Nutritional and Physiological Effects of Dietary Fiber in Oats and Barley

Abstract

Oats and barley are rich in water-soluble dietary fiber which is mainly composed of β-glucan. This study evaluates the nutritional and physiological effects of the water-soluble dietary fiber, cereal gum, in oats and barley from animal and human experiments.
Effect of the water-soluble dietary fiber in oats and barley on the lipid metabolism in rats
The effects of ingested oat and barley gum on the plasma and liver lipid levels were examined in genetically obese and lean Zucker rats. Obese and lean male Zucker rats, aged 6 weeks, were fed for 34 days on a standard diet or on diets corresponding to 2% total dietary fiber. Both the oat and barley gum suppressed the liver lipid accumulation and elevation of the plasma cholesterol level in obese rats. The results of this animal experiment indicate that ingested oat and barley gum ameliorated fatty liver and hypercholesterolemia in obese Zucker rats.
Effects of oat and barley gum on the lipid metabolism in rats
The effect of various amounts of oat and barley gum added to the diet on the plasma and liver lipid levels was examined in cholesterol-fed rats. Male Sprague-Dawley rats, aged 5 weeks, were fed for 9 days on a diet containing the oat or barley gum corresponding to 0%, 1%, 2%, or 4% soluble fiber. The plasma triglyceride, liver cholesterol, and liver triglyceride levels were lower in the rats fed on the diets containing 1-4% oat gum and 2-4% barley gum than in the rats fed on the gum-free diet. The diet containing 4% oat gum increased the fecal excretion of total lipids. The fecal excretion of acidic steroids was higher from the rats fed on the diets containing 2-4% oat gum and 1% barley gum than from the rats fed on the gum-free diet. The results of this experiment indicate that the minimum amounts of oat and barley gum, which acted as lipid-lowering compounds, were respectively 1% and 2% of fiber in the diet.
Effect of oatmeal supplementation on the serum cholesterol levels in men with boundary and mild hypercholesterolemia
We examined the effect of oatmeal containing β-glucan on blood lipids and the safety of its long-term intake in men with boundary and hypercholesterolemia. A total of 48 men with boundary and mild hypercholesterolemia were assigned to three groups. Each group A subject was given four pieces of placebo cookies once a day for 12 weeks, each group B subject was given test oatmeal cookies containing oatmeal at 30g/4 pieces, and each group C subject was given the same cookies containing oatmeal at 45g/4 pieces. The serum total cholesterol level for group C with boundary hypercholesterolemia was significantly lower than that for group A or group C (p<0.05). The results of this human trial indicate that supplementation with oatmeal at 45g/day (1.6g of β-glucan/day) decreased the serum total cholesterol level in men with boundary hypercholesterolemia.
Additional human trial with oatmeal porridge
An additional human trial with oatmeal porridge was examined; each subject in the oatmeal group was given oatmeal porridge containing 45g of oatmeal (1.6g of β-glucan) once a day for 12 weeks, and the control group subjects were given control porridge containing white rice and cellulose as the substitute for oatmeal. The level of serum total cholesterol in the oatmeal group was significantly lower than that in the control group throughout the ingestion period (p<0.05). This additional human trial indicates that oatmeal containing β-glucan could modulate the level of serum total cholesterol.
Effect of oatmeal supplementation on the serum cholesterol levels in adults with boundary and mild hypercholesterolemia
This study examined the effect of oatmeal on the serum cholesterol levels in Japanese adult men and women with boundary and mild hypercholesterolemia. Seventy-four men and nineteen women were randomly assigned to either the placebo or oatmeal group for