How Fiber Supports The Immune System.

We are bombarded by information on fiber.  The majority of it, along with countless advertisements directed at the aging population, focus on the importance of fiber for regularity.

What isn’t talked about is the importance of fibers’ role in supporting the immune system.

Soluble vs Insoluble Fiber

Fiber is basically a wide range of carbohydrates that humans lack the enzymes to digest.

Most fiber is placed in two groups, soluble and insoluble.

Insoluble fiber is primarily a bulking agent and passes through the digestive tract mostly intact.  It helps the body process waste better, prevents and treats constipation, and improves bowel health. It releases few, if any, calories as it moves through the gut.

Soluble fiber dissolves with water and gastrointestinal fluids in the gut to form a gel-like, viscous substance.  It helps increase the feeling of satiety, reduces blood sugar spikes, and may reduce the risk of heart disease.

Although humans lack the enzymes necessary to break down most fiber, the friendly bacteria that live in the gut are able to digest (ferment) soluble fiber and use it as fuel. This in turn produces the short-chain fatty acids so critical to optimal health.

Starch vs. Non-Starch Polysaccharides

Polysaccharides are the most abundant form of carbohydrates found in plants and, by definition, are made up of multiple simple sugars (known as monosaccharides) that are chemically bound together. With the correct digestive enzymes, polysaccharides can be broken down into simple sugars (like glucose) and be used as energy by plants, animals and humans.

In general, polysaccharides are divided into two groups; storage and structure.

·         Starch = Storage:  Starch is a polysaccharide that is the stored form of sugar in plants. Plants produce glucose through photosynthesis.  Any excess glucose is stored as starch in various parts of the plant including the roots and seeds. Humans have the digestive enzymes necessary to break down starch into glucose which is absorbed in the small intestine and used as energy.

 ·         Non-starch = Structure: Cellulose and pectin are two examples of non-starch polysaccharide. They comprise cell walls and provide the structure in plants, giving fruits and veggies their crunchiness. Although we do not have the enzymes to break these down, it’s used as food by beneficial gut microbiota.

Resistant Starch

By design, certain types of starch escape digestion in the small intestine and move on to the colon.  This type of starch is known as resistant starch. It is referred to as a prebiotic and functions like soluble fiber in the gut, feeding the good bacteria.

Beta-glucans and the Immune System

Beta-glucans are a non-starch polysaccharide found in the cell walls of mushrooms, seaweed, algae and certain whole grains.

They are a prebiotic, soluble fiber that offer immune modulating benefits to both the innate and adaptive immune systems. They boost immune function by stimulating T-cells, neutrophils, macrophages, natural killer cells, monocytes and dendritic cells.

Beta-glucans derived from mushrooms, such as the maitake, appear to be especially potent immunomodulators, and yeast-derived beta-glucans positively impact the inflammatory and antimicrobial activities of cells in the innate immune system.

In clinical cancer treatments they have been shown to inhibit tumor growth and metastasis and have also demonstrated anti-osteoporotic activities.

Initial research has also shown beta-glucans seem to support healthy upper respiratory function and may be extremely beneficial to high-risk populations. 

All of this in addition to supporting balanced blood sugar, improving insulin sensitivity, promoting healthy cholesterol levels, and demonstrating anti-diabetes and anti-obesity effects.

Fiber provides so much more than regularity. In supporting the immune system, fiber supports the foundation of overall health.

Be sure to include at least 38 grams of dietary fiber daily for men, 25 grams for women, preferably from whole foods. 

References

Effects of beta-glucans on the immune system – PubMed

Immune-enhancing effect of water-soluble beta-glucan derived from enzymatic hydrolysis of yeast glucan – PubMed

The effects of beta-glucan on human immune and cancer cells – PubMed

Structure and Function of Carbohydrates | Biology for Majors I

Dietary roles of non-starch polysaccharides in human nutrition: a review – PubMed

Effect of BETA 1, 3/1, 6 GLUCAN on Upper Respiratory Tract Infection Symptoms and Mood State in Marathon Athletes – PMC