Currently, there are no health claims that link grain products to diabetes benefits. But food manufacturers in the United States can use a whole grain heart health claim based on the statement that diets rich in whole grain foods and other plant foods and low in total fat, saturated fat and cholesterol may reduce the risk of heart disease and some cancers.
However, there is very little scientific evidence to actually support the use of such claims based on the US Food and Drug Administration’s (FDA) definition of whole grains, concluded the Life Sciences Research Office (LSRO) in its new report.
“A consistent definition of whole grains has not been applied in existing research that investigates the health benefits of consuming whole grains,” wrote the group in its report entitled “Whole grain intake and cardiovascular disease and whole grain intake and diabetes: A review”.
LSRO was requested by cereal giant Kellogg to conduct a third-party evaluation of the effect of strict application of the FDA definition of whole grains on the scientific basis for whole grain claims.
Whole grains defined
The definition of what exactly constitutes ‘whole grain’ has been a topic of heated debate for some time.
In 2006, FDA adopted a definition proposed by the American Association for Cereal Chemists (AACC).
This defines whole grains as consisting of the intact, ground, cracked or flaked fruit of the grains whose principal components – the starchy endosperm, germ and bran – are present in the same relative proportions as they exist in the intact grain.
Benefits confused
However, a lot of the studies demonstrating the benefits of the grains use a broader definition, which includes other principal components such as bran and germ.
LSRO reviewed scientific literature published through February 2008. It considered 29 and 21 human intervention and observational studies for the association between whole grains and heart health and whole grains and diabetes respectively.
The group’s scientific review first examined studies that defined whole grains according to FDA’s definition. It then expanded its analysis to include studies with a broader definition.
It found that drawing specific conclusions on benefits of whole grains in general from the body of scientific evidence is confounded, typically with bran/dietary fiber.
“Applying the FDA definition of whole grains excludes the majority of observational studies, because they include the intake of bran and germ to evaluate the health effect of whole grains, and a great number of intervention studies that use individual grains, because they do not explicitly state that the endosperm, bran and germ are present in the same proportion,” wrote LSRO.
The group also concluded that the health effects of consuming whole grains is not consistent for all types of the grains because of their different macronutrient, micronutrient, and bioactive components.
In addition, LSRO said that that the scientific evidence on the relationship of whole grain consumption and diabetes is “suggestive but inconclusive” whether the analysis was restricted to studies that defined whole grain according to the FDA definition, or included studies using a wider classification of whole grains.
More studies
The Whole Grains Council (WGC), a non-profit nutrition group that promotes the consumption of whole grains, said it backs Kellogg’s focus on the need for more research into the benefits of the grains.
Cynthia Harriman, the organization’s director of food and nutrition strategies, agreed that research on some health benefits is currently inconclusive due to the inconsistent definitions of whole grains, and stressed the importance of more funds for additional studies.
"The Whole Grains Council applauds Kellogg for focusing attention on the importance of additional research into the health benefits of whole grains. It's important to use common sense in digesting the conclusions of this report; we need to keep working to get more whole grains in our diets, even as we make an effort to untangle the remaining mysteries behind their health benefits," she told NutraIngredients-USA.com.
Harriman said the WGC is currently completing a compilation of recent research to support the work of the 2010 Dietary Guidelines Advisory Committee.
Kellogg did not respond to calls for comment in time for publication this morning.