Study Suggests Eating Whole Grains May Affect Cardiovascular Health
Eating whole grains has been linked to an abundance of positive health outcomes, including prebiotic gut effects, healthier body weight, and prevention of major diseases like type 2 diabetes and certain cancers (colorectal, pancreatic, and gastric). If that wasn't enough, a recent study just gave us one more reason to love whole grains: your heart health.
I got to chat with the lead study author, to glean firsthand insights into her latest research investigation. But first, some whole-grain basics to get us all on the same page.
Whole grains vs. refined grains.
Whole grains contain the entirety of the grain kernel—the bran, germ, and endosperm. Along with energy (calories) from carbohydrate, protein, and fat, you'll find additional nutritional bioactives in whole grains like fiber, an array of micronutrients, and even phytochemicals.
For example, one large whole wheat pita delivers about 220 calories, 47 grams of carbohydrate, 8 grams of protein, 1.5 grams of fat (mostly unsaturated and polyunsaturated), 5 grams of fiber, and 18 unique vitamins and minerals.
In contrast, refined grains are processed foods, made via a milling process that takes out the bran and germ. This just leaves the endosperm, which produces a starchy grain with finer texture and longer shelf life. The trade-off is a loss of fiber and most micronutrients, which is why many refined grain products are enriched with iron and some B vitamins (i.e., they're added back in).
Americans are getting a failing grade for whole-grain intake.
Data-driven results on the diet quality of Americans are a bit of a downer (sorry). Our nutrition report card has a failing grade, with a current Health Eating Index score of 59 out of 100 for Americans over the age of 2. For whole-grain intake specifically, Americans score a 3 out of 10. We are doing a slightly better job of practicing moderation with refined-grain intake, though, with a grade of 6.4 out of 10.
What did the new study on whole grains find?
The findings from a recent study published in the Journal of the Academy of Nutrition and Dietetics give us more motivation to improve whole-grain intake: cardiovascular disease (CVD). The investigation was led by Skye Marshall, Ph.D., APD, who is scientific and education director at Nutrition Research Australia and assistant professor of nutrition and dietetics at Bond University in Queensland, Australia. This robustly designed systematic review and meta-analysis of randomized controlled trials (RCT) examined the effect of whole grains (vs. refined grains or placebo) on CVD risk factors in adults.
Marshall explains the impetus for her study, sharing that, "Although there is really convincing observational evidence for the effect of whole grains on improved cardiovascular health, we do need interventional evidence to establish a cause-and-effect relationship." (RCT studies are the cream of the crop for determining causality/effect. Meta-analyzing multiple RCTs for a holistic perspective is even better.)
In all, 22 relevant RCTs, which lasted two to 16 weeks, were meta-analyzed by the researchers. Most included a mixed whole-grain intervention in healthy adults, while others had CVD risk factors. Here are the significant cardiometabolic effects the analysis indicated:
- Whole-grain oats reduced total and LDL cholesterol levels.
- Whole-grain rice decreased triglycerides.
- All types of whole grains improved hemoglobin A1c (HbA1c is a measure of blood sugar control) and C-reactive protein, a biomarker of inflammation that's tied to CVD risk.
When you combine those findings, it suggests that in adults, swapping out refined grains with whole grains may improve major CVD risk factors—lipids, blood glucose, and inflammation. The potential public health impact is massive, as heart disease is the No. 1 cause of death in Australia and the United States. Marshall elaborates on the significance of the study's findings, sharing that "In the long term, your cardiovascular health may be improved if you regularly choose whole-grain foods instead of refined (i.e., 'white' bread, rice, pasta, etc.)."
But, practicing moderation in nutrition and life is also important. Marshall shares that, "eating some refined grains is OK. You shouldn't feel guilt while eating refined grains, especially foods important to your culture and social life."
Marshall and I then chatted about the popularity of low-carb diets and how carbs have gotten a bad rap in recent years in the U.S. She said the same trends have occurred in Australia and warns people of "the negative psychological effect of restrictive eating." She adds that the anti-carb camp "is being balanced by a counterculture of people really enjoying their carbs. A focus on healthy eating patterns can help, like the Mediterranean diet, which allows all food groups including those high in carbs." In fact the Mediterranean diet, which incorporates whole grains and other carb sources like fruits, vegetables, and legumes, is impressively linked to reductions in coronary heart disease, ischemic stroke, and total CVD.
While there's always room for more RCT research on whole grains for the prevention and treatment of CVD, this latest research supports the idea that grains can be an important part of the heart-health equation. However, for anyone with CVD diagnoses, Marshall says, "Overall lifestyle and diet is really important but should not replace traditional medical treatment."
Tips for eating more whole grains.
With the benefits of whole grains mounting, it's a wonder more people don't eat them. "I think it's the taste!" says Marshall. "Most people choosing whole grains do so because they are aware of the superior nutrient profile. But whole grains have so much flavor and texture, which can really improve a meal. Perhaps it's a learned appreciation like coffee, chili, or beer."
As for the top whole grains Marshall recommends for cardiovascular health: "It does look like whole rolled oats and brown rice have the best evidence, currently, but the overall diet is what counts. Choosing whole grains of any type regularly is what matters," she says. "For example, I eat whole-grain oats and wheat two or three times a day but rarely eat rice of any kind. Someone could be the opposite, and that's OK too."
To help you get more grains in your diet, I've rounded up a few options to whet your appetite. For folks with celiac disease or gluten intolerance, there are some gluten-free whole grains for you, too:
- Eat less of this (refined grains): white flour, white bread, white rice, and de-germed cornmeal, which are found in many breads, cereals, crackers, desserts, and pastries.
- Eat more of this (whole grains): barley, rye, triticale, wheat (including varieties like spelt, emmer, farro, einkorn, Kamut®, durum, and forms like bulgur, cracked wheat, and wheat berries). And these gluten-free options: amaranth, buckwheat, corn (including whole cornmeal, blue corn, and popcorn), Job's tears (aka pearl barley, hato mugi), millet, Montina (Indian rice grass), oats, quinoa, rice (brown, red, purple, and black rice), sorghum (also called milo), teff, and wild rice.
When shopping for whole grains, some products will have a whole-grain stamp to help you quickly identify them. When in doubt, flip the product over and check the ingredient list. If the first ingredient mentions the word "whole," that's a good sign that you're buying a whole grain.
For individuals avoiding gluten, steer clear of all varieties of wheat, barley, rye, and triticale. These all contain the gluten protein. Oats are gluten-free, but be sure to check the label for pure, uncontaminated oats.
This recent study demonstrates benefits of whole grains on cardiovascular risk factors, adding to a large body of evidence supporting whole-grain intake for health and wellness. Americans are currently underconsuming whole grains, so there's room for improvement. Replacing refined grains in your diet with whole grains is a smart, evidence-based nutrition strategy. A wonderfully colorful diversity of whole-grain foods exists (including many gluten-free options), so this nutrient-dense part of your meal and lifestyle never has to get boring.
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