Prebiotics For Digestive Health
Barley, oats and products made from them contain natural prebiotics
Prebiotics are the natural substances that support the growth and healthy activity of commensal organisms (microbes that live in our body in harmony with us without causing any damage) in our large intestines. They were discovered by Marcel Roberfroid, according to whom, "a prebiotic is a selectively fermented ingredient that allows specific changes, both in the composition and/or activity of gastrointestinal microflora, that confers benefits upon host well being and health."
Our digestive tract includes mouth, pharynx, food pipe (or esophagus), stomach, small intestines (duodenum, jejunum and ileum), large intestines (caecum, ascending colon, transverse colon, descending colon, sigmoid colon), rectum and anus. In normal adults, microbes on the surface of esophageal wall, are those that are swallowed with saliva and food. The contents of our stomach are acidic, so it is virtually sterile, except soon after eating. Bacterial colonies grow inside the stomach in people with stomach cancer, lack of acid secretion (achlorhydria) or obstruction. The number of bacteria increase progressively beyond the duodenum to the colon, being comparatively low in the small intestines. In the initial part of our small intestines (duodenum), there are around a thousand to one million bacteria per gram of contents, in the lower half of small intestines this number reaches around hundred thousand to hundred million bacteria per gram. In the first part of colon (ascending colon) the gut flora increase further, to reach up to ten billion microbes per gram of contents. In the small intestines, lactobacilli and enterococci are the main bacteria species. There are around a hundred billion bacteria per gram of contents in the lower part of colon and rectum, constituting 10-20% of the fecal mass.
Our large intestines contain microbes such as Escherichia coli, Enterobacter aerogenes, Bacteroides fragilis and gas gangrene bacilli, along with Lactobacillus, and a small number of Mycoplasma, Candida and other species. Great masses of these bacteria are passed in the stools. At birth the intestines are sterile. Bacterial flora get established within 4-24 hours after birth. These "friendly" bacteria require certain chemical substances, such as vitamin-C (ascorbic acid), cyanocobalamin and choline for their growth. They synthesize vitamin-K, a number of B-complex vitamins, and folic acid, that are essential for health and well being. The brown color of stools is due to pigments formed from bile by the intestinal bacteria.
When carbohydrates in our food are acted upon by these bacteria, certain organic acids are formed, that are responsible for the slightly acid reaction of the stools (pH 5.0-7.0). These intestinal bacteria also have a role in cholesterol metabolism. A number of potentially toxic substances such as histamine and tyramine are formed in the large intestines by the action of bacterial enzymes. Other amines, such as indole and skatole contribute to the odor of feces, as do the sulfides. Ammonia is a toxic chemical produced in, and absorbed from the large intestines, due to the action of these gut bacteria on proteins. When our liver gets damaged, this ammonia cannot be removed from the blood, and leads to severe brain damage (hepatic encephalopathy).
Our digestive tract contains loads to healthy bacteria that help in better absorption of nutrients
Benefits of prebiotics
- Strengthen body immunity.
- Prevent colon cancer
- Protect from inflammatory bowel diseases.
- Improve calcium absorption
Types Of Prebiotics
The three basic types of prebiotics include the following :
- Short chain prebiotics : These get fermented easily in the ascending part of large intestines, to provide nutrition to the gut flora in that area. Oligofructose is a type of short chain prebiotic.
- Longer chain prebiotic : These contain large chains of complex carbohydrates, that get fermented slowly, and provide food for the growth of "gut friendly bacteria" in the descending colon. Inulin is an example of this variant.
- Full spectrum prebiotics : As for example, oligofructose enriched inulin, these provide nourishment to the commensal bacteria throughout the large intestines.
Chicory roots contain prebiotic inulin that hastens the intestinal movements
Prebiotics prevent growth of harmful pathogens
Natural Sources Of Prebiotics
- Chicory root : Chicory is a woody perennial herb, the roots of which contain around 15-20% inulin, a carbohydrate similar to starch that has a sweetening power much less than that of sucrose or the normal cane sugar, and 5-10% oligofructose. The prebiotics derived from chicory roots assist in weight loss, improve intestinal movements and help cure constipation.
- Jerusalem artichoke : Also known as sun root, it is a species of sunflower. It contains 10% protein, no oil and lacks in starch. It contains a good amount of carbohydrate inulin (76%), which is a polymer of the fruit sugar fructose. It has a sweet taste due to the fruit sugar. It is a healthy option for people suffering from type-2 diabetes. Jerusalem artichokes are sometimes used as a substitute for potato, as they have similar consistency, similar texture in raw form, are sweeter, have a nuttier flavor, and are a perfect fit for salads in raw form. They become soft and mushy when boiled. The inulin contained in artichokes cannot be broken down and digested in our intestines, but gets metabolized by gut bacteria.
- Leek : This is a vegetable, with its edible part being a bundle of leaf sheaths, called stem or stalk. It belongs to the onion family. Leek can be boiled, fried or eaten raw.
- Garlic : A close relative of onion, it contains garlic fructan (12-24%), the prebiotic that provides protection against digestive disorders by improving the gut flora (it stimulates the beneficial bacteria to grow selectively, and retards the growths of harmful microbes).
- Onions : These contain good amounts of inulin and oligofructose, providing 6-18 gms of prebiotic compounds per serving. Onions help improve intestinal health, maintain normal pH (pH denotes the concentration of hydrogen ions or the acid level) of intestines and improves the activity of enzymes of digestion.
- Asparagus : Shoots of asparagus are stir fried or grilled. Asparagus contains 93% water and a good amount of vitamins-B1, B2, B3 or niacin, B6, folic acid, rutin, beta carotene, vitamins- C, E, K,proteins and dietary fiber. It is also loaded with minerals such as iron, calcium, magnesium, zinc, copper,potassium, phosphorus, manganese, selenium and chromium. It is low in calories, and has a low sodium content. It is a good source of inulin, and stimulates intestinal bacteria to produce butyric acid, a short chain fatty acid that reduces inflammation and promotes digestive health.
- Wheat bran : It is the hard outer layer of the wheat grain. It is rich in dietary fiber, essential fatty acids, prebiotic carbohydrates, proteins, vitamins, minerals and phytic acid.
- Wheat flour (baked) : It is a powder made by grinding wheat. It contains fructans and arabinoxylans, the natural non-digestible carbs that have prebiotic properties and enhance iron absorption from our intestines.
- Raw banana : It is an edible fruit with soft flesh. It is rich in starch, vitamin-B6, C, manganese, potassium and dietary fiber. The soluble fiber found in banana that dissolves in water to form a gel, is rich in prebiotics fructo-oligosaccharides, which include inulin and oligofructose. it is also high in resistant starches that cannot be digested but get fermented by good bacteria and enable them to thrive in the intestines.
- Beans : Red kidney beans, pinto beans and black beans are high in starch, protein, dietary fiber,minerals such as iron, potassium, selenium, molybedenum, and vitamins - B1, B6 and folic acid.
- Jicama or mexican yam or turnip : This is an edible tuber that contains good amounts of carbohydrates and dietary fiber. It contains 86-90% water,vitamin-C and mineral potassium, along with trace amounts of oil and proteins. It has a sweet flavor due to the oligofructose inulin which is a prebiotic.
- Raw oats : These are rich sources of a soluble fiber beta glucan, which is a class of indigestible polysaccharides.
- Unrefined barley : Germinated barley contains hemicellulose, other dietary fibers, has a high water holding capacity and promotes the production of short chain fatty acids in large intestines, and can reduce risk of Ulcerative Colitis.
- Yacon : This is a perennial plant with sweet tasting tuberous roots. It is similar to the mexican yam, slightly sweet and resinous. Also known as Peruvian Ground Apple, it mainly contains water and inulin,the prebiotic that provides typical floral undertones to its flavor.
Foods Rich In Prebiotics
Prebiotic fiber content
Dry chicory root
Around 4-8 gms (6 gms on an average) of prebiotic intake is essential for a strong and healthy digestive system. To achieve this amount, you require a daily serving of around 9.3 gms of chicory roots, or 19 gms of jerusalem artichokes, or 34 gms of garlic, or 50 gms of leek, or 70 gms of raw onions, or 120 gms of raw asparagus, or 120 gms of wheat bran or 4.4 oz or 125 gms of cooked wheat flour, or 600 gms or 1.3 lb of banana, or a combination of these, in varying amounts. People with digestive disorders require around 15 gms of prebiotics daily, that is two and a half times more than that required by normal individuals.
Jicama or Mexican yam
Health Benefits Of Prebiotics
These plant substances provide nourishment and a healthy medium for the growth of bifidobacteria and lactic acid bacteria. These microbes are the gut friendly or the good bacteria that help improve digestion and absorption of minerals, and strengthen our body immunity. The beneficial effects of regular daily consumption of a diet rich in prebiotics, include the following :
- Improves calcium absorption : Inulin and other prebiotics slightly increase the acid level in our intestines. This increases the solubility of calcium, magnesium and other minerals in the gut, increases the expression of calcium binding proteins and enhances calcium uptake by cells on the inner lining of intestines. This has a beneficial effect on mineralization of bones.
- Strengthens body immunity : Daily consumption of prebiotics improves our ability to respond to intestinal infections, and also reduces inflammation.
- Reduces risk of colorectal cancer : On long term intake, these plant foods hasten the movement of semi-digested food through the intestines. This reduces the exposure of inner lining of large intestines to the potential toxins. They also increase the healthy gut flora, reduce intestinal inflammation, reduce the number of pathogens and bind to the cancer causing chemicals or carcinogens present in food, thus reducing the risk of cancer colon.
- Reduce risk of inflammatory bowel disorders (Ulcerative colitis and Crohn's disease) : Prebiotics support the growth of gut flora and stimulate them to produce short chain fatty acids that repair the inner lining of large intestines and prevent Crohn's disease. These fatty acids increase the acid levels of large intestines. This inhibits the growth of sulfate producing bacteria, which in turn decreases production of hydrogen sulfide gas in the intestines. This provides protection against Ulcerative colitis.
- Reduction in high blood pressure
- Maintain normal pH of intestines and regular bowel movements : Growth of good bacteria in the intestines causes an increase in fecal bulk and improves stool frequency and reduces constipation.
Initial problems with prebiotics
You should begin your intake of these plant foods with small servings, and gradually increase their amount in your diet. A sudden excessive intake of these substances can lead to gas formation and bloating.