Whole grains provide a host of potential benefits, from reduced risk of diabetes and heart disease to improved digestive health and appetite control. Now two clinical trials from Tufts University, published recently in the American Journal of Clinical Nutrition and reported in Berkeley University Wellness Letter, have shown that substituting whole grains for refined grains, even for a short period, leads to "modest" improvements in the balance of microbes in the intestines (gut microbiome) along with improvements in aspects of the immune response and energy metabolism.
It's important to note that both studies are small. Both studies involved the same 81 healthy adults (ages 40 to 65), half of whom consumed a diet rich in whole grains (whole wheat, oats, and brown rice) for six weeks, while the rest ate refined grains. Other than the different forms of grains, the diets were virtually the same. All foods were provided in order to ensure that the diets kept body weight stable; participants were weighed three times a week and their diets were adjusted if they gained or lost weight. The whole grains provided about twice as much fiber (mostly insoluble fiber) as well as some extra nutrients and other potentially beneficial compounds.
In the first study, researchers assessed the effect of whole grains on the microbiome by analyzing the participants' stool for its bacterial content and concentration of fats. Previous research has shown that whole grains increase the variety of the microbiome and boost production of short-chain fatty acids, both of which are linked to immune function and digestive health. Along these lines, the whole-grain group in the new study had an increase in bacteria that produce short-chain fatty acids and a decrease in pro-inflammatory bacteria, among other positive changes, compared to those eating refined grains. What's more, blood samples from the whole-grain group showed small improvements in several markers of a healthy immune response.
The second study focused on changes in energy metabolism that could affect weight regulation. It found that whole grain consumption led to decreased calorie retention during digestion (as measured by calories in stool) and slightly higher resting metabolic rate -- resulting in a net daily energy loss of 92 calories per day, on average, compared to the refined-grain diet. Self-reported hunger and fullness were not statistically different between the two groups. The additional fecal energy losses were due to the extra fiber's effect on the digestion of other food calories, the researchers suggested.
The Dietary Guidelines for Americans recommend that at least half of your daily grain intake be whole grains. That means at least three servings if you eat a 2,000-calorie-a-day diet; a serving is one slice of whole-wheat bread or half a cup of oatmeal or brown rice, for example.
And while these studies are small, the results are worth noting. Whole grains can not only benefit your gut microbes, they improve overall health. The tricky part can be in reading a label to make sure what you're purchasing is truly a whole grain. A package of dark brown bread touting "made with whole grains" may contain mostly refined white flour. And a box of pasta labeled "wheat" or "semolina" can contain zero whole-grain ingredients. Look for the words "100% whole grain" on the package, or the first ingredient of "whole wheat" or "whole" followed by the name of another grain (such as barley or corn), then you can be assured, it's mostly or totally a whole-grain food.
RECIPE
Here's a twist on the usual baked beans for your next family picnic. These tangy baked beans combine peaches, adobo sauce and a little bourbon for big flavor. The recipe is from Cooking Light magazine. As an added bonus, you can use your slow cooker and keep the heat down in your kitchen.
Slow Cooker Bourbon Peach Baked Beans
3 center-cut bacon slices, chopped
Cooking spray
2 (15-ounce) cans unsalted cannellini beans, drained and rinsed
2 (15-ounce) cans unsalted pinto beans, drained and rinsed
2 ripe peaches peeled and finely diced (about 2 cups)
2 garlic cloves, minced
1/2-cup ketchup
1/2-cup bourbon
1/4-cup pure maple syrup
2 tablespoons balsamic vinegar
1 tablespoon Dijon mustard
2 teaspoons chopped canned chipotle chiles in adobo sauce
2 teaspoons chili powder
1 teaspoon smoked paprika
1/4-teaspoon salt
1/4-teaspoon freshly ground pepper
Heat a large nonstick skillet over medium-high. Add bacon and cook, stirring occasionally, until crisp, 4 to 5 minutes. Remove bacon from skillet. Coat inside of a 4-quart slow cooker with cooking spray. Add bacon, beans and remaining ingredients. Stir well. Cover and cook on Low 4 to 6 hours. Keep covered until beans are ready to serve. Serves 12 (serving size: about 1/2 cup)
Per serving: 181 calories, 7 g protein, 30 g carbohydrate, 1 g fat, 1 mg cholesterol, 6 g fiber, 7 g sugars, 267 mg sodium
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