A recent study at Harvard T.H. Chan School of Public Health, Boston has found that eating whole grains could lower the risk of death.
The study published in American Heart Association’s journal, Circulation found that people consuming about 4 servings of whole grains (70 grams/day) had a 22% reduced risk of premature death during the study period, compared to those who consumed little or no servings of whole grains. The overall 20% decline constituted 23% for cardiovascular deaths and 20% for cancer-related deaths.
Dr. Qi Sun (assistant professor, Department of Nutrition) and colleagues reviewed the results from 12 published studies as well as unpublished results from the National Health and Nutrition Examination Survey (NHANES). The study spanned between 1971-2010 for the population from the United States, the United Kingdom and Scandinavian countries, including 786,076 participants.
What is whole grain?
Cereal grains which contain the germ (nutrient-rich center), endosperm (middle layer) and bran (outer skin) are called whole grains (e.g., brown rice, whole wheat, oatmeal popcorn, etc). During refining these are milled, removing the germ and bran along with the key nutrients (iron, vitamin B, fiber). White rice, white flour and white bread contains refined grains.
Coming back to the study, several likelihoods for explaining health benefits of whole grains was put forward. With high fiber content, whole grains were found to lower the blood cholesterol level and regulate blood sugar. Moreover, the satiating power of fiber makes you feel full for longer; thereby cutting down your calories and reducing the risk of obesity.
As Dr Qi Sun says, “These findings further support current dietary guidelines that recommend at least 3 daily servings (or 48 grams) of whole grains to improve long-term health and prevent premature death.”
Researchers also noted that low-carbohydrate diets that ignore the health benefits of whole grains foods should be adopted with caution as they might be linked to higher cardiovascular risk and mortality.
On the other hand, this analysis had some limitations as well.
Firstly, a rigid definition of whole grains was available after the study, because of which the list of whole grain food or sources varied substantially among individual studies. Moreover, researchers are not sure whether the findings from this study can be generalized to other populations, as most of the studies were from the U.S. and Scandinavian countries. Furthermore, the group says that there might be some inevitable measurement error and misclassifications of the participants arising from day-to-day variations and variation of whole grain contents between and within food items. Lastly, they pointed out potential limitation due to the variation in the health condition of participants during the study which might change the diet at baseline.
Nonetheless, the researchers recommend having food (e.g., such as quinoa, oatmeal, and bran) that at least have 16 grams per serving of whole grain content.
While the health experts have been recommending the whole grains in dietary regulations for a long time, this study is first of it’s kind linking the whole grains to mortality risk.
The original work can be accessed here: Circulation