Are your patients with risk of CVD getting the viscous soluble fiber they need?

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Applied Evidence

Are your patients with risk of CVD getting the viscous soluble fiber they need?

J Fam Pract. 2006 September;55(9):761-768

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References

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18. Brown L, Rosner B, Willett WW, et al. Cholesterol-lowering effects of dietary fiber: a meta-analysis. Am J Clin Nutr 1999;69:30-42.

19. Olson BH, Anderson SM, Becker MP, et al. Psyllium-enriched cereals lower blood total cholesterol and LDL cholesterol, but not HDL cholesterol, in hypercholesterolemic adults: results of a meta-analysis. J Nutr 1997;127:1973-1980.

20. Anderson JW, Allgood LD, Lawrence A, et al. Cholesterol-lowering effects of psyllium intake adjunctive to diet therapy in men and women with hypercholesterolemia: meta-analysis of 8 controlled trials. Am J Clin Nutr 2000;71:472-479.

21. Davidson MH, Dugan LD, Burns JH, et al. The hypocholesterolemic effects of beta-glucan in oatmeal and oat bran. A dose controlled study. JAMA 1991;265:1833-1839.

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For those on lipid-lowering drug therapy, supplementation with viscous fiber may help achieve the recommended reduction in LDL-C with lower doses of drugs.²⁵ Moreyra et al²⁵ treated hypercholesterolemic adults with 20 mg of simvastatin plus placebo, 10 mg of simvastatin plus placebo, or 10 mg of simvastatin plus 15 g of psyllium. A significant LDL-C reduction (36%) was observed in the group receiving 10 mg of simvastatin plus psyllium and 20 mg of simvastatin. The authors concluded that psyllium supplementation augmented the lipid-lowering effects of the statin.

Blood pressure decreases, as does the need for medications. In a prospective study of 51,529 male health professionals followed for 5 years, Ascherio et al²⁶ found an inverse association between incidence of hypertension and fruit fiber intake in young men, independent of age and other risk factors. Moderate but significant reductions in 24-hour monitored systolic blood pressure—by 5.9 mm Hg after psyllium²⁷ and by 5 mm Hg after oat administration²⁸—were reported in randomized controlled trials. A 5 mm Hg reduction of systolic blood pressure in the population would result in a 9% reduction in fatal CHD and a 7% decrease in all-cause mortality.²⁹

Eighty-eight patients with a history of essential moderate hypertension treated with medications were randomized to consume 5.4 g/d of beta-glucan in oats or placebo for 12 weeks. Oat consumption reduced the need for blood pressure medications in 73% of participants in the treatment group, compared with 42% in the control group.³⁰

FAST TRACK

Foods rich in viscous soluble fiber can reduce LDL cholesterol levels, improve insulin sensitivity, and decrease blood pressure

The Seventh Report of the Joint National Committee on Prevention, Detection, Evaluation, and Treatment of High Blood Pressure recommends a dietary plan rich in fiber (24 g/1600 kcal/d) from fruits and vegetables among other life style modifications to treat hypertension.²⁹

Insulin sensitivity improves and HbA_1c drops. Foods rich in viscous soluble fiber lower glycemic index compared with reference food in healthy people and in patients with type II diabetes.^31,32 In a randomized trial, barley meal enriched with 1.5 to 15 g of viscous soluble fiber reduced postprandial glucose concentration by 19% to 28% compared with wheat bread, and by 15% to 30% compared with glucose solution.³¹ Consumption of barley meal containing 3.5 g of soluble viscous fiber improved insulin sensitivity as assessed by the standard oral glucose tolerance test; it significantly reduced fasting insulin by 11.5% and postprandial increase in plasma glucose levels by 8.3%, and increased glucose disappearance by 7.5%.³³

FAST TRACK

80% of the fiber in a typical diet is insoluble; viscous soluble fiber is found in whole-grain cereals, fruits, beans, and psyllium seeds

In patients with diabetes, postprandial glucose was significantly less by 10.6% after a meal of barley bread compared with control wheat bread.³² Intake of barley bread with 5.2 g of viscous soluble fiber for 12 weeks resulted in 20% reduced postprandial glucose response and in decreased doses of oral hypoglycemic medications.³⁴

In a meta-analysis of 12 clinical trials, diets moderate in carbohydrate intake with increased consumption of foods rich in fiber provided the best control of fasting blood glucose and a significant decrease in glycosylated hemoglobin (HbA_1c) in patients with diabetes.³⁵

TABLE 2
Viscous soluble fiber reduces LDL-cholesterol (results of RCTs)

STUDY POPULATION	VISCOUS SOLUBLE FIBER SOURCE	DOSE (G/D)	LDL-C REDUCTION (%) MEAN (95% CI)	ESTIMATED CVD EVENT REDUCTION (%) MEAN (95% CI)
Hypercholesterolemic men and women (656)¹⁹	Psyllium	10	7 (5-9)	7 (5-9)
Hypercholesterolemic men (404)²⁰	Psyllium	3–12	9 (7-10)	9 (7-10)
Hypercholesterolemic men and women (150)²¹	Oat*	1.2–6	16 (14-25)	16 (14-25)
Healthy men and women (236)²²	Oat*	2.2	8 (2-13)	8 (2-13)
Healthy men and women (208)²³	Oat*	2.4–3.3	5	5 (3-7)
Healthy men and women (245)²⁴	Oat*	2.4	9	9 (5-12)
*The dose of beta-glucan in oats.

CVD events decline with soluble-fiber diets, and diverse fiber sources yield equivalent effects

TABLE 3 summarizes findings from prospective observational studies of adults followed for more than 5 years to evaluate the incidence of CVD in groups consuming different kinds of dietary fiber. These studies show that risk reduction is consistent in different populations and with different sources of dietary fiber,^4,36-38 regardless of patient age, gender, treatment status, smoking, and other risk factors for CVD.

In a pooled analysis of 10 large cohort studies, an additional intake of 10 g/d of fruit fiber reduced the risk of CHD death by 30%.⁴

The Women’s Health Study followed health professionals for 6 years and reported that an increase of 4.9 g/d of viscous soluble fiber was associated with a 44% reduction in myocardial infarction incidents.³⁸

Among participants in the National Health and Nutrition Examination Survey (NHANES) I Follow-up Study, each 5 g/d increase in viscous soluble fiber intake diminished the risk of CVD by 6% and coronary heart disease by 8%.³⁷