Effect of a high-fiber diet vs a fiber-supplemented diet on C-reactive protein level

Diets high in fiber are associated with lower levels of inflammatory markers. This study examined the reduction in inflammation from a diet supplemented with fiber compared with a diet naturally high in fiber.

Randomized crossover intervention trial of 2 diets, a high-fiber (30-g/d) Dietary Approaches to Stop Hypertension (DASH) diet or fiber-supplemented diet (30 g/d), after a baseline (regular) diet period of 3 weeks. There were 35 participants (18 lean normotensive and 17 obese hypertensive individuals) aged 18 to 49 years.

The study included 28 women and 7 men; 16 (46%) were black, the remainder white. The mean (SD) fiber intake on baseline diets was 11.9 (0.3) g/d; on the high-fiber DASH diet, 27.7 (0.6) g/d; and on the supplemented diet, 26.3 (0.4) g/d. Overall, the mean C-reactive protein (CRP) level changed from 4.4 to 3.8 mg/L (-13.7%; P = .046) in the high-fiber DASH diet group and to 3.6 mg/L (-18.1%) in the fiber-supplemented diet group (P = .03). However, CRP levels decreased in the 18 lean normotensive participants in either intervention diet group (2.0 mg/L [baseline] vs 1.4 mg/L [high-fiber DASH] vs 1.2 mg/L [supplemented]); P<.05) but did not change significantly (7.1 mg/L [baseline] vs 6.2 mg/L [high-fiber DASH] vs 6.5 mg/L [supplemented]; P>.05) in obese hypertensive participants. Neither age nor race influenced the response of CRP levels to the diets. No evidence of a crossover effect was detected.

The results demonstrate that fiber intake of about 30 g/d) from a diet naturally rich in fiber or from a supplement can reduce levels of CRP. Further research is needed to more clearly elucidate the differential effect seen in lean vs obese individuals and whether modification of dietary fiber may be helpful in modulating inflammation and its consequent cardiovascular consequences.