Why Fiber Can Help You Live Longer

By Cliona Byrnes, RD

We’ve likely all heard the advice to eat more whole grains, choose whole wheat bread over white to increase our fiber intake – but why? Fiber is a non-digestible form of carbohydrate that occurs naturally in plant foods and broadly consists of soluble fibers, found in oats, beans and the flesh of fruits and vegetables and insoluble fiber (or “roughage”), found in skins of fruits and vegetables and high fiber breakfast cereals. All forms can support a healthy gut, steady blood glucose levels, weight maintenance, and the prevention of chronic disease. Indeed, a 2019 review published in the Lancet medical journal highlighted that people with higher intakes of fiber are more likely to live longer, with a 15-30% reduction in all-cause and cardiovascular related mortality in those with the highest fiber intakes compared to those with the lowest. Interestingly, for every additional 8 grams of dietary fiber consumed daily, the incidence of heart disease decreased by 19%, the risk of developing type 2 diabetes decreased by 15% and the incidence of colorectal cancer was reduced by 8%.

Let’s take a closer look at some of the key benefits of following a high-fiber diet.

1. Good for Your Gut

There is increasing awareness of the importance of a healthy gut and microbiome for everything from optimizing digestion, supporting the immune system and protection against chronic disease. While both soluble and insoluble forms of fiber pass through the digestive system largely undigested, the bacteria naturally present in our gut can break them down. In the large intestine, undigested dietary fibers are fermented by the gut microbiota to produce short-chain fatty acids (SCFAs) like acetate and butyrate. These SCFAs lower the pH of the digestive tract, creating a more acidic environment which promotes the growth of good bacteria and discourages the overgrowth of bad bacteria. What’s more, the acidic environment supports the absorption of important minerals like calcium and magnesium. A study published last year found that just 2 weeks of a high-fiber diet was enough to significantly alter the study participants’ microbiomes. Consuming a diverse range of dietary fibers from a varied diet is associated with an increase in the diversity of gut bacteria. Low microbial diversity has been linked to increased risk of obesity, insulin resistance and diabetes.

2. Blood Glucose Control

Research has consistently shown that fiber can help improve blood glucose control, especially for those with type 2 diabetes. While fiber is found in carbohydrate-containing foods, both soluble and insoluble fiber pass through the digestive system without causing a spike in blood glucose. What’s more, soluble fiber can absorb water and slow digestion which improves the glycemic response to sugar or carbohydrates, leading to a more gradual increase in blood sugar rather than the “spike” associated with eating more refined carbohydrates. A scientific review of studies in 2020 concluded that higher-fiber diets are an important component of diabetes management, resulting in improvements in measures of glycemic control, blood lipids, body weight, and inflammation, as well as a reduction in premature mortality. Notably, these benefits were not confined to any fiber type or to any type of diabetes. The greatest improvements in glycemic control were observed for those moving from low to moderate or high intakes. Our Reduce daily capsules contain Fenugreek Seed Extract which has one of the highest concentrations of naturally occurring fiber that helps to slow down the digestion of carbohydrates and sugars.

3. Satiety and Weight Management

Studies have found that diets high in fat and low in fiber are associated with increased risk of being overweight or obese. There are many possible mechanisms behind why a high-fiber diet increases satiety and can support weight loss. Foods rich in fiber may displace foods that are more energy dense as high-fiber foods tend to be lower in calories than those with a low-fiber and higher fat content. Fiber forms a viscous mass in the stomach which delays gastric emptying, helping us to feel full for longer after eating. In general, research supports that a diet rich in fiber, whether from high-fiber foods or a fiber-enhanced supplement has a beneficial role in weight management. One study found that consuming a fiber-rich evening meal of brown beans (dietary fiber) suppressed hunger hormones such as ghrelin and increased satiety hormones measured the next morning. There is also growing evidence that the SCFAs generated from the breakdown of undigested fibers may improve satiety through the production of hormones that stimulate insulin secretion and increase glucose uptake.

4. Reduction of Cholesterol Levels

There is a large body of research that suggests intake of fiber from whole foods or supplements is protective against cardiovascular disease. A high-fiber diet can lower blood pressure, improve serum lipid levels, and reduce indicators of inflammation. Research suggests that certain fibers may be more protective. Oats and barley contain beta-glucan, a viscous, soluble fiber recognized for its cholesterol-lowering properties. A review of studies found that diets enriched with a minimum of 3g/day of beta-glucans showed improvements in LDL or “bad” cholesterol, total cholesterol and apoB, another biomarker associated with risk of heart disease. For context, 1.5 cups cooked oatmeal will provide 3g beta-glucans, while 1 cup cooked pearl barley will provide 2.5g.

So how much fiber do we need?

The Dietary Guidelines for Americans recommend that adult women get at least 25g fiber per day while men should aim for at least 31g, however over 90 percent of men and women do not meet those recommended intakes. If you’re looking for ideas to increase the fiber in your diet, check out the article here.