What are prebiotics?

Answer 1

Prebiotics are parts of food that you can't digest directly.

When your partially digested meal arrives in your large intestine, it becomes the food for your probiotic microbes. Mother's milk contains sugars (galacto-oligosaccharides), which feed probiotic bacteria known as Bifidobacterium, which protect babies from gastrointestinal infections. In addition, probiotic bacteria thrive on the parts of plants that you can't digest directly, including oligofructose and inulin. Oligofructose is a fructooligosaccharide, which refers to a short chain of fructose molecules. Inulins are a group of polysaccharides, which means a long chain of sugar molecules. Since these prebiotics are composed of sugars, they are carbohydrates, and since they are indigestible and able to be dissolved in water, they are soluble fibers. Although you can't digest prebiotics, the probiotic bacteria in your colon can metabolize them through fermentation, releasing significant quantities of carbon dioxide, hydrogen, and methane. This process can sometimes cause intestinal gas; however, if you eat these prebiotic soluble fibers regularly, your body grows accustomed to them, and you experience fewer problems with gas.

Inulin and oligofructose are naturally present in many plant foods, and may help prevent constipation, promote enzyme activity and improve the pH levels in your colon. In addition, inulin promotes Lactobacillus acidophilus to produce butyrate, a beneficial short-chain fatty acid that helps inhibit inflammation in the intestinal tract. The following list shows foods in decreasing order of their average prebiotic content (values per 100 g):

Chicory root, raw: 41.6 g inulin, 22.9 g oligofructose

Jerusalem artichoke, raw: 18.0 g inulin, 13.5 g oligofructose

Dandelion greens, raw: 13.5 g inulin, 10.8 g oligofructose

Garlic, raw: 12.5 g inulin, 5.0 g oligofructose

Leek, raw: 6.5 g inulin, 5.2 g oligofructose

Asparagus, raw: 2.5 g inulin, 2.5 g oligofructose

Wheat bran, raw: 2.5 g inulin, 2.5 g oligofructose

Wheat flour, baked: 2.4 g inulin, 2.4 g oligofructose

Banana, raw: 0.5 g inulin, 0.5 oligofructose

Beans, peas, and lentils contain the oligosaccharides, raffinose and stachyose, that feed bifidobacteria, which suppress the activity of putrefactive bacteria, such as Clostridium in the colon. Good sources include:

Adzuki beans, raw: 0.2 g raffinose; 3.9 g stachyose

Soybeans, raw: 0.7 g raffinose; 3.2 g stachyose

Chickpeas, raw: 0.7 g raffinose; 2.4 g stachyose

Lima beans, raw: 0.4 g raffinose; 2.5 g stachyose

Black-eyed peas, raw: 0.5 g raffinose; 2.4 g stachyose

Peas, split, raw: 0.7 g raffinose; 2.1 g stachyose

Mung beans, raw: 0.8 g raffinose; 1.4 g stachyose

Lentils, raw: 0.3 g raffinose; 1.9 g stachyose

Beta glucans are sugars that are found in the cell walls of baker's yeast, shiitake mushrooms, and cereal grains, like barley, oats, rye, and wheat. They increase the number of probiotic bacteria in the intestines, especially in people over the age of fifty. Beta glucans stimulate the activity of macrophages, which are immune cells that ingest and demolish invading pathogens and stimulate other immune cells to attack. Macrophages also release cytokines, chemicals that enable the immune cells to communicate with one another. In addition, beta glucans stimulate lymphocytes (white blood cells) that bind to tumors or viruses, and release chemicals to destroy it. Beta glucans also help to lower total and low-density lipoprotein (LDL or "bad") cholesterol. Lentinan, a type of beta glucan found in shiitake mushrooms, is believed to reduce tumor activity and lessen the side effects of cancer treatment. Beta glucans also help your body do battle with bacteria resistant to antibiotic treatment and viruses that cause upper respiratory infections. They fight a form of Escherichia coli (ETEC), which cause traveler's diarrhea. They also fight upper respiratory infections from colds and flu.

Because only plants contain these probiotic-nourishing carbohydrates, vegans have much higher counts of probiotic bacteria than do meat eaters. Vegans who eat starches, vegetables, and fruits, which contain a wide variety of indigestible sugars that feed and stimulate the growth of probiotic bacteria, require no additional prebiotic supplements to obtain optimal health benefits form their probiotic microbes (natural or enhanced by probiotic supplements).

Answer 2

Prebiotics are non-digestible fibers that feed the beneficial bacteria in our gut, promoting their growth and activity. They are found in foods like onions, garlic, bananas, and whole grains, and are important for maintaining a healthy gut microbiome.