Gastroenterology

Gastroenterology

Volume 138, Issue 1, January 2010, Pages 65-72.e2
Gastroenterology

Reviews in Basic and Clinical Gastroenterology
Dietary Fiber Supplements: Effects in Obesity and Metabolic Syndrome and Relationship to Gastrointestinal Functions

https://doi.org/10.1053/j.gastro.2009.11.045Get rights and content

Dietary fiber is a term that reflects a heterogeneous group of natural food sources, processed grains, and commercial supplements. Several forms of dietary fiber have been used as complementary or alternative agents in the management of manifestations of the metabolic syndrome, including obesity. Not surprisingly, there is a great variation in the biological efficacy of dietary fiber in the metabolic syndrome and body weight control. Diverse factors and mechanisms have been reported as mediators of the effects of dietary fiber on the metabolic syndrome and obesity. Among this array of mechanisms, the modulation of gastric sensorimotor influences appears to be crucial for the effects of dietary fiber but also quite variable. This report focuses on the role, mechanism of action, and benefits of different forms of fiber and supplements on obesity and the metabolic syndrome, glycemia, dyslipidemia, and cardiovascular risk and explores the effects of dietary fiber on gastric sensorimotor function and satiety in mediating these actions of dietary fiber.

Section snippets

Dietary Fiber: Definition and Classification

The definition of dietary fiber is “the edible parts of plants or analogous carbohydrates that resist digestion and absorption in the human small intestine, with complete or partial fermentation in the human large intestine. It includes polysaccharides, oligosaccharides, lignin and associated plant substances. Dietary fiber exhibits one or more of either laxation, blood cholesterol attenuation and/or blood glucose attenuation.”5

Dietary fiber includes several chemical classes: nonstarch

Fiber and Body Weight

Epidemiologic studies suggest an inverse relation of dietary fiber intake and body weight,15, 16 and this is supported by cross-sectional studies (with body mass index17, 18, 19 or body fat mass20, 21) and large observational studies (body weight gain in women22 and in men23). Body weight gain was inversely correlated with the amount of whole grain ingested23 in the large-scale study on Coronary Artery Risk Development in Young Adults (CARDIA).24

Epidemiology and Mechanisms

Soluble dietary fiber is associated with lower postprandial glucose levels and increased insulin sensitivity in diabetic and healthy subjects, effects that are generally attributed to the viscous and/or gelling properties of soluble fiber.73, 74, 75 Insoluble dietary fiber exerts negligible effects in postprandial glycemia. However, epidemiologic evidence suggests the opposite.4, 76, 77, 78 Soluble dietary fiber consumption did not reduce the risk of type 2 diabetes mellitus in observational

Soluble fibers

Recent clinical trials98, 99, 100 and meta-analyses101, 102 support the cholesterol-lowering properties of soluble dietary fiber (pectin, guar gum, psyllium, and oat β-glucan). Low-density lipoprotein reductions of 6%–15% but no alterations in high-density lipoprotein or triglyceride levels have been consistently reported. Only a single study in patients with type 2 diabetes mellitus reported a 10% decrease in serum triglyceride levels after 6 weeks of a high-fiber diet particularly rich in

Fiber and Gastric Sensorimotor Functions Related to the Metabolic Syndrome

Given that influences of dietary fiber on metabolic and cardiovascular outcomes are in part related to gastrointestinal functions, it is relevant to review the known effects of dietary fiber on gastrointestinal functions and mechanisms of satiation, which are summarized in Table 2.

Conclusions

There are several studies showing that the general population and diabetic patients in the United States do not meet adequate mean daily fiber intake in their diets.118, 119, 120 On the other hand, there are clear and multiple benefits from the dietary incorporation of fiber supplements and natural foods and grains on the metabolic syndrome and CVD risk and, possibly, their prevention. The gastrointestinal tract is a crucial intermediary in these benefits through fiber modulation of gastric and

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    Conflicts of interest The authors disclose no conflicts.

    Funding Supported in part by grants R01 DK 67071 and K24 DK 02638 from the National Institutes of Health (to M.C.) and an international grant from the Hellenic Society of Gastroenterology (to A.P.).

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