Written by Susan Sweeny Johnson, PhD, Biochem. In a study with 35 healthy volunteers, a measure of hypertension reduced a marker of inflammation by 13.5% with a standard anti-hypertensive diet and 18.2% when 1 oz of psyllium fiber was added.
Recent studies have shown a strong connection between inflammation and cardiovascular disease as well as insulin resistance, hypertension, the development of diabetes mellitus, and the metabolic syndrome. (1,2,3) Metabolic syndrome affects perhaps 25% of the US population and is characterized by insulin resistance, high blood pressure, fat around the waist, lowered HDL, and elevated triglycerides. One key measure of inflammation is the presence of elevated c-reactive protein (CRP). Since high-fiber diets seem to be associated with lowered risk of cardiovascular disease and possibly inflammation, (5) researchers recently studied the effects of natural or supplemented high-fiber diets on levels of blood CRP.
Thirty-five healthy, non-hypertensive volunteers were given one of two diets rich in fiber: the Dietary Approaches to Stop Hypertension [DASH] diet (6) which is recommended by the National Heart Lung and Blood Institute containing 27.7 gm per day of natural fiber, or a normal diet supplemented by 26.3 gm per day of psyllium fiber. It should be noted that the calorie content and distribution of nutrients in the normal diet were adjusted to match the DASH diet. Blood samples were analyzed before the study and after 3 weeks on each diet.
Levels of CRP dropped significantly after three weeks on either diet:
*CRP at baseline: 4.4mg/L
*CRP after DASH 3.8mg/L (P=0.046)
*CRP after supplemented diet: 3.6 mg/L (P=0.03)
Most notably, when the data for the subset of obese volunteers were compared with the subset of lean volunteers, the lean group showed a significant drop in CRP upon fiber consumption in either diet while the obese group showed no significant reductions in CRP. At baseline, CRP was much higher in the obese group (7.2 gm/L) compared to the lean group (2.0 mg/L). Therefore, inflammation is reduced at least in lean individuals on a high-fiber diet.
The researchers suggested that a longer term study should be performed to see if a significant reduction in CRP and therefore inflammation could be achieved in an obese population at elevated risk for cardiovascular and other metabolic diseases.
Source: King, Dana E., Brent M. Egan, Robert F. Woolson, Arch G. Mainous, Yaser Al-Solaiman, and Ammar Jesri. “Effect of a high-fiber diet vs a fiber-supplemented diet on C-reactive protein level.” Archives of Internal Medicine 167, no. 5 (2007): 502-506.
© 2007 American Medical Association. All rights reserved.
Posted August 11, 2008.
References:
- Lee WY, Park JS, Noh SY, et al. C-reactive protein concentrations are related to insulin resistance and metabolic syndrome as defined by the ATP III report. Int J Cardiol. 2004;97:101-106.
- Sesso HD, Buring JE, Rifai N, Blake GJ, Gaziano JM, Ridker PM. C-reactive protein and the risk of developing hypertension. JAMA. 2003;290:2945-2951.
- Ridker PM, Buring JE, Cook NR, Rifai N. C-reactive protein, the metabolic syndrome, and risk of incident cardiovascular events: an 8-year follow-up of 14,719 initially healthy American women. Circulation. 2003;107:391-397.
- Wikipedia (metabolic syndrome).
- Esposito K, Giugliano D. Diet and inflammation: a link to metabolic and cardiovascular diseases. Eur Heart J. 2006;27:15-20.
- Your guide to lowering your blood pressure with DASH. National Heart Lung and Blood Institute website.
