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We have long been urged to swap processed white flour for whole-grains. For those of us who have resisted the change, new research coming out of Harvard University may provide the final shove we need. According to Dr. Qi Sun, assistant professor of nutrition at the Harvard T. H. Chan School of Public Health in Boston, making that one change to whole-grains could reduce our risk of dying.
"The higher the whole grain intake, the lower the overall risk of dying, especially from cardiovascular disease." says Dr. Qi Sun, the study's author.
What are whole-grains?
Unlike refined white grains, whole-grains contain the entire grain kernel. This includes the bran (outer husk), germ (core), endosperm (middle-layer), and lots of nutrients that are usually lost in the refining process (such as fibre, iron, and B-vitamins).
In the refining process, the kernel is milled, removing the bran, germ and many of those healthy nutrients.
Whole-grain foods include bread made with whole-wheat flour, oatmeal, brown rice, and whole cornmeal.
What about this study?
Dr. Qi Sun and his colleagues reviewed the findings of a dozen studies, and examined data from the National Health and Nutrition Examination Surveys (NHANES). This provided Sun and his colleagues with data from nearly 800,000 patients, both men and women, in populations from the UK, Scandinavia and the United States.
In the period the study covered, 1971 to 2010, there were 98,000 deaths recorded.
While a direct cause-and-effect relationship wasn't proven, the study did suggest a link between eating more whole-grain foods and having a lower risk of dying.
The analysis suggested that eating three portions of whole grains every day led to a 25% reduction in the risk of dying from heart-attack or stroke, compared with patients who ate fewer or no portions of whole grains.
Why is that?
Cardiovascular disease is the number-one killer of both men and women in the USA. Anything that cuts your risk by a quarter has to be a good thing. But why are whole-grains so heart healthy?
One factor is the lower risk of hypertension (high blood pressure). A study by Wang and colleagues found that consuming four portions of whole-grains a day reduced the risk of hypertension by 23% in men. Tighe and colleagues also reported lower systolic blood pressure (the top number) in healthy adults who ate three portions of whole-grains a day. High blood pressure is one of the earliest contributory factors to heart disease.
Mellen and colleagues noted that more whole-grain consumption leads to improvements in coronary artery intima thickness and diameter (this is one of the ways they spot coronary artery atherosclerosis, plaque in the arteries). This suggests that high wholegrain intake is associated with less atherosclerosis, a risk for deadly blood clots, heart-attack and sudden death.
Consuming whole-grains is also associated with a reduced stroke risk of 30 to 36% and a reduced risk of heart attack of 25 to 28%.
The world's leading health organisations recognise the importance of eating wholegrains to keep your heart healthy. This includes: the U.K. Joint Health Claims Initiative, the U.S. FDA, and the Sweden and Danish Dietary Recommendations. In the U.K, a product with more than 51% whole-grains can claim: "People with healthy hearts tend to eat more whole grain foods as part of a healthy lifestyle".