Current standards for classifying foods as "whole grain" are inconsistent and, in some cases, misleading, researchers say.
One of the most widely used industry standards, the Whole Grain Stamp, actually identified grain products that were higher in both sugars and calories than products without the Stamp.
The researchers from the Harvard School of Public Health (HSPH) urge adoption of a consistent, evidence-based standard for labelling whole grain foods to help consumers and organizations make healthy choices.
This is the first study to empirically evaluate the healthfulness of whole grain foods based on five commonly used industry and government definitions.
"Given the significant prevalence of refined grains, starches, and sugars in modern diets, identifying a unified criterion to identify higher quality carbohydrates is a key priority in public health," first author Rebecca Mozaffarian said.
The health benefits of switching from refined to whole grain foods are well established, including lower risk of cardiovascular disease, weight gain, and type 2 diabetes.
Based on this evidence, the U.S. Department of Agriculture's (USDA) 2010 Dietary Guidelines recommend that Americans consume at least three servings of whole grain products daily, and the new U.S. national school lunch standards require that at least half of all grains be whole grain-rich. However, no single standard exists for defining any product as a "whole grain."
Mozaffarian and her colleagues assessed five different industry and government guidelines for whole grain products.
Firstly, the Whole Grain Stamp, a packaging symbol for products containing at least 8 grams of whole grains per serving (created by the Whole Grain Council, a non-governmental organization supported by industry dues).
Any whole grain as the first listed ingredient (recommended by the USDA's MyPlate and the Food and Drug Administration's Consumer Health Information guide).
Any whole grain as the first ingredient without added sugars in the first three ingredients (also recommended by USDA's MyPlate).
The word "whole" before any grain anywhere in the ingredient list (recommended by USDA's Dietary Guidelines for Americans 2010), and the "10:1 ratio," a ratio of total carbohydrate to fibre of less than 10 to 1, which is approximately the ratio of carbohydrate to fibre in whole wheat flour (recommended by the American Heart Association's 2020 Goals).
From two major U.S. grocers, the researchers identified a total of 545 grain products in eight categories: breads, bagels, English muffins, cereals, crackers, cereal bars, granola bars, and chips. They collected nutrition content, ingredient lists, and the presence or absence of the Whole Grain Stamp on product packages from all of these products.
They found that grain products with the Whole Grain Stamp, one of the most widely-used front-of-package symbols, were higher in fibre and lower in trans fats, but also contained significantly more sugar and calories compared to products without the Stamp.
The three USDA recommended criteria also had mixed performance for identifying healthier grain products. Overall, the American Heart Association's standard (a ratio of total carbohydrate to fibre of =10:1) proved to be the best indicator of overall healthfulness.
Products meeting this ratio were higher in fibre and lower in trans fats, sugar, and sodium, without higher calories than products that did not meet the ratio.
"Our results will help inform national discussions about product labelling, school lunch programs, and guidance for consumers and organizations in their attempts to select whole grain products," senior author Steven Gortmaker said.
The study has been published online in Public Health Nutrition. (ANI)