Many diets advocate reducing or even eliminating carbohydrates of any kind, a trend that likely started because Americans tend to overeat refined carbs (think white bread, rice, and pasta). What those diets don’t take into consideration, however, is that the carbohydrate category also includes whole grains, which provide essential nutrients and act as the foundation of a healthy diet.
Whole grains are packed with antioxidants, B vitamins, and fiber, and because there are so many different kinds, from amaranth to wild rice, they’re also incredibly versatile. This guide will tell you what you need to know about whole grains, including how to get more into your diet.
Whole grains have three parts: the bran (the hard outer shell and source of fiber), endosperm (the starchy carbohydrate middle layer), and the germ (nutrient-packed core), according to the Whole Grains Council. The outer and innermost layers of a whole grain contain key nutrients. The bran is rich in antioxidants, B vitamins, and fiber; the germ, which is the “embryo” of the grain, contains protein and healthy fats.
When grains are refined, which is usually done to make products last longer or have a more appealing texture or flavor, many of those nutrients are stripped away. Refined grains include things like white flour and rice.
Common whole grains include whole-wheat flour, wheat berry, bulgur, oatmeal, whole-grain cornmeal, quinoa, and brown rice. Because there are so many different types of whole grains, it can be challenging to keep track of how many servings you are eating or know how much you “should” be eating. The exact serving size recommendation for whole grains depends on the individual, says Clara Nosek, a registered dietitian-nutritionist based in California. “The general recommendation for whole grains is to ensure at least half the grains you eat are whole grains,” she says. “As a general recommendation, a cupped hand or fist-size serving is a great place to start.”
The USDA recommends between 6 and 10 ounces (oz) of grains per day for adults, with at least 3 to 5 oz being whole grains. What that looks like serving-size-wise varies. For bread, one slice is typically about one ounce. For things like oatmeal, rice, and quinoa, one ounce is about half a cup (cooked).
Whole grains are a good source of complex carbohydrates, which our bodies need, and they are also packed with vitamins, including thiamine, niacin, and folate, plus minerals such as iron, magnesium, and selenium, says the USDA.
Thiamine (also known as B1) The water-soluble B vitamin plays a crucial part in how our cells metabolize energy, which then affects the overall growth and development of cells, according to the National Institutes of Health (NIH). Adults need about 1.2 milligrams (mg) of thiamine per day.
Niacin (also known as B3) Niacin is also important for cell development and function, and for turning food into energy, per the NIH. Adults need about 14 to 16 mg of niacin per day.
Folate Our bodies need folate to create genetic material and divide cells, which is why it is so important for those who are pregnant to make sure they are getting the right amount of folate in their diets (around 600 micrograms [mcg] daily). Nonpregnant adults need about 400 mcg daily of folate, per the NIH.
Iron Iron is a mineral that our bodies need to produce hemoglobin in the blood, myoglobin, and some hormones. Iron recommendations vary significantly by sex and age, as detailed by this comprehensive list from the NIH.
Magnesium Magnesium is vital to several bodily functions, including regulating muscle and nerve function, blood sugar levels, and blood pressure and making protein, bone, and DNA, per the NIH. Adults need about 310 to 420 mg per day, with men needing the higher end of this range.
Selenium Selenium is a mineral necessary for reproduction, thyroid gland function, DNA production, and protecting the body from damage caused by free radicals. Adults need about 55 mcg of selenium daily, per the NIH.
Dietary fiber Whole grains are a recommended source of dietary fiber, a nutrient most Americans don’t get enough of, according to the MedlinePlus. Fiber is the indigestible part of plants and can help fill you up so you eat less, which aids weight loss. It can also help prevent constipation. “Some types of fiber act as prebiotics, which means they feed the beneficial gut bacteria,” says Nosek. A study published in the journal Nutrients cited whole grain cereal to have prebiotic effects in the gut.
“Refining is a process where they remove the bran and nutrients in it, to create a flour that is easier to cook,” says Dalina Soto, RD, the founder of Nutritiously Yours and Your Latina Nutritionist. Milling technology invented in the late 19th century allowed for easy removal of the germ, whose fat content can cause products to spoil faster, and bran, which can be tough to cook and chew. Although eating refined grains such as white breads, rice, pastas, and pastries can be fine in moderation, the refining process strips away “more than half of wheat’s B vitamins, 90 percent of the vitamin E, and virtually all of the fiber,” according to the Harvard T.H. Chan School of Public Health.
Once refined grains became popular, though, so did nutritional deficiencies that led to diseases such as pellagra and beriberi. This caused many governments around the world to require enriching refined grains with some of the vitamins and minerals lost in processing, including B vitamins, iron, and folate, according to the Whole Grains Council.
Regularly consuming whole grains has been linked to a number of potential health benefits. Here are some of the conditions whole grains have been shown to improve.
Inflammation-related diseases Whole grains have been linked to lower rates of systemic cellular inflammation, according to a meta–analysis published in Medicine in October 2018. A review published in January 2022 in Nutrients had similar findings, and attributed these benefits to the fiber, phytochemicals, and metabolites in whole grains. These substances may directly affect inflammatory markers such as C-reactive proteins, as well as indirectly affect them via the microbiome, by acting as prebiotics, or fuel for the beneficial microbes in the human gut.
Cardiovascular disease and cholesterol The substitution of whole grains for refined grains substantially lowers total cholesterol, low-density lipoprotein (LDL, or "bad") cholesterol, and triglycerides, according to a meta-analysis published in the American Journal of Clinical Nutrition. Whole oats were shown to be the most effective at lowering cholesterol. Additionally, research published in June 2022 in BMC Medicine found that diets that are generally high in whole grains, as well as high intakes of specific whole grains (with the exception of popcorn) were significantly associated with a lower risk of coronary heart disease.
Type 2 diabetes Eating at least two servings of whole grains per day instead of refined grains could improve insulin sensitivity and glucose metabolism, prevent blood sugar spikes, and lower the risk of type 2 diabetes, according to a review published July 8, 2020, in the BMJ of three long-term diabetes studies that followed up with participants from 1984 to 2016. Refined grains have a higher glycemic index and less fiber, meaning they are more likely to affect blood sugar.
Certain cancers A meta-analysis of seven scientific studies on the connection between whole-grain intake and cancer risk, published December 7, 2020, in the journal Nutrients, found that whole-grain intake was associated with up to a 12 percent lower risk of colorectal, colon, gastric, pancreatic, and esophageal cancers.
Obesity Another meta-analysis, published in Nutrients in June 2019, found that whole-grain intake was associated with a lower risk of weight gain and had an inverse relationship to BMI (body mass index). Both Nosek and Soto agreed that grains have been unfairly demonized by the diet industry, and that grains are absolutely part of healthy eating. “In my experience, limiting carbohydrates is a lazy catchall for ‘healthy eating,’ a quick fix for speedy weight loss,” says Nosek. Soto blames diet culture and fatphobia for the trend away from eating carbs, saying that carbs are the body’s primary source of energy.
There are many types of whole grains to choose from, so it’s easy to get your fill. According to the U.S. Department of Agriculture, they include:
Whole-wheat varieties of:
One of the easiest ways to identify a product as whole grain is to look for the Whole Grains Council stamp on the packaging. The Whole Grains Council marks thousands of products as either 100 percent, 50 percent or “basic” (less than 50 percent) whole grain, and you can look up specific products on the council's website.
Otherwise, says Soto, “The ingredient list will say whole grain before the name, and it should be one of the first ingredients, if not the first.”
Whole-grain products will typically spoil faster than refined or enriched products, but because each type of whole grain has a different fat content, some will spoil quicker than others. Intact whole grains such as brown rice or quinoa should keep for up to six months in an airtight container in the pantry or one year in the freezer, according to the Whole Grains Council. Whole-grain flour will stay fresh for one to three months in the pantry and six months in the freezer. You could also store your grains such as whole grain bread in the refrigerator if you are worried about it going bad before you are able to eat it.
Want to get more whole grains in your day? Get inspired by these RD-approved recipes.
Despite the explosion in popularity of low-carb diets, it's important to remember that whole grains provide crucial vitamins, minerals, and fiber that our bodies need. Four to five daily servings of grains in their whole form — bran, endosperm, and germ intact — will improve your cholesterol, lower your risk of heart disease and diabetes, and help you stay fuller longer.
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