As we age, our brain cells become inflamed and begin to produce chemicals known to impair cognitive and motor function. That's one explanation for why memory fades and other brain functions decline during old age.
Scientists at the University of Illinois may have a remedy: more dietary fiber. Dietary fiber promotes the growth of good bacteria in the gut. When those good bacteria digest fiber, they produce short-chain fatty acids, such as butyrate, as byproducts.
"Butyrate is of interest because it has been shown to have anti-inflammatory properties on microglia and improve memory in mice when administered pharmacologically," says Rodney Johnson, a professor and the head of the Department of Animal Sciences at the University of Illinois, and author of the study, published in the journal Frontiers in Immunology.
The new study reveals that butyrate in old mice inhibits the production of damaging chemicals by inflamed microglia. One of those chemicals is interleukin 1B, which has been associated with Alzheimer's disease in humans.
Johnson and his team looked at whether the same effects could be obtained simply by feeding the mice more fiber, because gut bacteria naturally convert fiber into butyrate.
"People are not likely to consume sodium butyrate directly, due to its noxious odor," Johnson said. "A practical way to get elevated butyrate is to consume a diet high in soluble fiber."
"We know that diet has a major influence on the composition and function of microbes in the gut and that diets high in fiber benefit good microbes, while diets high in fat and protein can have a negative influence on microbial composition and function. Diet, through altering gut microbes, is one way in which it affects disease," says Jeff Woods, a professor in the Department of Kinesiology and Community Health at the University of Illinois, and co-author on the study.
Butyrate derived from dietary fiber should have the same benefits in the brain as the drug form, but no one had tested it before. The researchers fed low- and high-fiber diets to groups of young and old mice and then measured the levels of butyrate and other SCFAs in the blood, as well as inflammatory chemicals in the intestine.
"The high-fiber diet elevated butyrate and other SCFAs in the blood both for young and old mice. But only the old mice showed intestinal inflammation on the low-fiber diet," Johnson says. "It's interesting that young adults didn't have that inflammatory response on the same diet. It clearly highlights the vulnerability of being old."
The next step was looking at signs of inflammation in the brain. The researchers examined about 50 unique genes in microglia and found that the high-fiber diet reduced the inflammatory profile in aged animals.
Although the study was conducted in mice, Johnson is comfortable extending his findings to humans, if only in a general sense. "What you eat matters. We know that older adults consume 40 percent less dietary fiber than is recommended. Not getting enough fiber could have negative consequences for things you don't even think about, such as connections to brain health and inflammation in general."
Q and A
Q: Is oil safe to cook with?
A: Oil is safe to cook with under usual conditions. The primary concern some people have is oxidation, a natural process that occurs when one molecule gives up an electron to another as part of a chemical reaction. The process creates free radicals, which can cause damage that could increase risk for problems such as heart attack, stroke and cancer. Oils and oily foods (like nuts and whole grains) can oxidize over time, even without cooking. Exposure to light, heat and air speed up this process. Keep oils in a cool, dark place and store nuts, whole grain flours and fish, nut and seed oils in the refrigerator to keep them fresh longer. Repeatedly heated cooking oil has been found to have more signs of oxidation, so it's best not to reuse cooking oil. To counteract free radicals, whether they are formed by normal metabolism in the body or in oils, eat plenty of plant foods. Fruits, vegetables and other plants have antioxidants that can counteract free radicals in the body.
Information courtesy of Tufts University Health & Nutrition Letter.
Chili and fall just seem to go together. Here's a healthier version using ground turkey. Using traditional kidney beans and black beans boosts the fiber. Using no-salt-added canned beans and tomatoes lowers the sodium. This recipe is from Hy-Vee's Balance magazine.
Nonstick cooking spray
1 1/2 pounds 99 percent-lean ground turkey
1 cup chopped onion
1 cup chopped red bell pepper
1 cup chopped green pepper
1 packet chili seasoning mix
1 tablespoon no-salt-added tomato paste
1 (28-ounce) can no-salt-added crushed tomatoes, undrained
1 (15-ounce) can no-salt-added dark red kidney beans, rinsed and drained
1 (15-ounce) can no-salt-added black beans, rinsed and drained
1 (8-ounce) can no-salt-added tomato sauce
Spray stockpot with nonstick cooking spray. Place turkey, onions and bell peppers in stockpot. Cook and stir over medium heat until turkey is browned and vegetables are tender. Add chili seasoning mix and tomato paste. Cook and stir for 1 minute. Transfer turkey mixture to a 3 1/2- to 4-quart slow cooker. Add crushed tomatoes, beans and tomato sauce. Stir to combine. Cover and cook on low heat for 6 hours or on high heat for 3 hours. Serves 8.
Per serving: 190 calories, 24 grams protein, 20 grams carbohydrates, 0.5 grams fat, 45 milligrams cholesterol, 5 grams fiber, 6 grams sugar and 220 milligrams sodium.
Charlyn Fargo is a registered dietitian at Hy-Vee in Springfield, Illinois, and the media representative for the Illinois Academy of Nutrition and Dietetics. For comments or questions, contact her at [email protected] or follow her on Twitter @NutritionRd. To find out more about Charlyn Fargo and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate website at www.creators.com.