The report's authors, researchers at Bath University's School for Health, found only four out of 13 gluten-free brands on prescription were partially fortified with the micronutrients legally required for standard bread flour. These are iron, thiamin, niacin and calcium.
They said there was little data on the complete micronutrient content of gluten-free products, so assessing the nutritional adequacy of gluten-free diets was impossible.
They called for the development of a gluten-free product database in order to gain a more comprehensive picture.
They added that mandatory fortification of gluten-free bread products, as was the case with mainstream bread, warranted further consideration.