Whole Grains Could Benefit Health and Longevity, But Most Diets Fall Short

MedicalResearch.com Interview with:

Geng Zong, Ph.D. Research fellow at Harvard T.H. Chan School of Public Health Boston, Massachusetts.

Dr. Geng Zong

Geng Zong, Ph.D.
Research fellow at Harvard T.H. Chan School of Public Health
Boston, Massachusetts.

MedicalResearch.com: What is the background for this study? What are the main findings?

Response: The refining process of grains removes most of fiber, minerals, vitamins, polyphenols and alkyl resorcinols that mainly exist in the outer layer of a kernel, thus enriches grains with carbohydrate and energy. Whole grains, on the other hand, are cereal grains or processed cereal grains that contains bran and germ, in addition to the inner most endosperm, as their natural proportions in the kernel. Observational studies have repeatedly linked whole grain intake with major chronic diseases, including obesity, diabetes, cardiovascular diseases, and cancer, but findings regarding mortality are inconsistent and have not been quantitatively summarized. By meta-analyzing 14 existing or unpublished prospective cohort studies, our investigation found that whole grain intake is inversely associated with mortality risk from all-causes, CVD, and cancer. Among people with whole grain consumption, estimated all-cause mortality risk was 7% (for 10 grams/day), 16% (for 30 grams/day), 20% (for 50 grams/day), and 22% (for 70 grams/day) lower than people with no whole grain consumption. Similar dose-response relationship was observed for CVD and cancer mortality.

MedicalResearch.com: What should readers take away from your report?

Response: Previous and our findings collectively suggest that eating whole grains, in replacement of refined grains, could benefit health and longevity. However, whole grain consumption falls largely below recommendation in most countries. For example, Americans consume < 1 serving/day (approximately 16gram/day in dry weight), but USDA dietary guidelines recommend at least 3 servings/day of whole grains for adults (More generally, at least half of grain-based foods needs to be whole grains to facilitate potential benefit for all people). Of notice, grain-based foods are more than foods that “has” grains in these recommendations, it must contain 16 grams grains in dry weight for each serving. Otherwise, more servings are needed to reach this goal (approximately 48 grams of whole grains in dry weight per day, at the expense of refined grains).

MedicalResearch.com: What recommendations do you have for future research as a result of this study?

Response: Most epidemiological studies on whole grains have been observational, which limits any cause inferences on whole grains and health. Therefore, large-scaled intervention studies, which provide the strongest scientific evidences, are needed to confirm the benefit of whole grains. In addition, existing studies have mainly focused on cardiometabolic diseases and cancers. Given the various bioactive components of whole grains and findings that linked whole grain intakes with deaths of other causes (eg, infectious diseases, respiratory system diseases, and digestive diseases), further studies may want to explore the relationship between whole grain consumption and a wider range of health conditions. Lists of whole grain foods or food sources varied substantially among included articles. In this regard, a standard description of whole grain items and estimation method of whole grain intake in future studies will be helpful not only to the scientific community but also the translation of knowledge to the public.

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Whole Grain Intake and Mortality From All Causes, Cardiovascular Disease, and Cancer
A Meta-Analysis of Prospective Cohort Studies
Circulation.2016; 133: 2370-2380doi: 10.1161/CIRCULATIONAHA.115.021101

Geng Zong, Alisa Gao, Frank B. Hu, and Qi Sun

Note: Content is Not intended as medical advice. Please consult your health care provider regarding your specific medical condition and questions.

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