- Most Americans consume more refined grains than whole grains.
- A new study looked at the impact on heart disease risk factors from eating refined vs. whole grains.
- The study found that replacing refined grains with whole grains may help lower waist circumference, blood pressure, and blood sugar levels, which may reduce heart disease risk.
New research published in The Journal of Nutrition looked at how whole grains and refined grains impact waist circumference, cholesterol, triglyceride, and blood sugar levels, which are all factors that may affect heart health.
You’ll often hear health experts recommend whole grains over refined grains, but may be confused about the difference.
“Whole grains include the entire grain and all its parts, which are the bran, germ, and endosperm,” explains Alka Chopra, RD, CDE, a dietitian and certified diabetes educator in Toronto, Ontario. “Whole grains come with the benefit of protein, fiber, vitamins, minerals, and antioxidants.”
Examples of whole grains include brown rice, whole grain wheat, oats, barley, buckwheat, amaranth, millet, quinoa, and corn.
“On the other hand, refined grains have been stripped of some of the three parts of the whole grain,” says Chopra. They exclude the fiber-rich bran and/or vitamin-rich germ, which eliminate much of the nutritional value.
Examples of refined grains include white rice and anything made with white flour, including bread, pasta, crackers, pretzels, and baked goods.
Past studies have linked diets with more whole grains to a decreased risk of developing heart disease, type 2 diabetes, high blood pressure, and certain types of cancer.
Unfortunately, for most Americans, whole-grain intake remains low. The Dietary Guidelines for Americans suggest that at least half of your grain choices should be whole grains. So if you eat six ounces of grains in a day, at least three of those should be whole grains. However, most Americans get one serving of whole grains and five servings of refined grains daily.
What Was Studied?
This prospective study used data collected from the National Heart, Lung, and Blood Institute Framingham Heart Study Offspring Cohort. Medical data and dietary information was collected for 3,121 participants.
Researchers assessed that data to see if there were associations between whole vs. refined grain consumption and changes in waist circumference, cholesterol, triglyceride, blood sugar, and blood pressure levels over time.
What Did the Study Find?
“We found that among middle- to older-aged adults, those who consumed 3 or more servings of whole grains daily had smaller increases in waist size, blood pressure, and blood sugar levels over time compared to those who ate less than ½ serving of whole grain daily,” says Dr. Caleigh Sawicki, Ph.D., MPH, a researcher at the Friedman School of Nutrition Science and Policy at Tufts University and one of the authors of this study.
Sawicki explains that those who consumed 3 or more servings of whole grains daily also had greater declines in triglyceride levels, which is a blood lipid level linked to greater cardiovascular disease risk.
“However,” says Sawicki, “these changes were in part attributed to the lower gains in waist circumference – suggesting that the improvements in triglycerides observed in the higher whole grain consumers is likely due to less gains in belly fat.”
Interestingly, the opposite associations were seen in people eating more refined grains. Study participants eating four or more servings of refined grains daily had a greater increase in waist circumference.
Based on the study’s findings, Sawicki recommends that people try to increase whole grain intake by replacing some of the refined grain foods in the diet with whole grain alternatives, such as switching from white bread to whole grain bread, and from white rice to brown rice.
“There is nothing wrong in eating refined grains occasionally,” adds Chopra. “Balancing whole grain and refined grain intake is key.”
Caleigh Sawicki, PhD, MPH
— Caleigh Sawicki, PhD, MPH
Benefits of Whole Grains
Whole grains are often touted as a nutritious choice, but what makes them so healthy, and why do they help lower blood pressure, triglyceride and blood sugar levels?
While the exact mechanism isn’t known, Nicola M. McKeown, Ph.D, an Associate Professor at the Friedman School of Nutrition Science and Policy, Tufts University and one of the study’s researchers, explains that the benefits may be related to the fiber in whole grains.
“Dietary fiber can slow digestion and help us to feel full so that we might eat a little less—which over time helps with maintaining body weight or preventing weight gain,” says McKeown. “Other health benefits of incorporating more whole grains is that it can help to reduce post-meal blood sugar spikes – which may help ward off food cravings.”
In addition to fiber, McKeown adds that whole grains provide:
- Magnesium and potassium, which may help with maintaining healthy blood sugar levels and blood pressure.
- Antioxidants like vitamin E, which help protect our cell membranes from damage by harmful molecules (free radicals).
- Phytochemicals that may act alone or in synergy with other nutrients to help maintain our health as we age.
Nicola M. McKeown, PhD
— Nicola M. McKeown, PhD
And If You Still Think “Carbs Are Bad…”
Low-carb diets work well for some people, but whole grains can certainly be part of a nutritious and varied diet too.
“For the majority of people, avoiding all carbohydrates is not sustainable or healthy,” says McKeown. “Some people remove grains from their diets in hopes of losing weight, but skipping out on whole grains means you would be missing an important source of fiber, B vitamins, vitamin E, magnesium, potassium, and numerous polyphenols—all of which have important impacts on our health.”
McKeown reminds us that the nutritional quality of all carbohydrates is not the same, and says we should place more emphasis on the quality of the carbohydrates we consume. That means less sugar and fewer refined carbs like white bread, and more whole grains, vegetables, and fruit.
What This Means For You:
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