The taxonomy of food ingredients commonly divides the macronutrients into three general categories: proteins, fats and carbohydrates. But sometimes, this can be misleading. It would be fairer to add a fourth category: food fiber.
Fiber is usually considered a carbohydrate (although lignins, while composed of carbon, hydrogen and oxygen, technically are not considered carbohydrates since they are not made up of linked single sugar molecules). The compounds we call fiber are not only pervasive in the food supply, for food and beverage manufacturers they serve two completely different functions.
Fiber is a basic building block of many food products, providing or adding structure, texture and emulsifying or similar properties. Fiber also is included in formulations as a nutraceutical ingredient, specifically to impart a healthy functionality, such as for digestive health or satiety.
Certainly there is crossover, such as when an ingredient like inulin is added to bring a smooth creaminess to a lowered-fat sauce or dressing, or when resistant starch from high-amylose corn is traded for 20 percent of the wheat flour in a leavened baked item such as muffins to provide a higher fiber label designation without compromising volume. (In fact, in the case of resistant starch, in many such formulations volume can actually improve by up to 3 percent.) But the primary goal of including fiber in a product is where processors place their purchasing decisions.
For this reason, the fibers used on the health front are enjoying a burst of attention from researchers. Of those, perhaps none more so than beta-glucans. Beta-glucans in one of their most common forms are known as cellulose, a polysaccharide made up of a string of single glucose units connected to each other across an oxygen molecule bridge.
Beta-glucans can exist as single strands or branch off into side branches and form double- or triple-stranded helices. They form soluble fibers and, while known as having nutraceutical functionality beneficial to cardiovascular health, specifically as being able to lower serum cholesterol, recent trends in science indicate certain beta-glucan formations could help boost the immune system.
Common sources of beta-glucans have been oats and barley, but impressive research indicates that beta-glucans from mushrooms could become a trending ingredient. Studies of human stomach and colorectal cancer patients showed a positive effect from beta-glucans derived from shiitake mushrooms, bringing laboratory backing to several millennia of ancient Chinese medicine.
More than a dozen years ago, in a comprehensive review of medicinal mushrooms, “Therapeutic Effects of Substances Occurring in Higher Basidiomycetes Mushrooms: A Modern Perspective,” published in the journal Immunology, authors Solomon Wasser and Alexander L. Weis described “some of the recently isolated and identified substances of higher Basidiomycetes mushrooms origin that express promising antitumor, immune modulating, cardiovascular and hypercholesterolemia, antiviral, antibacterial and antiparasitic effects.”
In traditional Chinese medicine (TCM), specific mushrooms have been described as beneficial for cancers of the stomach, esophagus, lungs, breast and other organs. Medicinal mushrooms also have been used to treat diabetes, kidney disease and a host of other dysfunctions. In their review, Wasser and Weis wrote, “There are about 200 species of mushrooms that have been found to markedly inhibit the growth of different kinds of tumors.”
Wasser and Weis specifically noted that “several antitumor polysaccharides such as hetero-beta-glucans and their protein complexes (e.g., xyloglucans and acidic beta-glucan-containing uronic acid), as well as dietary fibers, lectins, and terpenoids have been isolated from medicinal mushrooms.” Other research studies have shown tumorocidal effects from oat and barley beta-glucans.
The idea of dietary fiber as an anti-cancer nutraceutical is not necessarily new. Nutritionists have been aware for decades of the ability of dietary fiber to help prevent colon cancer. But most of the attention was on this benefit as a secondary effect, the presumed result of speeding up motility and cleaning the lower gastrointestinal tract.
Resistant starch was shown to positively alter the chemistry in the gut in a way beneficial to cancer prevention. Yet some studies are showing signs of an apoptosis (programmed cell death) effect in cancer cells secondary to inclusion of resistant starch in the diet.
So certain fibers, especially mushroom beta-glucans, exhibit such strong beneficial health properties that they go beyond prevention of disease to actually mitigating certain disease states. Developers of healthy foods and beverages can up their game beyond burying fiber with other nutritional carbohydrates or as structural linchpins in formulations.