Generally in nutrition education, there is a focus on the macroscopic level: which foods are “good,” which are “bad” and how to build healthy eating habits. For some individuals, however, learning about specific components of food can be beneficial to improving health.
One component of food that is universally praised by health experts is fiber. Fiber is all forms of carbohydrate that are consumed but not digested in the body. Because they are not digested, fibers are able to slow sugar digestion, and thus help regulate blood glucose levels and appetite.
Fiber intake is also related to decreased cancer development for a number of reasons. Fiber is converted to short-chain fatty acids, which are known anti-carcinogens. Dietary fiber also increases antioxidant levels and increases estrogen excretion, thereby removing carcinogenic substances.
Arguably the most convincing reason to eat more fiber is reduced susceptibility to cardiovascular disease. Fiber reduces cholesterol synthesis and other biomarkers that may indicate future heart disease.
There are two types of this invaluable nutrient, each with its own benefits. Soluble fiber is frequently found in fruits, vegetables and beans, and causes slower digestion and reduced appetite — especially in more viscous fibers, such as pectin, the fiber often found in fruits. It is also specifically responsible for lowering cholesterol and managing blood sugar.
Insoluble fiber is concentrated in whole grains, potatoes and nuts, but is also present in smaller amounts in the foods listed as being heavy in soluble fibers. Insoluble fiber prevents constipation and lowers risk of colon cancer and hemorrhoids. Clearly, very important.
Both types of fiber play key roles in regulating digestive health. However, their importance is also tied to the foods they are found in. Fibers are found exclusively in plant foods, which are generally nutrient dense and minimally processed. As a result, consuming a fiber containing food often improves health by adding vitamins and minerals to the diet as well. This may partially explain why fiber supplements are thought to be inferior to dietary fiber.
In recent years, fiber deficiency has emerged as an explanation for the chronic disease epidemics in many westernized countries. While the U.S. and U.K. governments advocate for around 30 g/day of fiber, the average person consumes about half of this. In areas with very high fiber intake, such as Uganda and Tanzania, rates of many chronic diseases are drastically reduced. For this reason, some health experts have suggested raising the recommended intake of fiber.
Like all nutrients, there are downsides to excess fiber. In rare cases, typically on produce-heavy diets (raw/whole foods), people may experience bloating or gas after high fiber intake above 70 g/day. Symptoms of high fiber intake can be managed by lowering intake or increasing water consumption, as water is used to break down soluble fibers.
Despite its well-researched impacts on cholesterol, blood sugar and heart disease, and the increasing focus on health consciousness in the U.S., only about 5% of Americans have sufficient fiber intake. Increasing fiber intake requires incorporating more whole foods like fruits, vegetables, whole grains and legumes in your diet — foods that contain loads of other nutrients as well.
So, save your own rear end, and the rest of you — get some fiber in your diet!
