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Nutrition

Paleo says no to grains. But is it justified?

The Paleo (Paleolithic) diet, designed to replicate the diet of pre-agricultural hunter-gathers, lay somewhat dormant following its inception in the 1970s. However a recent surge in popularity has seen Paleo jump to the top of the ultra-fickle ladder of ‘in’ diets.

Popularity has given rise to increased scrutiny, a particular focus of which has been the foods that are forbidden. While barring heavily processed snacks, soft drinks and alcohol appears logical, the exclusion of entire food groups including dairy, grains (cereals) and legumes is far less obvious.

At a high level, proponents of the Paleo diet argue that humans have not genetically adapted to process the foods banned on a Paleo diet, a claim that has been widely disputed.  Of particular interest is the exclusion of grains given their importance as a dietary staple the world over.

Dr. Loren Cordain, a leading expert on the Paleo diet, cites low levels of some vitamins and minerals and the presence of antinutrients in grains as grounds for their exclusion.

In his research, Cordain refers to several studies that link grain consumption with deficiency in vitamins A, C and B12 and minerals calcium and sodium. Importantly however these studies were undertaken in regions of the developing world where dietary variance is very limited and where grains account for the bulk of dietary intake. Cordain himself notes that in the developed world, where diet is varied, the nutrient content of grains is inconsequential.

Antinutrients are compounds found in foods that can inhibit the body’s absorption of certain nutrients. Although present in grains, antinutrients are commonly found in Paleo-approved foods such as fruits, vegetables, nuts and seeds. Interestingly phytic acid, an antinutrient heavily demonised by Paleo advocates for its inhibition of iron and zinc absorption, is found in higher quantities in nuts than in grains.

Oxalic acid, an antinutrient with similar absorption inhibitory capacities to phytic acid is also found in the highest quantities in leafy greens. Again research indicates that adverse effects from antinutrients appear in populations where dietary variety is limited. A varied diet and cooking/processing of foods largely safeguards against the undesirable effects of antinutrients.

Paleo diet literature also overlooks evidence demonstrating that antinutrients and the foods that contain them offer significant health benefits including helping to reduce the risk of cardiovascular disease and some cancers.

Dietary variety is universally recognised as key in avoiding nutrient deficiencies. A diet consisting of a limited assortment of foods, whether ‘Paleo’ or otherwise is suboptimal. To preclude grains based on deficiencies experienced in populations largely restricted to a staple grain disregards this fundamental principle. It appears paradoxical that Paleo advocates should justify limiting dietary variety based on research that clearly highlights a lack of variety as the root cause of deficiencies.

While the Paleo diet does present itself as a healthy option, its grounds for prohibiting certain food groups, or at least grains, appears to be predicated on little substantial evidence.

Author: Tim McHutchison
Bachelor of Food and Nutrition student, Deakin University

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About Deakin Nutrition

Nutrition and dietetics has a long history at Deakin with a world-leading research profile, and degree programs in high demand taught by engaged teaching staff

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