What Is It?
Health Benefits

Dosage Information

Guidelines for Use

General Interaction

Possible Side Effects

Evidence Based Rating Scale

What Is It?

Fructo-oligosaccharides (FOS) are nondigestible dietary fibers that help to keep the stomach and bowels healthy. They do this by nourishing and promoting the naturally present "friendly" bacteria (Bifidobacteria and Lactobacilli in particular) that help to ward off infection in the digestive system. Because of these properties, FOS is considered a "prebiotic". Quite popular in Japan, such prebiotics have just started to become available in the United States.

FOS are found in high concentrations in Jerusalem artichoke and in fruits and vegetables like asparagus, bananas, barley, garlic, jicama, leeks, onions, tomatoes and wheat. The FOS, made up of plant sugars linked in chains, are extracted from these foods for use in medicines and as a sweetener for foods.

Prebiotics should not be confused with "probiotics", which  also are gaining in popularity. These are actually live organisms found in various foods and supplements that are used to re-colonize the intestines with beneficial microorganisms; for example, the acidophilus in yogurt is a commonly recognized probiotic. Both prebiotics and probiotics can modify the composition of intestinal bacteria in beneficial ways. When combined, prebiotics and probiotics are sometimes referred to as “synbiotics” indicating that they work synergistically together: the prebiotic helps to create a more favorable growth environment for the probiotic.

Health Benefits

By promoting the growth of beneficial bacteria and increasing overall gastrointestinal tract health, FOS may help to treat digestive disorders, such as irritable bowel syndrome, constipation, and flatulence. Preliminary research indicates that both prebiotics and probiotics may help to protect the digestive tract from cancerous growths. Prebiotics such as FOS are also being studied for their effects on reducing serum cholesterol and for preventing food allergies.

Specifically, fructo-oligosaccharides may help to:

Treat irritable bowel syndrome (IBS). FOS may benefit people who suffer from irritable bowel syndrome, a mysterious and often painful digestive disorder that can cause alternating bouts of diarrhea and constipation. The exact cause of this condition remains to be determined, but an imbalance in the varieties of bacteria in the intestine is one possibility. FOS's prebiotic action may help to restore order in the bowel and control symptoms. Especially when taken in conjunction with a probiotic, FOS may help to enhance digestion and ease symptoms of IBS. In a 2006 open, uncontrolled multi-center study of 636 men and women with constipation-type IBS, taking 3 grams daily of the synbiotic combination of FOS with Bifidobacterium longum W11 increased stool frequency in patients with constipation-variant IBS and reduced abdominal pain and bloating in those with moderate to severe symptoms. (1) However, results from studies evaluating FOS taken alone to treat IBS are mixed. In a 2000 multi-center, prospective, randomized, double-blind placebo-controlled trial, 96 patients with IBS received either 10 - 20 grams of FOS powder or placebo for twelve weeks. After four to six weeks of treatment, symptoms improved more in the placebo group than in the FOS group. At completion of the study, there were no significant differences between the two groups. Symptoms improved in 58% of the FOS group and in 65% of the placebo group while symptoms worsened in 8% and 13% of the FOS and placebo groups, respectively. (2) However, conflicting evidence exists. In a 2008 randomized, double-blind study of 105 adults with IBS, taking 5 grams of FOS daily for six weeks led to a significant decrease in the intensity of digestive symptoms in the FOS group compared to the placebo group along with significant improvement in ability to perform daily activities. 75% of subjects in the FOS group experienced symptoms less frequently compared to 58.3% in the control group. (3) More research is needed.

Relieve constipation and flatulence. Preliminary evidence indicates that FOS may relieve constipation by increasing fecal mass. In a 2001 study of seven elderly men, taking 10 grams of FOS for 30 days (after a 30-day control, low-fiber diet period) improved bowel movements, stool output and stool bulk in the colon without any adverse effects. (4) In a 2011 randomized, double-blind, placebo-controlled study of 20 women and 16 men, significant improvement in overall self-reported gastrointestinal symptoms and bowel habits was observed in the group taking a synbiotic combination of FOS with a combination of probiotics including: Lactobacillus acidophilus La5, Bifidobacterium animalis ssp. lactis Bb-12, Lactobacillus delbrueckii ssp. bulgaricus, Lactobacillus paracasei ssp. paracasei, Streptococcus thermophilus. (5) More research is needed.

Lower cholesterol. Animal studies have shown that consumption of FOS lowers serum cholesterol levels. (6-8) Human trials, however, have shown mixed results, with one study showing improved lipid profiles after FOS consumption, and others finding no significant effects. (9, 10) Researchers believe long-term consumption of FOS may produce modest but beneficial changes, as the positive results were seen during an 8-week trial, while the negative results were seen in two trials that lasted only 20 and 28 days. More research is needed.

Reduce risk of eczema. The development of atopic eczema, a non-contagious skin inflammation, often caused by allergies, that produces itchy, red, rash-like areas, has been correlated with higher colonic concentrations of harmful bacteria and a decreased concentration of Bifidobacteria in infants. (11-13) A high concentration of these harmful bacteria can indirectly lead to increased exposure to potential antigens, thus increasing the risk of developing atopic eczema. Supplementation with FOS has been shown to reduce colonic concentrations of these harmful bacteria, bringing intestinal flora back into balance. (14) Other studies have shown the ability of Bifidobacterium to alleviate the symptoms of infantile atopic eczema; so the potential for FOS to stimulate the growth of Bifidobacterium may be beneficial in treating atopic eczema. (13, 15) Research in humans is needed.

Prevent cancer. Preliminary research indicates that prebiotics may help to detoxify and protect the digestive tract from the growth of certain cancers, such as colon cancer. Studies in mice have shown that FOS reduces the incidence of colon tumors. (16, 17)


  • Capsule
  • Food
  • Powder

Dosage Information

For constipation: 10 g daily has been used.

For flatulence: 10 g daily has been used.

For IBS: 3 - 20 g daily has been used.

Guidelines for Use

When taking prebiotics, it is best to start at a lower dose (3 g daily) and slowly increase dosage, to reduce the risk of adverse reactions.

Don't confuse prebiotics with probiotics, which are live organisms used to re-colonize beneficial intestinal flora.

General Interaction

There are no known drug or nutrient interactions associated with FOS.

Possible Side Effects

Supplementation can cause flatulence, belching, abdominal pain, intestinal sounds, and bloating at the onset of treatment. Symptoms are generally mild at lower doses (less than 10 g daily).


FOS supplements appear to be quite safe.


1. Colecchia A, Vestito A, La Rocca, et al. Effect of a synbiotic preparation on the clinical manifestations of irritable bowel syndrome, constipation-variant. Results of an open, uncontrolled multicenter study. Minerva Gastroenterol Dietol. 2006 Dec;52(4):349-58.
2. Olesen M, Gudmand-Hoyer E. Efficacy, safety, and tolerability of fructooligosaccharides in the treatment of irritable bowel syndrome. Am J Clin Nutr. 2000 Dec;72(6):1570-5.
3. Paineau D, Payen F, Panserieu S, et al. The effects of regular consumption of short-chain fructo-oligosaccharides on digestive comfort of subjects with minor functional bowel disorders. Br J Nutr. 2008 Feb;99(2):311-318.
4. Chen HL, Lu YH, lin JJ, Ko LY. Effects of fructooligosaccharide on bowel function and indicators of nutritional status in constipated elderly men. Nutr Res. 2000;20:1725-33.
5. Nova E, Viadel B, Wärnberg J, et al. Beneficial effects of a synbiotic supplement on self-perceived gastrointestinal well-being and immunoinflammatory status of healthy adults. J Med Food. 2011 Jan-Feb;14(1-2):79-85.
6. Fiordaliso M, Kok N, Desager JP, et al. Dietary oligofructose lowers triglycerides, phospholipids and cholesterol in serum and very low density lipoproteins of rats. Lipids. 1995;30:163-7.
7. Kok N, Roberfroid M, Robert A, Delzenne N. Involvement of lipogenesis in the lower VLDL secretion induced by oligofructose in rats. Br J Nutr. 1996 Dec;76(6):881-90.
8. Jackson KG, Taylor GR, Clohessy AM, Williams CM. The effect of the daily intake of inulin on fasting lipid, insulin and glucose concentrations in middle-aged men and women. Br J Nutr. 1999 Jul;82(1):23-30.
9. Pedersen A, Sandstrom B, van Amelsvoort JM. The effect of ingestion of inulin on blood lipids and gastrointestinal symptoms in healthy females. Br J Nutr. 1997;78:215-222.
10. Alles MS, de Roos NM, Bakx JC, et al. Consumption of fructooligosaccharides does not favorably affect blood glucose and serum lipid concentrations in patients with type 2 diabetes. Am J Clin Nutr. 1999;69:64-9.
11. Bjorksten B, Sepp E, Julge K, et al. Allergy development and the intestinal microflora during the first year of life. J Allergy Clin Immunol. 2001;108:516-20.
12. Kalliomaki M, Kirjavainen P, Eerola E, et al. Distinct patterns of neonatal gut microflora in infants in whom atopy was and was not developing. J Allergy Clin Immunol. 2001;107:129-134.
13. Kirjavainen PV, Arvola T, Salminen SJ, Isolauri E. Abberant composition of gut microbiota of allergic infants: a target of bifidobacterial therapy at weaning? Gut 2002;51-55.
14. Gibson GR, Beatty ER, Wang X, Cummings JH Selective stimulation of bifidobacteria in the human colon by oligofructose and inulin. Gastroenterology. 1995;108:975-982.
15. Isolauri E, Arvola T, Sutas Y, et al. Probiotics in the management of atopic eczema. Clin Exp Allergy. 2000;30:1604-10.
16. Pierre F, et al. Short-chain fructo-oligosaccharides reduced the occurrence of colon tumors and develop gut-associated lymphoid tissue in Min mice. Cancer Res. 1997;57:225-8.
17. Pierre F, Perrin P, Bassonga E, et al. T cell status influences colon tumor occurrence in min mice fed short chain fructo-oligosaccharides as a diet supplement. Carcinogenesis. 1999/20:1953-6.

Evidence Based Rating Scale

The Evidence Based Rating Scale is a tool that helps consumers translate the findings of medical research studies and what our clinical advisors have found to be efficacious in their personal practice into a visual and easy to interpret format. This tool is meant to simplify the information on supplements and therapies that demonstrate promise in the treatment of certain conditions.








Preliminary studies in animals indicate potential efficacy to prevent tumor growth. Research in humans is needed. (16, 17)

Preliminary evidence in animals indicates efficacy, but trials in humans are conflicting. More research is needed. (6-10)
One small trial indicates potential efficacy. More research is needed. (4)

Preliminary studies indicate potential efficacy to prevent and treat atopic eczema in infants. More research is needed. (11-15)
One small trial indicates potential efficacy when taken with probiotics. (5)
Irritable bowel syndrome  
Conflicting evidence exists. More research is needed. (1-3)

Date Published: 04/18/2005
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