Fructo-oligosaccharides (FOS) and Other Oligosaccharides

Also indexed as: Inulin Oligosaccharides, Oligosaccharides

What does it do? The term “oligosaccharide” refers to a short chain of sugar molecules (“oligo” means “few” and “saccharide” means “sugar.”) Fructo-oligosaccharides (FOS) and inulin, which are found in many vegetables, consist of short chains of fructose molecules. Galacto-oligosaccharides (GOS), which also occur naturally, consist of short chains of galactose molecules. These compounds can be only partially digested by humans.1 2 3 4 When oligosaccharides are consumed, the undigested portion serves as food for “friendly” bacteria, such as Bifidobacteria and Lactobacillus species. Clinical studies have shown that administering FOS, GOS, or inulin can increase the number of these friendly bacteria in the colon while simultaneously reducing the population of harmful bacteria.5 6 7 8 9 Other benefits noted with FOS, GOS, or inulin supplementation include increased production of beneficial short-chain fatty acids such as butyrate, increased absorption of calcium and magnesium, and improved elimination of toxic compounds.10 11

Because FOS, GOS, and inulin improve colon function and increase the number of friendly bacteria, one might expect these compounds would help relieve the symptoms of irritable bowel syndrome. However, a double-blind trial found no clear benefit with FOS supplementation (2 grams three times daily) in patients with this condition.12 Experimental studies with FOS in animals suggest a possible benefit in lowering blood sugar levels in people with diabetes and in reducing elevated blood cholesterol and triglyceride levels.13

In a double-blind trial of middle-aged men and women with elevated cholesterol and triglyceride levels, supplementation with inulin (10 grams per day for eight weeks) significantly reduced insulin concentrations (suggesting an improvement in blood-glucose control) and significantly lowered triglyceride levels.14 In a preliminary trial, administration of FOS (8 grams per day for two weeks) significantly lowered fasting blood-sugar levels and serum total-cholesterol levels in patients with type 2 (non-insulin-dependent) diabetes.15 However, in another trial, people with type 2 diabetes supplementing with FOS (15 grams per day) for 20 days found no effect on blood-glucose or lipid levels.16 In addition, double-blind trials of healthy people showed that supplementing with FOS or GOS for eight weeks had no effect on blood-sugar levels, insulin secretion, or blood lipids.17 18 Because of these conflicting results, more research is needed to determine the effect of FOS and inulin on diabetes and lipid levels.

Several double-blind trials have looked at the ability of FOS or inulin to lower blood cholesterol and triglyceride levels. These trials have shown that in people with elevated total cholesterol or triglyceride levels, including people with type 2 diabetes, FOS or inulin (in amounts ranging from 8 to 20 grams daily) produced significant reductions in triglyceride levels. However, the effect on cholesterol levels was inconsistent.19 20 21 22 In people with normal or low cholesterol or triglyceride levels, FOS or inulin produced little effect.23 24 25

Where is it found? FOS and inulin are found naturally in Jerusalem artichoke, burdock, chicory, leeks, onions, and asparagus. FOS products derived from chicory root contain significant quantities of inulin,26 a fiber widely distributed in fruits, vegetables and plants, which is classified as a food ingredient (not as an additive) and is considered to be safe to eat.27 In fact, inulin is a significant part of the daily diet of most of the world’s population.28 FOS can also be synthesized by enzymes of the fungus Apergillus niger acting on sucrose. GOS is naturally found in soybeans and can be synthesized from lactose (milk sugar). FOS, GOS, and inulin are available as nutritional supplements in capsules, tablets, and as a powder.

FOS, GOS, and inulin have been used in connection with the following conditions (refer to the individual health concern for complete information):

Rating Health Concerns
2Stars Elevated triglyceride levels
1Star Diabetes
Pre- and post-surgery health
3Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1Star An herb is primarily supported by traditional use, or the herb or supplement has little scientific support and/or minimal health benefit.

Who is likely to be deficient? As FOS, GOS, and inulin are not essential nutrients, no deficiency state exists.

How much is usually taken? The average daily intake of oligosaccharides by people in the United States is estimated to be about 800 to 1,000 mg. For the promotion of healthy bacterial flora, the usual recommendation for FOS, GOS, or inulin is 2,000 to 3,000 mg per day with meals. In the studies on diabetes and high blood lipids (cholesterol and triglycerides), amounts ranged from 8 to 20 grams per day.

Are there any side effects or interactions? Generally, oligosaccharides are well tolerated. Some people reported increased flatulence in some of the studies. At higher levels of intake, that is, in excess of 40 grams per day, FOS and the other oligosaccharides may induce diarrhea.

There is a report of a 39-year old man having a life-threatening allergic reaction after consuming high amounts of inulin from multiple sources, including FOS.29 Allergy to inulin in this person was confirmed by laboratory tests. Such sensitivities are extremely rare. People with a confirmed sensitivity to inulin should probably avoid FOS.

At the time of writing, there were no well-known drug interactions with Fructo-oligosaccharides (FOS) and Other Oligosaccharides.

References:

1. Molis C, Flourie B, Ouarne F, et al. Digestion, excretion, and energy value of fructooligosaccharides in healthy humans. Am J Clin Nutr 1996;64:324–8.

2. van Dokkum W, Wezendonk B, Srikumar TS, van den Heuvel EG. Effect of nondigestible oligosaccharides on large-bowel functions, blood lipid concentrations and glucose absorption in young healthy male subjects. Eur J Clin Nutr 1999;53:1–7.

3. Alles MS, Hautvast JGA, Nagengast FM, et al. Fate of fructo-oligosaccharides in the human intestine. Br J Nutr 1996;76:211–21.

4. Roberfroid M. Dietary fibre, inulin and oligofructose. A review comparing their physiological effects. Crit Rev Food Sci Nutr 1993;33:103–48 [review].

5. Gibson GR, Beaty ER, Cummings JH. Selective stimulation of bifidobacteria in the human colon by oligofructose and inulin. Gastroenterology 1995;108:975–82.

6. Bouhnik Y, Flourie B, D’Agay-Abensour L, et al. Administration of transgalacto-oligosaccharides increases fecal bifidobacteria and modifies colonic fermentation metabolism in healthy humans. J Nutr 1997;127:444–8.

7. Bhounik Y, Vahedi K, Achour L, et al. Short-chain fructo-oligosaccharide administration dose-dependently increases fecal bifidobacteria in healthy humans. J Nutr 1999;129:113–6.

8. Roberfroid MB, Van Loo JAE, Gibson GR. The bifidogenic nature of chicory inulin and its hydrolysis products. J Nutr 1998;128:11–9.

9. Roberfroid M. Dietary fibre, inulin and oligofructose. A review comparing their physiological effects. Crit Rev Food Sci Nutr 1993;33:103–48 [review].

10. Tomomatsu H. Health effects of oligosaccharides. Food Technology 1994;October:61–5 [review].

11. van den Heuvel EG, Muys T, van Dokkum W, Schaafsma G. Oligofructose stimulates calcium absorption in adolescents. Am J Clin Nutr 1999;69:544–8.

12. Hunter JO, Tuffnell Q, Lee AJ. Controlled trial of oligofructose in the management of irritable bowel syndrome. J Nutr 1999;129:1451S–3S.

13. Delzenne NM. The hypolipidaemic effect of inulin: when animal studies help to approach the human problem. Br J Nutr 1999;82:3–4 [review].

14. Jackson KG, Taylor GRJ, 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;82:23–30.

15. Yamashita K, Kawai K, Itakura M. Effect of fructo-oligosaccharides on blood glucose and serum lipids in diabetic subjects. Nutr Res 1984;4:961–6.

16. Roberfroid M. Dietary fibre, inulin and oligofructose. A review comparing their physiological effects. Crit Rev Food Sci Nutr 1993;33:103–48 [review].

17. van Dokkum W, Wezendonk B, Srikumar TS, van den Heuvel EG. Effect of nondigestible oligosaccharides on large-bowel functions, blood lipid concentrations and glucose absorption in young healthy male subjects. Eur J Clin Nutr 1999;53:1–7.

18. Luo J, Rizkalla SW, Alamowitch C, et al. Chronic consumption of short-chain fructooligosaccharides by health subjects decreased basal hepatic glucose production but had no effect on insulin-stimulated glucose metabolism. Am J Clin Nutr 1996;63:939–45.

19. Yamashita K, Kawai K, Itakura M. Effect of fructo-oligosaccharides on blood glucose and serum lipids in diabetic subjects. Nutr Res 1984;4:961–6.

20. Jackson KG, Taylor GRJ, Clohessy AM, Wlliams 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;82:23–30.

21. Roberfroid M. Dietary fibre, inulin and oligofructose. A review comparing their physiological effects. Crit Rev Food Sci Nutr 1993;33:103–48 [review].

22. Davidson MH, Synecki C, Maki KC, Drennen KB. Effects of dietary inulin in serum lipids in men and women with hypercholesterolaemia. Nutr Res 1998;3:503–17.

23. Luo J, Rizkalla SW, Alamowitch C, et al. Chronic consumption of short-chain fructooligosaccharides by health subjects decreased basal hepatic glucose production but had no effect on insulin-stimulated glucose metabolism. Am J Clin Nutr 1996;63:939–45.

24. Pedersen A, Sandstrom B, van Amelsvoort JMM. The effect of ingestion of inulin on blood lipids and gastrointestinal symptoms in healthy females. Br J Nutr 1997;78:215–22.

25. van Dokkum W, Wezendonk B, Srikumar TS, van den Heuvel. Effect of nondigestible oligosaccharides on large-bowel functions, blood lipid concentrations and glucose absorption in young healthy male subjects. Eur J Clin Nutr 1999;53:1–7.

26. Duke JA. Handbook of phytochemical constituents of GRAS herbs and other economic plants. Boca Raton, FL: CRC Press, 1992.

27. Carabin IG, Flamm WG. Evaluation of safety of inulin and oligofructose as dietary fiber. Regul Toxicol Pharmacol 1999;30:268–82 [review].

28. Coussement PA. Inulin and oligofructose: safe intakes and legal status. J Nutr 1999;129:1412S-7S [review].

29. Gay-Crosier F, Schreiber G, Hauser C. Anaphylaxis from inulin in vegetables and processed food. N Engl J Med 2000;342:1372 [letter].