Fructans Are An Intestinal Favorite
A wide variety of foods—onions, garlic, leeks, Jerusalem artichoke, gobo root, chicory—contain chains of the sugar fructose. The long chains are derived from inulin, extracted from chicory root, while the short chains are called fructo-oligosaccharides, or simply FOS.
Fructans 'escape' digestion and thus add little to the calorie balance sheet. Additionally, FOS (15g/day for 3 weeks) appear to have no effect on blood sugar in diabetics.1 An additional upside is their 'fertilising' effect: Friendly bacteria (primarily bifidobacteria, and lactobacilli) in the intestines view fructans as a tasty meal, which promotes their growth. A recent study in which subjects received either 6g FOS, a specific acidophilus (2 billion/day; NCFM strain), or both, found only the FOS supplement to promote gut health as measured by protein-breakdown products.2
In an earlier study, researchers found 10g of a short chain of FOS boosted bifidobacteria and had only modest side effects.3 Some FOS supplementers experience gastrointestinal upset, marked primarily by excess gas and bloating. Among persons with chronic constipation, the 'loosening' effects of FOS may be beneficial. Elderly men supplementing with FOS (10g/day) for 30 days experienced a significant improvement in bowel function.4
In another study among elderly women and men, researchers found 4g of FOS twice/day for 3 weeks boosted both bifidobacteria and some markers of immune function, while lowering one marker of inflammation.5 However, the 'killing' activity of white blood cells was reduced in this group. Because the elderly are at risk for infections such as salmonella, and white blood cells represent one primary line of defence against intestinal infections, more research is needed among those with a higher risk of intestinal infections.
The use of FOS to modify blood lipids/cholesterol has also been a focus of research, due to 'by-products' made by the bacteria in the lower intestines after they devour this ultra low-calorie carbohydrate. Fructans appear to mildly lower only blood total and LDL cholesterol in persons with elevated cholesterol, but among subjects with 'normal' blood cholesterol, triglycerides decline.6 However, the researchers saw these effects in approximately half of the studies on lipid-altering effects of fructans. Scientists have yet to conduct studies to determine the long-term effects of fructan supplementation.
Diving Into Calcium
Virtually all of the calcium that makes its way into dietary supplements is originally mined from the earth and occurs as calcium carbonate. The same type of calcium is found in coral reefs. A spate of advertisements has claimed this form of calcium to be superior and more absorbable.
If we don scuba diving gear, however, we find little objective science to support such bubbly claims. In one human study, 12 people ate one serving of crackers fortified with either 525mg of calcium from Japanese coral (2:1 ratio of calcium to magnesium) or from terrestrial calcium carbonate.7 Using a less than exact method to assess calcium absorption, the study found a modestly higher response with coral calcium.
In another study, researchers found oral supplementation with a different Japanese coral calcium (17:1 ratio of calcium to magnesium) to produce a greater immune-stimulating-effect in mice compared with those given calcium carbonate.8 There do not appear to be any human studies examining the effects of coral calcium on bone density or bone metabolism, the real reason for supplementation with calcium (from any source). Because of the abundant human research supporting "land-derived" calcium carbonate and other forms of calcium (citrate, or citrate malate) on bone density, coral calcium appears to be more of a fish story and a possible long-term environmental gamble.
Anthony Almada, BSc, MSc, is co-founder of EAS and founder and chief scientific officer of IMAGINutrition in Laguna Niguel, California.
1. Alles MS, 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.
2. Swanson KS, et al. Fructooligosaccharides and Lactobacillus acidophilus modify bowel function and protein catabolites excreted by healthy humans. J Nutr 2002;132:3042-50.
3. Bouhnik Y, et al. Short-chain fructo-oligosaccharide administration dose-dependently increases fecal Bifidobacteria in healthy humans. J Nutr 1999;129:113-6.
4. Chen HL, et al. Effects of fructooligosaccharide on bowel function and indicators of nutritional status in constipated elderly men. Nutr Res 2002;20:1725-33.
5. Guigoz Y, et al. Effects of oligosaccharide on the faecal flora and non-specific immune system in elderly people. Nutr Res 2002;22:13-25.
6. Pereira DIA, Gibson G. Effects of consumption of probiotics and prebiotics on serum lipid levels in humans. Crit Rev Biochem Mol Biol 2002;37:259-81.
7. Ishitani K, et al. Calcium absorption from the ingestion of coral-derived calcium by humans. J Nutr Sci Vitaminol 1999;45:509-17.
8. Hirota Y, Sugisaki T. Effects of the coral calcium as an inhibitory substance against colon cancer and its metastasis in the lungs. Nutr Res 2000;20:1557-67.