Ask the Science Team: Fiber

Welcome to our first Ask the Science Team post! Every few months, someone from Unicity’s science team will address questions people have asked about Unicity, its products, and the industry.

For our first post in this series, Dr. Stephanie Kung, R&D scientific affairs specialist at Unicity, gives us the low-down on fiber. Read on to learn more about fiber and why it is so crucial in our diets.

What is dietary fiber?

Dietary fibers are plant-derived carbohydrates that can be found in many fruits, vegetables, whole grains, and legumes. Unlike other nutrients, fiber resists digestion and absorption in the small intestine. Instead, it passes through the digestive tract, and some fibers are fermented in the colon by the microorganisms (the gut microbiota) that reside there. The gut microbiota metabolizes fermentable fibers to produce short-chain fatty acids, which are beneficial compounds thought to have effects on cholesterol and glucose metabolism.

Why do we need dietary fiber?

Dietary fiber is well-documented for having beneficial effects on gastrointestinal health as a whole. Some benefits of fiber intake include regulating digestion, nutrient absorption, gut transit time, and microbiota health and diversity.

What's the difference between soluble and insoluble fiber?

Traditionally, fiber has been chemically classified as either soluble or insoluble depending on whether or not it can dissolve in water. Both types are naturally found together in plant sources and are important components of a balanced diet.

Most soluble fibers, like pectin and gums, dissolve in water to form a thick gel-like consistency. They can help improve stool regularity and satiety, allowing you to feel fuller for longer. Soluble fiber is also thought to have beneficial metabolic effects, such as supporting normal healthy blood cholesterol and glucose levels. Some good sources of soluble fiber include beans, carrots, apples, flax seed, and oats.

Insoluble fiber, like cellulose, does not dissolve in water and instead increases stool bulk. This is why increasing insoluble fiber intake is often a good idea for those looking to promote stool regularity and reduce occasional constipation or diarrhea. Good sources of insoluble fiber include whole grains, beans, and root vegetables.

What are prebiotics?

A prebiotic is a type of soluble fiber, also called a fermentable fiber. To be classified as a prebiotic, it must selectively promote the growth or activity of one or more beneficial microorganisms in the colon. Prebiotics act as a food source for our intestinal microbiota, and many research groups are actively studying the effects of prebiotics on a number of areas in human health, including cardiovascular health and weight management. Examples of prebiotics include inulin and fructo-oligosaccharides.

What benefits can I see from increasing my fiber intake?

Currently, more than 90 percent of American adults do not meet the recommended intake for dietary fiber. Many health factors that appear to be affected by fiber consumption are interrelated, such as body weight, glucose metabolism, and cholesterol levels. In addition to digestive health, adequate fiber intake may support normal healthy glucose levels, cholesterol levels, and body weight.

Regular bowel function: Both insoluble and soluble fiber are beneficial for symptoms of occasional constipation and promoting regularity. Dietary fiber can have a laxative effect that stimulates bowel movements, increases water content in the colon, and/or increases stool bulk, allowing for easier passage through the gastrointestinal tract and elimination of waste.

Cholesterol support: Many observational studies suggest an association between adequate fiber intake and supporting normal, healthy cholesterol levels. These effects appear to be mainly due to soluble fiber intake and appears to be more pronounced with viscous, gel-forming fibers like beta glucan in oats.

Blood sugar and insulin: Consumption of certain fibers (e.g., glucan) may lower the glucose and insulin response to a meal. A fiber-rich meal can slow gastric emptying from the stomach, which slows glucose absorption in the small intestine and consequently affects the insulin response. Moreover, a recent systematic review reported that high fiber consumption was associated with improvements in insulin sensitivity, glycemic control, and body weight.

Appetite and weight management: Dietary fiber intake can increase satiety, helping you to feel fuller from a meal. Some fibers that bind water can increase stomach distention, which signals to the brain that you are full. Increased satiety and decreased hunger can lead to reduced caloric intake, which over time can help with weight management. In addition, many foods naturally high in fiber are lower in fat and calories, which can benefit weight management. Combined with healthy habits, such as mindful eating (e.g., being conscious of portion sizes and consuming nutrients from a variety of whole foods) and regular exercise, increasing your fiber intake can be a good strategy for managing your weight.

Will I experience any side effects when I increase my fiber take?

For some individuals, increasing fiber intake may result in gastrointestinal discomfort (e.g., bloating, gas, loose stools, constipation) due to the increased amount of fiber available for the gut microbiota to metabolize. This is because one of the products of microbial fermentation is gas, and rapid gas production can cause these digestive symptoms. If you experience these symptoms, it may help to start with a smaller serving of the fiber supplement to allow time for your digestive system to adjust to this dietary change.