Leading researchers of whole grain intake recently proposed a set of best practice recommendations for other researchers to use when studying the effect of whole grain intake on health. This marks a significant step for the future of whole grain research as adoption of these best practice guidelines will lead to more specific measurement and analysis of the effect of total whole grain intake, and the consumption of different types of whole grains and whole grain foods on health outcomes. Here we review these best practice guidelines and profile the latest study to adopt these guidelines, which confirms that whole grains may help you live longer.
Whole grains have long been recognised as a hallmark to a healthy diet, being nutrient dense with over 26 nutrients and phytonutrients. The evidence is clear that people with a higher whole grain intake have a better diet quality and are 20-30% less likely to develop chronic diseases such as type 2 diabetes, heart disease and some cancers(1).
Whilst research clearly supports the health benefits of higher whole grain intakes, the actual definition of whole grain food used in many previous studies often classifies high bran grain foods as whole grains, but these foods do not technically meet the Food Standards Code (or more recent international definition) of the whole grain(2, 3). Consequently, much of the research which supports whole grains equally supports high fibre grain foods, which is one of the reasons why the Australians Dietary Guidelines encourage Australians to enjoy grains, mostly whole grain and/or high cereal fibre varieties.
Adopting the most up-to-date whole grain definition provides the opportunity to understand, more precisely, the health effect of total whole grain versus cereal fibre and the health effects of different types of whole grains and whole grain foods.
A recent Scandinavian study of over 120,000 people has taken the lead on adopting these best practice guidelines and provided a definition of whole grain which aligns with the most up-to-date definition, specified the types of whole grain and whole grain foods used and described the associated health outcomes(4).
This study demonstrated that people with the highest intake of whole grains had a 1-17% reduced risk of early death, regardless of the type of whole grain (wheat, oat, rye) or whole grain products (breakfast cereals, whole grain bread) consumed. Further disease specific analysis revealed that those who consumed the most whole grain food products had a 14-44% reduced the risk of death from cancer and coronary heart disease, compared to those who ate the least. Eating a variety of whole grains (i.e. oats, wheat, rye) was also shown to decrease risk of death by coronary heart disease in both men and women by 26% and 35% respectively.
Interestingly, this study also demonstrated that different whole grain foods may offer unique health benefits. For instance, those who had the highest intake of whole grain bread (either rye or mixed grain) had a 22-28% reduction in risk of death from any cause. Additionally, people who consumed the most whole grain breakfast cereal were shown to have a 15-25% decreased risk of death from cancer, a 25-47% decreased risk of death from coronary heart disease and 55-72% decreased risk of death from type 2 diabetes, compared to those who ate the least. This is good news for Australian’s as breads and breakfast cereals have been shown to be the largest contributors to whole grain intakes(5).
Different types of whole grains such as oats, rye and wheat were also shown to have unique health benefits. Women with the highest intakes of oats and wheat, had a 16% and 26% reduction in risk of cancer mortality, compared to those who ate the least. A higher intake of oats was also shown to reduce risk of death from diabetes by 75% in women and 60% in men, compared to those with the lowest intakes. These findings align with previous research which showed that soluble fibre found in oats, known as beta-glucan promotes optimal blood glucose control and improves the insulin response after a meal(6, 7).
With the introduction of best practice recommendations for the measurement and reporting of the effect of whole grains on health, it is likely in the coming years we will see a new wave of whole grain research which provides us a deeper understanding of the unique benefits of whole grains and whole grain foods. The emerging research using the recommendations indicates it strengthens the evidence that higher whole grain intakes are a powerful dietary strategy to improve nutrition and reduce the risk of chronic disease. Unfortunately, despite our current understanding of the benefits of higher whole grain intakes the majority of Australian adults and children are falling short whole grain recommendations(5).
In support of the Australian Dietary Guidelines, GLNC recommends that all Australians should aim to enjoy grain foods 3-4 times per day, choosing at least half as whole grain or high fibre foods. For a guide to boost your whole grain intake, check out GLNC’s Fact Sheet Whole grain foods – A hallmark of a healthy diet.
References
- NHMRC. Australian Dietary Guidelines Providing the scientific evidence for healthier Australian diets. 2013 Accessed online January 2014.
- AACCI. AACCI’s Whole Grains Working Group Unveils New Whole Grain Products Characterization 2013 [cited 2014 May ]. Available from: http://www.aaccnet.org/about/newsreleases/Pages/WholeGrainProductCharacterization.aspx.
- Ross AB, Kristensen M, Seal CJ, Jacques P, McKeown NM. Recommendations for reporting whole-grain intake in observational and intervention studies. The American journal of clinical nutrition. 2015.
- Johnsen NF, Frederiksen K, Christensen J, Skeie G, Lund E, Landberg R, et al. Whole-grain products and whole-grain types are associated with lower all-cause and cause-specific mortality in the Scandinavian HELGA cohort. British Journal of Nutrition. 2015;FirstView:1-16.
- GLNC. 2014 Australian Grains and Legumes Consumption and Attitudinal Report. Unpublished: 2014.
- Tiwari U, Cummins E. Meta-analysis of the effect of beta-glucan intake on blood cholesterol and glucose levels. Nutrition. 2011;27(10):1008-16.
- Tosh SM. Review of human studies investigating the post-prandial blood-glucose lowering ability of oat and barley food products. European journal of clinical nutrition. 2013;67(4):310-7.
