WASHINGTON, DC, US – A study published Sept. 6 in Frontiers of Nutrition found removing foods containing enriched refined grains led to an increased percentage of Americans not meeting recommendations for several shortfall nutrients, including fiber, folate, iron and magnesium.
“Whenever you remove entire food groups or a majority of foods from select food groups, you will have nutrient shortfalls and likely will not have the kind of energy needed to sustain your daily activities, and grains are no exception,” said Stacey Krawczyk, principal consulting registered dietitian for the Grain Foods Foundation and president of FoodWell Strategies. “There are not many peer-reviewed studies out there that examine the nutrient contributions of staple refined, enriched and fortified grains in the American diet, so the hope is that this data will provide people with the understanding they need to help recover potential nutrient shortfalls in their diet.”
Yanni Papanikolaou, vice president of Nutritional Strategies, Paris, Ontario, Canada, and Victor L. Fulgoni III of Nutrition Impact, Battle Creek, Michigan, US, conducted the study. The Washington-based Grain Foods Foundation granted an honorarium to help support and fund the research but was not involved in the study design, collection analysis, interpretation of data, the writing of the article or the decision to submit it for publication.
The researchers used data from the National Health and Nutrition Examination Survey (NHANES) 2009-2016 to estimate usual daily intake of shortfall nutrients as defined in the Dietary Guidelines for Americans. The NHANES sample included 11,169 US adults of the ages 19 to 50 and 9,641 US adults of the ages 51 to 99. Two days of 24-hour dietary recalls determined usual intakes by using the methodology of the National Cancer Institute.
Based on NHANES data, the percentage of adults above the adequate intake (AI) level for fiber was 3.8% for the younger age group. Removing 25% of grains from the diet lowered the percentage to 2.6%. Removing 50% of the grains lowered it to 1.8%, and removing 100% of the grains lowered it to 0.7%. In the older age group, 14.1% met the AI level for fiber, but removing 100% of the grains from the diet lowered the percentage to 3.6%.
Among the younger adult group, 11% fell short of the AI level for folate. Removing 100% of the grains from the diet increased the percentage to 43.4%. In the older adult group, 13.8% fell short of folate intake, and removing 100% of the grains increased the percentage to 56.2%.
The percentages for not meeting the estimated average requirement (EAR) for iron were 8.4% of younger adults and 0.8% of older adults. Removing 100% of the grains from the diet increased the percentages to 10% for younger adults and 22% for older adults. About 51% of younger adults and 54% of older adults were below the EAR for magnesium. Removing 100% of the grains from the diet increased the percentages to 68% and 73%, respectively.
“Since whole grains are typically not included in government-mandated fortification and enrichment practices in the US, there may be a misconception that refined and/or enriched grains are not required in the American diet,” the researchers said. “Indeed, while the 2015 DGAC (Dietary Guidelines Advisory Committee) recommended making half of total grain intake as whole grain, the inclusion of refined grains in the diet was supported by modeling studies that demonstrated the nutrient contribution of fortified and enriched grains.
“Furthermore, the perception that all refined grains are negative dietary components may lead to unintended nutrient intake and public health consequences. Indeed, the classification of all grains into the classification of refined grains when criteria for whole grain are not satisfied may be nutritionally flawed since many enriched grains (i.e., breakfast cereals, bread, cooked cereals, etc.) are nutrient-dense.”