Fiber Supplements Not as Effective as Natural Fiber

Many clinical studies have demonstrated the association between a high-fiber diet and decreased levels of inflammation, a risk factor for cardiovascular disease. Elevated levels of C-reactive protein (CRP), a marker of inflammation, are common in overweight individuals, and associated with the risk for developing cardiovascular disease, diabetes, and hypertension. The American Heart Association recommends a high-fiber diet of around 25 to 30 grams of fiber per day. Based on evidence demonstrating the beneficial effect of a high-fiber diet on inflammatory markers for cardiovascular disease, the authors of a study published earlier this year in Annals of Family Medicine set out to determine whether a daily fiber supplement would be effective in reducing the levels of CRP and other inflammatory markers in overweight individuals.

The clinical trial included a racially diverse group of 132 overweight or obese adults with no history of heart disease. Participants were divided into three groups. The high-fiber group consisted of 35 individuals who each consumed 14 grams per day of psyllium fiber supplements in powder form, dissolved in water, while the low-fiber group of 45 people took 7 grams of supplement per day. The control group of 52 people took no supplement during the three-month period. Patients were monitored for levels of CRP, fibrinogen, and interleukin-6 (IL-6), as well as their white blood cell count (WBC). All of these are considered inflammatory markers associated with cardiovascular risk. Measurements were taken at baseline, and again after three months.

At the end of the three-month period, participants had no significant changes in inflammatory marker levels, other than a decrease in fibrinogen levels in the high-fiber group. These results stand out against other studies that show an association between dietary fiber and levels of CRP and other inflammatory markers; however, the authors referred to similar results from one clinical trial where psyllium fiber supplementation caused no significant change in the CRP levels of a smaller group of individuals with high blood pressure. The authors concluded that dietary supplementation with psyllium fiber alone did nothing to decrease the level of CRP and other inflammatory markers in overweight or obese individuals.

These results are a letdown for people hoping to increase their fiber intake and improve health-related risk factors by use of a psyllium fiber supplement. Fiber supplements may not be the best way to measure the effects of a particular nutrient on health-related risks, or to obtain fiber in the diet. The authors suggest that further study with other fiber supplements or other nutrient combinations may be helpful in developing a better understanding of the relationship between dietary fiber and the risk of heart disease. The results of this study do nothing to cancel out the overwhelming evidence that a diet high in natural fiber, that includes plenty of fruits and vegetables, has a positive effect on risk factors for cardiovascular disease and other health problems.

References

King, D., Mainous, A., Egan, B., Woolson, R., Geesey, M.

Effect of Psyllium Fiber Supplementation on C-Reactive Protein: The Trial to Reduce Inflammatory Markers (TRIM)

http://www.annfammed.org/cgi/content/full/6/2/100