Prebiotic Foods

A prebiotic is defined as “nondigestible food compounds that are indigestible by humans but are digestible by intestinal bacteria and thus serve as an energy source for beneficial bacteria that live in the human intestine. The human intestine contains about 300-500 different species of bacteria that can be divided into health-promoting ones, like Bifidobacteria and Lactobacilli and into harmful ones such as some types of Clostridia. Prebiotics help to stimulate the growth of one or a limited number of bacteria in the colon, cultivate healthy bowel flora, particularly bifidobacteria, that beneficially affects the host and thus improves the host's health”. Increasing bifidobacteria has been associated with a wide array of health benefits ranging from decreases in insulin to improved mental health.

Galacto-oligosaccharides (GOS) are short chains of variable length made up of the sugars galactose and glucose. GOS are considered prebiotics, which support the most favorable growth of Bifidobacteria and Lactobacilli. GOS have numerous purported beneficial effects. GOS stimulates calcium absorption and the absorption of magnesium can be improved as well. GOS can offer relief to constipation by increasing the frequency of defecation, soften the stools and improve stool consistency.

GOS are believed to mimic the oligosaccharides found naturally in human breast milk and may contribute to the known health benefits of breastfeeding. Infant formulas in Europe have been supplemented with GOS since 2001, and numerous studies support the safety and prebiotic effects of GOS supplementation in infants. In Europe, formulas containing up to eight grams of GOS per liter are considered safe for infants, and a prebiotic mixture of 10% long-chain inulin and 90% GOS has been added to infant formulas since 2001.

Oligosaccharides are generally considered to be safe when consumed as part of normal diet. In several studies, a lack of adverse effects was observed. The side effects of galactooligosaccharides (GOS) intake are mild laxative effects and gas. Symptoms may be more severe if consumed by sensitive individuals or if large quantities are consumed. The GOS-rich foods are legumes that contain amylopectin, which has the potential to affect blood sugar, and lectins, which are indigestible and potentially inflammatory in some people depending on blood type, and phytates that bind calcium, magnesium, iron, and zinc and make them unavailable for absorption. Some people also advocate extended soaking to reduce phytate content, but this also reduces the GOS content by around 25%, as well. Galactooligosaccharides (GOS) may interact with alcohol, caffeine, calcium salts, foods containing calcium, drugs that weaken the immune system, laxatives, mineral oil, foods containing phytic acid, foods containing other prebiotics, foods containing vitamin D and herbs.

To increase GOS, there are expensive nutritional supplements you can buy that contain beta glucan sources from oats. Commercial preparations of GOS (Bi2muno®) may contain up to 25% lactose in liquid form and up to 30% lactose in powder form. I recommend that you obtain nutrients from real, whole foods, the way Nature’s wisdom provides. Small portions are ideal. Maximum benefits and tolerability of GOS fibers occurs at an intake in the neighborhood of 5 grams per day. (naturally in human and bovine milk).

The fermentation by of galacto-oligosaccharides and isomaltooligosaccharides by specific beneficial bacteria produces the least volume of gas when compared to other prebiotic oligosaccharides. However, fructans and alpha-linked galactose-containing oligosaccharides, such as those found in various legumes and beans, can be fermentationed by a number of other colonic bacteria that do produce more gas; (lentils, chickpeas/hummus, green peas, Lima beans, kidney beans).

Isomaltulose is a disaccharide carbohydrate composed of glucose and fructose; (honey, sugarcane juice, and black-strap molasses).

Inulins are a group of naturally occurring polysaccharides produced by many types of plants. Industrially inulin is most often extracted from chicory. The inulins belong to a class of dietary fibers known as fructans. Inulin is used by some plants as a means of storing energy and is typically found in roots or rhizomes. Most plants that synthesize and store inulin do not store other forms of carbohydrate such as starch. Due to its resistance to digestive enzymes, inulin remains in tact until it reaches the large intestine, where it is converted by colonic bacteria to a gel known as a prebiotic that is highly nourishing to gut microflora; (banana/plantain, chicory, dandelion, garlic, globe artichoke, Jerusalem artichoke (pictured below), jicama, onion).

jerusalem artichoke raw
Jerusalem Artichokes have a delicate nutty flavor that you don't want to miss. I cook them in a skillet with butter and salt. They are excellent for increased intestinal motility!


Isomalto-oligosaccharides (IMO) is a mixture of short-chain carbohydrates that naturally occur as a plant-based dietary fiber, which resist digestion-resistant and has a prebiotic effect, soluble, and low-glycemic; (rice miso, fermented soy sauce, honey).

Raffinose oligosaccharides is a trisaccharide composed of galactose, glucose, and fructose; (beans, cabbage, Brussels sprouts, broccoli, asparagus, other vegetables, and whole grains).

Fructooligosaccharides (FOS) are oligosaccharides that occur naturally in plants; (asparagus, beet, garlic, chicory, onion, Jerusalem artichoke, honey, banana, barley, tomato, and rye). Also Heather’s Tummy Fibers and sprouted wheat (sprouted spelt flour, Sprouted Spelt bread & Ezekiel bread).

Heathers soluble fiber IBS constipation


Xylooligosaccharides (XOS) are sugar oligomers made up of xylose units. Avoid supplementation if you have a known allergy or hypersensitivity to lactose; (bamboo shoots, fruits, vegetables, milk, and honey).

Cultivate variety in your diet
No single prebiotic fiber will fully cultivate wide species diversity of healthy different beneficial microbial species because each “prefers” different fibers, based on their ability to metabolize them. While some prefer GOS, others prefer FOS, inulin or other fibers. To cultivate species diversity in beneficial bacteria species, your prebiotic fiber routine should include a variety of prebiotic fiber in your diet every day. Fiber-rich sources are just one ingredient in the overall effort toward optimal health.

Primitive cultures who have not been exposed to antibiotics, processed foods, additives, solvents, chlorinated water, plastics, pesticides, herbicides, hybridized grains and all the other factors that disrupt bowel flora composition, have a wide diversity of microbial species, as compared to the narrower range of species in people of industrialized, modern cultures.

Prebiotics differ from probiotics
Probiotics are bacteria (such as Lactobacillus and Bifidobacterium) often taken as supplements to promote the establishment of beneficial gut bacteria.

Every day I have beet, globe artichoke, dandelion (in season), Heather's Tummy Fibers, onion and garlic in my salad. I have broccoli, asparagus and Brussel sprouts, each once a week, as part of my weekly vegetable rotation. Daily, I have a ‘Prebiotic Patty’ with my vegetables at lunch every day. See Recipe blog - "What's for lunch?"

If you are interested in obtaining the beneficial effects of prebiotic fibers, note that these are strategies that should only be pursued if you do not have dysbiosis. (Prebiotic fibers will make dysbiosis worse, as indicated by abdominal pain, excessive bloating and gas, and diarrhea, since they feed undesirable microbial species as well as desirable.)

If you have been told or suspect you have Small Intestinal Bacterial Overgrowth (SIBO), Small intestinal Fungal Overgrowth (SIFO), Food or environmental allergies or intolerance, Leaky Gut, Candida Yeast Overgrowth or Systemic Candidiasis, please reach out to me via email to schedule your free introductory consultation. I can help you get your health and your life back on track.