The Amazing, Little-Known Benefits of Dietary Fiber

Fiber Regulates Your Immune System

Research in Australia demonstrates that fiber triggers an integral part of the immune system that fights off viruses -- including the flu. The study at Monash University found fiber feeds probiotic bacteria in your digestive tract, increasing the production of short-chain fatty acids. These fatty acids play two critical roles in your overall immune health -- keeping harmful excessive inflammation in the lungs from getting out of control and activating T cells that can efficiently zap an invading flu virus.¹ "We typically find that a certain treatment turns our immune system either on or off," says researcher Benjamin Marsland. "What surprised us was that dietary fiber was selectively turning off part of our immune system (the harmful inflammatory part) while turning on another, completely unrelated (virus killing) part of our immune system." And there’s more...

Fiber Fights Food-Borne Pathogens

At the same time, research in Japan shows that fiber can protect against food poisoning, especially from Salmonella bacteria – a common culprit in food-borne illness. The study shows another positive interaction between those short-chain fatty acids in your digestive tract and your immune system. The fatty acids link up to proteins that are part of the inflammasome complex – a protein structure that alerts the immune system to Salmonella invasion and other pathogens. And the alert leads immune cells to destroy illness-causing microbes quickly.²

Fiber Helps Heart Health

Research has established solid evidence that dietary fiber is crucial for better heart health. For example, a Norwegian study indicates that for people suffering from heart failure, extra fiber is associated with a reduced risk of death and can even eliminate the need for a heart transplant. According to these findings, consuming extra fiber encourages the growth of a more diverse and healthier collection of probiotic bacteria in the digestive tract that keep the heart functioning at a higher level. These researchers think that if you have a faltering heart, are overeating meat – more than about two or three times a week – and have too little fiber, this may increase your need for a heart transplant.³ "Our findings suggest that the altered microbiota (probiotic bacteria) composition (in the digestive tract) found in patients with chronic heart failure might be connected to low fiber intake," warns researcher Cristiane Mayerhofer. Added to that analysis, a review study in New Zealand shows that when you eat large amounts of high-fiber foods, you can drop your risk of coronary heart disease and stroke, as well as type 2 diabetes, by 16 to 24 percent. This review looked at the results of 185 studies and 58 clinical trials.⁴ The researchers concluded, "The benefits of fiber are supported by over 100 years of research into its chemistry, physical properties, physiology, and metabolic effects." This isn’t surprising. Fiber helps control blood sugar levels. In people with diabetes, fiber — particularly soluble fiber — can slow the absorption of sugar. Also, a healthy diet with insoluble fiber may reduce the risk of developing type 2 diabetes.

Fiber Helps You Lose Weight, Fight Colon Cancer

High-fiber foods are a critical part of any healthy weight loss regimen. They’re more filling than low-fiber foods, so you’re less likely to overeat. What’s more, you won’t become hungry again as quickly. High-fiber foods also contain fewer calories by volume when compared to other foods. “High fiber foods may help reduce your overall calorie intake and help you maintain a healthy weight, which is vital to reducing cancer risk,” says Erma Levy, research dietitian in Behavioral Science at MD Anderson Cancer Center.⁵ Dr. Denis Burkitt, an Irish surgeon, was one of the first to make the connection between a high-fiber diet and low rates of cancer. In the 1950s Dr. Burkitt traveled to Africa on a missionary trip to help improve the people's health. While he found numerous health problems, what he didn’t see was colorectal cancer. While Americans and other Western populations had a lot of colon problems, poor digestion, irregularity, and high rates of colon cancer, the Africans he studied had an astonishingly low rate of colon problems and cancers. Dr. Burkitt realized that Africans ate large amounts of beans, corn, and other high-fiber foods in their original state. Americans, by contrast, were mainly eating processed foods.⁶ Mary Daly, M.D., chair of the department of clinical genetics at Fox Chase Cancer Center in Philadelphia, says because fiber passes quickly through the colon, it perhaps “flushes out cancer-causing compounds.” It may even “change these compounds, making them less harmful.” That being said, Dr. Daly and her counterparts agree that there hasn’t been absolute scientific evidence that fiber prevents colon cancer. However, in that large research review out of New Zealand, I mentioned earlier, a high-fiber diet lowered the risk of colorectal cancer by 16 to 24 percent. In addition, studies suggest that increasing your dietary fiber intake — especially cereal fiber (such as bran, brown rice, and whole grains) — is associated with a reduced risk of dying from all cancers.

Increasing Fiber in Your Diet

Fiber is commonly classified as soluble, meaning it dissolves in water, or insoluble, meaning it doesn't. Soluble fiber is found in oats, peas, beans, apples, citrus fruits, carrots, barley, and psyllium. Insoluble fiber is found in whole wheat flour, wheat bran, nuts, beans, and vegetables such as cauliflower, green beans, and potatoes. To reap the most significant health benefit, eat a wide variety of high-fiber foods, including plenty of fruits and vegetables, according to the Mayo Clinic.⁷