A high-fiber diet does not cause mineral and nutrient deficiencies.

We evaluated the hypothesis that a healthy population taking a high-fiber diet may develop deficiencies of various minerals and nutrients in three groups of healthy subjects: 1) sixty-eight people regularly supplementing their diet with at least 2 tablespoons of bran for at least 6 months (mean 3 tablespoons for 13 months); 2) forty-three controls not consuming bran supplements; and 3) twenty vegetarians (eight of them consuming bran supplements) who had a very high fiber consumption for many years. The mean serum levels of iron, total iron binding capacity, calcium, phosphorus, alkaline phosphatase, zinc, magnesium, vitamin A, and cholesterol were within the normal range in all the three groups. In the bran eaters, vitamin A was higher, and alkaline phosphatase and magnesium lower than in the other two groups. In the vegetarians, the phosphorus level was higher and cholesterol and iron binding capacity lower than in the other two groups. There was no correlation between the amount of bran consumed and the blood level of nutrients. The fiber consumption of the vegetarians was very high, more than three times that of the controls. Our study indicates that a moderately or even extremely high consumption of fiber for a long time does not by itself cause mineral or nutrient deficiencies in a western type population.