole grain uses all 3 parts of the grain. Refined grains only use the endosperm. This is important because different nutrients and phytochemicals* are found within each part of the grain plant. Thus, whole grains are nutritionally superior and contain more fiber than refined grains.

In 2007, a study of 161,737 women enrolled in the Nurses’ Health Study (NHS) was published.1 This study focused on dietary intake of whole grains, bran, and subsequent risk of developing type 2 diabetes. All women were healthy at baseline, and completed dietary questionnaires at regular intervals during the 12-18 year follow-up. During this time, 6,486 women developed type 2 diabetes. All women were assigned to one of five groups based on their average daily whole grain and bran intake. Women within the highest intake group were nearly 40 percent less likely to develop type 2 diabetes as compared to women within the lowest intake group. These relationships were similar when dietary bran intake was evaluated. Based on pooled data from 5 additional published studies on this topic, researchers concluded that for every two servings per day increment in whole grain consumption, there was a 21% decrease in risk of developing type 2 diabetes.

Although we know that increased whole grain intake is associated with a reduced risk of type 2 diabetes and cardiovascular disease (CVD), less is known about whole grains and risk of mortality (death). For that reason, a major study was recently published in JAMA Internal Medicine.2 A total of 74,341 women from the NHS and 43,744 men from the Health Professionals Follow-up Study were enrolled, all subjects were healthy at baseline. Over a ~25 year period, subjects completed validated food frequency questionnaires every 2-4 years. During the follow-up there were a total of 26,920 deaths. At the completion of the data collection period, subjects were placed into five groups according to their average daily intake of whole grains. There was a statistically significant ~10% reduction in all-cause mortality among subjects with the highest intake of whole grains compared to subjects with the lowest intake of whole grains. The trend was even more significant with regard to CVD mortality, with subjects in the highest intake group benefitting from a 15% reduction in the risk of CVD mortality compared to subjects in the lowest intake group. So now we have convincing evidence that increased consumption of whole grains is associated not only with significantly lower morbidity (illness), but lower mortality risk as well. Because of the large sample sizes, long follow-up periods, and significant numbers of events in these studies, this is equivalent to landing a ‘haymaker’ to the Paleo approach.

As mentioned in the previous Paleo blog, there are some positive aspects to the diet. It restricts simple sugars and sodium, while promoting physical activity and green tea consumption. Individuals with gluten intolerance comprise a very small percentage of the U.S. population. These individuals should avoid wheat, barley, and rye because of the damage gluten can cause to their small intestine. However, for the remaining 98-99% of the population, the notion that grains are ‘bad’ for us simply does not hold up in the research world, particularly when we look at whole grains. The results of the studies mentioned previously and others are in line with current dietary recommendations to increase intake of whole grains to help prevent chronic disease and premature mortality.

While the Paleo Diet is moderately popular among exercise enthusiasts, there is strong evidence that increased consumption of whole grains decreases the risk of morbidity and mortality.


Tip: Seeing ‘multi-grain’ and ‘7-grain’ on a label does not always mean whole grain. When examining the list of ingredients, always look for the words ‘whole grain’ at the very beginning of the list! 

*phytochemicals are disease preventing non-nutrients that are only present in plant- based foods


To learn more about the relationship between nutrition and health or sports nutrition, consider taking the Nutrition for Health and Fitness (in Dallas or online) or the Sports Nutrition courses. The general public is welcome to attend these courses as well.


1De Munter JS, Hu FB, Spiegelman D, Franz M, van Dam RM. (2007). Whole grain, bran, and germ intake and risk of type 2 diabetes: a prospective cohort study and systematic review. PLoS Med. 4(8)e261.

2Wu H, Flint AJ, Qi Q, et. al. (2015). Association between dietary whole grain intake and risk of mortality: two large prospective studies in US men and women. JAMA Internal Med. Doi.1001.6283. Epub ahead of print.