New research on whole grains and health

By Erin Cazel, guest contributor

This article was originally published in July 2022

Variety of different grains

Whole grains are widely associated with decreased risk for several chronic diseases. The mechanisms behind those health benefits aren’t fully understood, which has stalled consumers at a crossroads of conflicting recommendations: How much and how often should whole grains be eaten? What kinds of whole grains are best to consume? Is there an ideal way to prepare whole grains? 

New evidence now provides some clearer direction, showing that the benefits of consuming whole grains are the result of an intricate dance of interactions between fiber, the gut microbiome (trillions of diverse bacteria living within the human digestive tract), and a group of bioactive compounds in grains called phytochemicals. 

Partners in the dance

Many chronic diseases, including cardiovascular disease, hypertension and diabetes, are at least partially connected to an imbalance of healthy and unhealthy bacteria in the gut microbiome. This can lead to oxidative stress (an imbalance between antioxidants and unstable molecules called free radicals) and a related increase in harmful inflammation. 

Fiber, a component of whole grains, has received a lot of credit for the health benefits of the grains. While it might be tempting to reach for fiber supplements for an easy way to consume the recommended daily amounts of fiber (see below), optimal benefits can be derived by consuming whole foods. This allows fiber to function in tandem with other beneficial compounds, such as phytochemicals.

There are thousands of different phytochemicals. These compounds are produced by plants (“phyto,” derived from ancient Greek, means “plant”), and provide vegetables, fruits, whole grains, legumes, spices, and herbs with their characteristic flavors, colors, and aromas. They also play a role in plant growth and defense from infection or predation. Phytochemicals are characterized as bioactive because of their potential capacity to impact human health, and many scientific studies seek to uncover these effects. Research shows associations between the phytochemicals in whole grains and antioxidant activity, reductions in inflammation, strengthened immunity and improved microbiome health. The ripple effects of these systemic changes are widespread, improving digestion, metabolism and mental and emotional health. 

Complexity and complications

While these are exciting prospects, the picture is complicated. First, phytochemicals are often bound in the fibers of the bran layer of whole grains, the outer skin of the edible grain kernel. This limits the degree to which the phytochemicals can be absorbed in our bodies. It also makes it difficult to distinguish between the effects of fiber and phytochemicals. Second, unlike macronutrients (carbohydrates, proteins, fats) and micronutrients (vitamins and minerals), fibers and phytochemicals are not directly incorporated into body tissues. Instead, their effects are often indirect. For example, phytochemicals can turn on or off the expression of different genes, as well as activate elements within the immune system. 

Finally, fibers and phytochemicals can be metabolized by the gut microbiota. This both nourishes healthy gut bacteria and produces byproducts that are themselves health-promoting. The microbiome is incredibly dynamic: the types and quantity of bacteria change in response to foods consumed. This means that an individual’s microbial profile is unique and evolves over time, making it difficult to measure a specific health impact, and also accounting for the wide range in individual response. 

There’s more. The composition of fibers and phytochemicals within a whole grain varies not only between species of grain, but also between varieties within a species. It is even influenced by the geographical location and season in which the crop is grown. Soaking, sprouting, and fermenting whole grains separates phytochemicals from fibers, increasing their availability and absorption. While these are often suggested as preparation techniques, current research reinforces the health benefits of whole grain consumption with a variety of preparation techniques. While there are benefits to releasing the phytochemicals from the fibers, it is still beneficial to eat whole grains even without soaking, sprouting or fermenting.

As studies continue, specific compounds are likely to enter the research and popular-media spotlight. It’s unlikely, though, to acquire extra benefits from any solitary chemical. Because the composition of a whole grain is vast and complex, health benefits are likely due to the synergy of many different compounds rather than a single one in isolation. The best way to optimize health benefits is to incorporate a wide variety of whole grains into daily food patterns. Try including a whole grain with every meal and experimenting with types that are new to you. Pay attention to how your body feels when eating various whole grains. Remember: you and your microbiome are unique, so listen to your gut.


Erin Cazel is pursuing a Master’s in Nutrition at Bastyr University. Radical hospitality is Erin’s life passion—she loves gathering community around a table filled with food and conversation, and cares deeply about using foods to nurture the body, heart and mind. 

A pioneer in natural medicine, Bastyr University is a nonprofit, private university that is at the forefront of developing leaders in natural health arts and sciences for the 21st century. Bastyr offers graduate and undergraduate degrees in science-based natural medicine that integrates mind, body, spirit and nature. The University is also a leader in conducting cutting-edge research in complementary and alternative medicine and in offering affordable natural healthcare services in its local communities. 

Whole grains and fiber

The U.S. Department of Agriculture (USDA) recommends most adults consume 25 to 38 grams of fiber per day. Most Americans consume less than half that amount, from 10 to 15 grams per day.

Whole grains are an excellent source of fiber, with amounts ranging from a half gram of fiber to 3 grams of fiber per serving, according to the nonprofit Whole Grains Council. (Processed grains have typically had both the nutritious bran and germ layers of their kernels removed, including much of the fiber.) Higher-fiber sources of whole grains include barley, brown rice, whole wheat, oats, quinoa, amaranth, teff, sorghum and millet. Bulk bins are typically a budget way to stock up on many of these grains.

Also in this issue

Community Voices: A Q&A with FEEST

PCC partner FEEST is working with youth leaders on “Making Justice Irresistibly Delicious.”

The Cherokee Purple puzzle: Should we rename famous seeds?

While seed names can be a beautiful connection to identity, culture, worldview and history, seed growers are grappling with old names that are derogatory or incorrect.

News bites

California’s green grid • World food prize • Culinary program saved • Soil health program • Black farmers and wealth • Bird-friendly beef? • Cropland control • Plant fungus decoded • Energy-efficient lights • Microplastics concerns • Sustainable Yakima • Seed libraries sprout • People’s gardens • Antibiotics in beef • Insects in decline • Recycling rates drop