Six normal and five maturity-onset diabetic subjects were studied. On the first day, they received a control test meal after a 12-hour overnight fast. On the second day, the normal subjects and on the seventh day, the diabetics received the test meals with 3.9 g konjac mannan (glucomannan) respectively. The test meals with vitamins were prepared by adding 3000 r of vitamin B12 (mecobalamin, E1) and 500 mg of vitamin E (tocopherol acetate). Vitamin A (10000 units) was also given to the diabetic subjects with the test meals.
Venous blood samples were taken immediately before the test meal and again at 1, 3, 5, 8, 12 and 24 hours for analysis of vitamins.
The results showed that the absorption rates, of vitamins A and E in the intestine weae reduced when konjac mannan was added to the test meals, but that of vitamin B₁₂ was not.
It is suggested that konjac mannan reduced fat-soluble vitamin absorption removing bile acids, but not fat insoluble vitamin absorption intheintes.