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29.10.2015

Gluten-free diet has no effect on athletic performance

Athletes who turn to a gluten-free diet in the hope of improving their performance are wasting their time write Australian sports scientists, working at the University of Tasmania, in an article in Medicine and Science in Sports and Exercise.

Coeliac disease
Figures show that about 1% of the European and American population suffer from coeliac disease. Their small intestine is not capable of digesting the proteins in grains such as wheat, rye and barley. The inflammatory reactions that gluten causes in them are so serious that coeliac patients have to follow a gluten-free diet.

Some nutritional gurus also say that gluten can be dangerous to non-coeliacs too, and argue in favour of gluten-free or low-gluten diets. One of the groups for whom a diet like this is supposed to be good is athletes. And this message is being heard, the Australians reported in February 2015 in the International Journal of Sport Nutrition and Exercise Metabolism. [Int J Sport Nutr Exerc Metab. 2015 Feb;25(1):37-45.] According to that study of 910 athletes, 41 percent of competitive athletes eat gluten free either all the time or regularly.

But does the amount of gluten in a diet affect the athletic performance of people who have no gluten intolerance? This is the question that the Australians set out to answer in their publication in Medicine and Science in Sports and Exercise.

Study
The researchers put 13 trained cyclists aged 18-40 on a gluten-free diet for 7 days. At the end of this period the cyclists had to cycle as fast as they could for 15 minutes on an ergometer.

On another occasion the researchers put the cyclists on a weeklong 'normal’ diet to which they added a daily 16 g of gluten in the form of sports bars. Once again, the cyclists had to cycle for 15 minutes at the end of the diet.

The athletes did not know whether they were on a gluten-free or gluten-rich diet.

Results
The figure below is clear: in terms of performance capacity it makes not a jot of difference whether the cyclists had eaten a gluten-free or a gluten-rich diet.

The researchers also asked the cyclists how they were feeling, but found that diet had no effect on their mood.

The researchers measured the cyclists' concentrations of coeliac-related inflammatory factors such as intestinal fatty acid binding protein, interleukin-1-beta, interleukin-6, interleukin-8, interleukin-10, interleukin-15 and TNF-alpha, but none of these reacted either to the presence of gluten in the diet.

Conclusion
"Based on these findings it is recommended that athletes seek evidence-based advice before adopting a gluten free diet for non-clinical reasons to ensure that nutrition intake supports individualised and optimal fueling for sport performance", the researchers wrote.

Source:
Med Sci Sports Exerc. 2015 Dec;47(12):2563-70.

More:
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