Johnson W. McRorie

Viscous versus nonviscous soluble fiber supplements: Mechanisms and evidence for fiber-specific health benefits

Purpose: This review focuses on the health benefits of viscous versus nonviscous soluble fibers, why symptoms can occur with increased fiber consumption, and how to avoid symptoms to improve adherence with a high‐fiber diet. Data sources: Review of scientific literature as well as evidence‐based guidelines and resources. Conclusions: While it is generally known that “fiber is good for you,” it is less well known that specific health benefits are associated with specific fiber characteristics. Many of the health benefits of fiber can be directly correlated with the viscosity of soluble fibers when hydrated (i.e., gel‐forming). A reduction in viscosity of a given fiber will attenuate these health benefits, and a nonviscous fiber does not exhibit these health benefits. Implications for practice: Increasing the viscosity of chyme with a viscous soluble fiber has been shown clinically to lower cholesterol for cardiovascular health, improve glycemic control in type 2 diabetes, normalize stool form in both constipation (softens hard stool) and diarrhea (firms loose/liquid stool), and improve the objective clinical measures of metabolic syndrome (glycemic control, lipoprotein profile, body mass index/weight loss, and blood pressure).

Psyllium fiber improves glycemic control proportional to loss of glycemic control: a meta-analysis of data in euglycemic subjects, patients at risk of type 2 diabetes mellitus, and patients being treated for type 2 diabetes mellitus

BACKGROUND A number of health benefits are associated with intake of soluble, viscous, gel-forming fibers, including reduced serum cholesterol and the attenuation of postprandial glucose excursions. OBJECTIVE We assess the effects of psyllium, which is a soluble, gel-forming, nonfermented fiber supplement, on glycemic control in patients who were being treated for type 2 diabetes mellitus (T2DM) and in patients who were at risk of developing T2DM. DESIGN A comprehensive search was performed of available published literature (Scopus scientific database) and clinical records stored by Procter & Gamble with the use of key search terms to identify clinical studies that assessed the glycemic effects of psyllium in nondiabetic, pre-T2DM, and T2DM patients. RESULTS We identified 35 randomized, controlled, clinical studies that spanned 3 decades and 3 continents. These data were assessed in 8 meta-analyses. In patients with T2DM, multiweek studies (psyllium dosed before meals) showed significant improvement in both the fasting blood glucose (FBG) concentration (-37.0 mg/dL; P < 0.001) and glycated hemoglobin (HbA1c) [-0.97% (-10.6 mmol/mol); P = 0.048]. Glycemic effects were proportional to baseline FBG; no significant glucose lowering was observed in euglycemic subjects, a modest improvement was observed in subjects with pre-T2DM, and the greatest improvement was observed in subjects who were being treated for T2DM. CONCLUSIONS These data indicate that psyllium would be an effective addition to a lifestyle-intervention program. The degree of psylliums glycemic benefit was commensurate with the loss of glycemic control. Because the greatest effect was seen in patients who were being treated for T2DM, additional studies are needed to determine how best to incorporate psyllium into existing prevention and treatment algorithms with concomitant hypoglycemic medications.

Histamine2-receptor antagonists: Rapid development of tachyphylaxis with repeat dosing.

Histamine2-receptor antagonists (H2RAs) are available over-the-counter (OTC) for the treatment and prevention of heartburn, but more than occasional, single-dose use can lead to rapid development of tachyphylaxis. The aim of this review is to assess the published evidence regarding the development of tachyphylaxis with repeat usage of H2RAs. PubMed and SCOPUS were searched across all years to identify clinical studies that examined the development of tachyphylaxis with repeated dosing of H2RAs. Although a single (first) dose of an H2RA can be effective for controlling gastric acid and preventing or relieving food-related heartburn, numerous studies confirm that tachyphylaxis, also known as tolerance, is consistently detected at the first time point assessed after the first dose, including the second day and/or second dose. Even if symptom relief is achieved with an H2RA, it may be due to desensitization of the esophagus to acid exposure, potentially providing symptom relief without significantly decreasing esophageal acid exposure. When recommending OTC drugs for treatment of frequent heartburn, clinicians should be aware of the potential for rapid development of tachyphylaxis in patients who use H2RAs for 2 or more consecutive days. Even if symptom relief is achieved, it may be due to desensitization of the esophagus to acid by the H2RA, potentially providing symptom relief without significantly decreasing esophageal acid exposure. Other strategies, such as an OTC proton pump inhibitor, may be needed to optimize management of frequent heartburn.

Fiber supplements and clinically proven health benefits: How to recognize and recommend an effective fiber therapy

Background Only 5% of adults consume the recommended level of dietary fiber. Fiber supplements appear to be a convenient and concentrated source of fiber, but most do not provide the health benefits associated with dietary fiber. Purpose This review will summarize the physical effects of isolated fibers in small and large intestines, which drive clinically meaningful health benefits. Data sources A comprehensive literature review was conducted (Scopus and PubMed) without limits to year of publication (latest date included: October 31, 2016). Conclusions The physical effects of fiber in the small intestine drive metabolic health effects (e.g., cholesterol lowering, improved glycemic control), and efficacy is a function of the viscosity of gel-forming fibers (e.g., psyllium, β-glucan). In the large intestine, fiber can provide a laxative effect if (a) it resists fermentation to remain intact throughout the large intestine, and (b) it increases percentage of water content to soften/bulk stool (e.g., wheat bran and psyllium). Implications for practice It is important for nurse practitioners to understand the underlying mechanisms that drive specific fiber-related health benefits, and which fiber supplements have rigorous clinical data to support a recommendation. Clinical pearl For most fiber-related beneficial effects, “Fiber needs to gel to keep your patients well.”Abstract Background Only 5% of adults consume the recommended level of dietary fiber. Fiber supplements appear to be a convenient and concentrated source of fiber, but most do not provide the health benefits associated with dietary fiber. Purpose This review will summarize the physical effects of isolated fibers in small and large intestines, which drive clinically meaningful health benefits. Data sources A comprehensive literature review was conducted (Scopus and PubMed) without limits to year of publication (latest date included: October 31, 2016). Conclusions The physical effects of fiber in the small intestine drive metabolic health effects (e.g., cholesterol lowering, improved glycemic control), and efficacy is a function of the viscosity of gel‐forming fibers (e.g., psyllium, β‐glucan). In the large intestine, fiber can provide a laxative effect if (a) it resists fermentation to remain intact throughout the large intestine, and (b) it increases percentage of water content to soften/bulk stool (e.g., wheat bran and psyllium). Implications for practice It is important for nurse practitioners to understand the underlying mechanisms that drive specific fiber‐related health benefits, and which fiber supplements have rigorous clinical data to support a recommendation. Clinical pearl For most fiber‐related beneficial effects, “Fiber needs to gel to keep your patients well.”

Fermented Fiber Supplements Are No Better Than Placebo for a Laxative Effect

BackgroundMisconceptions about the effects of dietary fiber and ‘functional’ fiber on stool parameters and constipation persist in the literature.MethodsA comprehensive literature review was conducted with the use of the Scopus and PubMed scientific databases to identify and objectively assess well-controlled clinical studies that evaluated the effects of fiber on stool parameters and constipation.ResultsThe totality of well-controlled randomized clinical studies show that, to exert a laxative effect, fiber must: (1) resist fermentation to remain intact throughout the large bowel and present in stool, and (2) significantly increase stool water content and stool output, resulting in soft/bulky/easy-to-pass stools. Poorly fermented insoluble fiber (e.g., wheat bran) remains as discreet particles which can mechanically irritate the gut mucosa, stimulating water & mucous secretion if the particles are sufficiently large/coarse. For soluble fibers, some have no effect on viscosity (e.g., inulin, wheat dextrin) while others form high viscosity gels (e.g., β-glucan, psyllium). If the soluble fiber is readily fermented, whether non-viscous or gel-forming, it has no effect on stool output or stool water content, and has no laxative effect. In contrast, a non-fermented, gel-forming soluble fiber (e.g., psyllium) retains its gelled nature and high water-holding capacity throughout the large bowel, resulting in soft/bulky/easy-to-pass stools.ConclusionWhen considering a recommendation for a fiber supplement regimen to treat and/or prevent constipation, it is important to consider which fibers have the physical characteristics to exert a laxative effect, and which fiber supplements have rigorous clinical evidence of a significant benefit in patients with constipation.

Evidence‐based treatment of frequent heartburn: The benefits and limitations of over‐the‐counter medications

Purpose: This review summarizes the pharmacological effects of over‐the‐counter (OTC) heartburn drugs, and the implications for treating frequent heartburn. Data sources: PubMed and SCOPUS were searched across all years to identify well‐controlled, randomized clinical studies that assessed mechanism of action and efficacy. Conclusions: Antacids can transiently neutralize acid in the esophagus, but do not significantly affect gastric pH or prevent subsequent heartburn episodes. Histamine‐2 receptor antagonists (H2RAs) rapidly develop tolerance with repeat dosing, and exhibit an analgesic effect that may provide heartburn relief while leaving the esophagus exposed to acid. Proton pump inhibitors (PPIs) provide a sustained inhibition of gastric acid production, and are superior to antacids and H2RAs for control of gastric acid and treatment of frequent heartburn. Implications for practice: When recommending therapies for frequent heartburn, it is of particular importance to understand the strengths and weaknesses of available OTC medications. Antacids and H2RAs are not recommended for treatment of frequent heartburn, while OTC PPIs are both indicated for, and effective for, treatment of frequent heartburn. A PPI dose of 20 mg is optimal for empiric treatment of frequent heartburn, and consistent with the 2013 treatment guidelines established by the American College of Gastroenterology (ACG) for treatment with a minimum effective dose.

Omeprazole-Mg 20.6 mg is superior to lansoprazole 15 mg for control of gastric acid: a comparison of over-the-counter doses of proton pump inhibitors

Aliment Pharmacol Ther 31, 846–851

Prunes vs. psyllium for chronic idiopathic constipation

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Meta-Analysis of Usefulness of Psyllium Fiber as Adjuvant Antilipid Therapy to Enhance Cholesterol Lowering Efficacy of Statins

Statins are usually well-tolerated drugs with a clear dose-dependent efficacy. However, manifestation of statins side effects also bears a direct relation to higher doses necessary to achieve high impact cholesterol-lowering effects. Nevertheless, the reliance on statin efficacy alone has often left dietary intervention underutilized even though studies have shown a reduction in serum cholesterol levels when dietary fiber intake is increased. In this meta-analysis, we investigated whether the concomitant use of psyllium, a gel-forming viscous soluble fiber, would cause further overall cholesterol lowering in subjects already receiving statins. A systematic review of the medical literature was performed and identified three randomized, controlled clinical studies that evaluated the cholesterol lowering efficacy of statins when given concomitantly with psyllium as a fiber supplement. The duration of the studies ranged from 4 weeks to 12 weeks. The objective of the meta-analysis was to estimate the overall effect of psyllium plus statin versus statin alone. The results of the meta-analysis showed a clinically and statistically significant (p = 0.001) cholesterol lowering advantage for psyllium plus statin combination treatment over a statin alone. Adding psyllium fiber resulted in reductions in low-density lipoprotein-cholesterol equivalent to doubling the statin dose. In conclusion, the data support that psyllium fiber takenbefore meals adds to the efficacy of statins, providing an easy to implement dietary intervention for those who cannot tolerate side effects associated with higher-dose statins.

Psyllium Is Superior to Wheat Dextrin for Lowering Elevated Serum Cholesterol

The Dietary Reference Intakes for fiber are based on an association between a high-fiber diet and a reduced risk of cardiovascular disease. Only 5% of Americans consume the recommended levels of dietary fiber; most consume approximately half the recommended level. If a fiber supplement is used to achieve the recommended level, it is important that the isolated fiber has the requisite physical properties to reduce the risk of cardiovascular disease by lowering elevated serum low-density lipoprotein and total cholesterol. The current study was designed to directly assess the cholesterol-lowering effects of psyllium, a natural nonfermented viscous/gel-forming fiber, versus wheat dextrin, a semisynthetic, readily fermented nonviscous supplement. The study was a 3-month, randomized, parallel-group design (n = 20 enrolled) that assessed psyllium husk (3.4 g) and wheat dextrin (3.5 g) dosed 3 times a day before meals. The results showed that gel-forming psyllium significantly (P < .05) lowered both low-density lipoprotein cholesterol (−17%) and total cholesterol (−11%), without affecting high-density lipoprotein cholesterol, versus wheat dextrin. In conclusion, clinicians and consumers should be aware that the physical characteristics of a fiber supplement determine whether it will provide specific health benefits, and it is recommended to only take those fiber supplements with evidence of clinically meaningful health benefits from well-controlled clinical studies.