Dr. Jaclyn Chasse is a naturopathic physician and Medical Educator at Emerson Ecologics, President of the New Hampshire Association of Naturopathic Doctors explains that "Prebiotics" describes a category of nutrients that support the growth of the healthy microflora that populate your large intestine. They include selectively fermented ingredients that result in specific changes in the activity of gastrointestinal microbiota, specifically increasing probiotic bacteria. When probiotic bacteria are allowed to colonize and flourish, they help to keep many systems of your body healthy, including your immune system.
Probiotics play a key role in regulating immune function, they influence the gut barrier by modulating the production of mucous, reducing bacterial adhesion (of pathogenic bacteria), tightening cell junctions and inducing an appropriate response of IgA, one of the first lines of immune defense. In addition to supporting the growth of probiotic microflora, prebiotic nutrients may also have their own beneficial effects on the immune system.
In one study, prebiotic supplementation increased fecal secretory IgA and postnatal immune development in infants. Prebiotics have also demonstrated a modest effect on symptoms in patients with Crohns disease. Research is not clear on the mechanisms behind these benefits, or whether the supplementation was helpful due to their impact on microflora. With symbiotic relationships such as this, the beneficial results conferred are likely due to a combination of factors involving both the prebiotics and probiotics including effects from the by products of their interactions, such as the creation of powerful anti-inflammatory short chain fatty acids (SCFAs), a metabolic byproduct of prebiotic fermentation by probiotic bacteria.
Prebiotics can be supplemented, but they can also be easily integrated into the diet. Most prebiotics are soluble fibers. The most well-recognized prebiotics are inulin and fructooligosaccharides (FOS), both of which occur naturally in many foods. Some of these foods include chicory root, garlic, onion, and many other vegetables and fruits. There are no recommended daily intakes established for prebiotic fibers, but most studies demonstrate an effect with between 4-8g for a healthy individual and 15-20g for someone with an active digestive disorder.
Chicory root is the most concentrated source of prebiotic fiber. It contains almost 65% prebiotic fiber by weight. Other foods that are very high in prebiotics include Jerusalem artichokes, dandelion greens, garlic, leek, onion, asparagus, wheat (especially the bran or whole wheat flour) and bananas. For most of these foods, consuming them raw transmits more of the prebiotic benefit than when cooked.
In addition to these foods naturally containing prebiotics, there are additional "superfoods" hitting the marketplace with either high natural quantities of prebiotics or supplemented levels; these include yogurts, breads, cereals, and drinks. Naturally fermented foods such as sauerkraut, kimchi, pickles, kefir, and miso contain high levels of prebiotics.
Prebiotics are also available in a supplement form. As previously mentioned, the most common forms of supplemented prebiotics include inulin and FOS. Prebiotics are easy to consume as a powder, as normally their taste is mildly sweet and they are soluble in water or juice. They can also be found encapsulated and are often used as a filler in probiotic products.
Whether prebiotics benefit our immune system all on their own, or it is their symbiotic relationship with probiotic bacteria that supports healthy immunity, it is none-the-less an important aspect in maintaining overall wellness. Somehow though, don't think the saying will ever change to "an onion a day, keeps the doctor away!"
21 October 2011