Recommendations for reporting whole-grain intake in observational and intervention studies

The finding that people who eat the most whole grains have a lower risk of cardiovascular disease and diabetes, compared with those who eat the least, is one of the most consistent findings in nutritional epidemiology. However, criteria for reporting whole-grain intake have varied widely, making it difficult to precisely explore the relation of whole grains and grain components with health outcomes. To enable better understanding of the health benefits of whole grain rich diets, we propose that both observational and intervention studies should as far as possible be required to report as follows when describing whole grains: 1) quantify the amount of whole grain in the food or product in grams on a dry-weight basis, 2) describe the whole-grain definition used, 3) report and separate the different types of grains used, 4) if possible, report the structure of the grains (intact, crushed, partially milled) in foods, and 5) describe the main types of products used and processes used to make them. Added bran and germ should be reported distinctly from whole grains. In addition, we strongly recommend the incorporation of biomarkers of whole-grain intake to check compliance to intervention diets and help attenuate for errors in dietary recall of whole-grain intake. Of these measures, reporting whole-grain intake in grams is essential for future research work in the area. Improving reporting and estimation of whole-grain intake will enable easier comparison between different studies and lead to stronger meta-analyses in the future.