Psyllium husk fibre supplementation to soybean and coconut oil diets of humans: effect on fat digestibility and faecal fatty acid excretion.

The effects of psyllium fibre supplementation to polyunsaturated fatty acid rich soybean oil and saturated fatty acid rich coconut oil diets on fat digestibility and faecal fatty acid excretion were investigated in healthy humans. The study consisted of four 7-day experimental periods. Participants consumed soybean oil (SO), soybean oil plus psyllium fibre (20 g/day) (SO+PF), coconut oil (CO) and coconut oil plus psyllium fibre (20 g/day) (CO+PF) diets. Laboratory diet provided 30% calories from fat (20% from test oils and 10% from basal diet), 15% calories from protein and 55% calories from carbohydrate. Fat digestibility was significantly lower and faecal fat excretion was significantly higher with SO+PF diet than SO diet and with CO+PF diet than CO diet. Faecal excretion of myristic and lauric acids was not affected by test diets. Percent faecal palmitic acid excretion was significantly higher during psyllium supplementation periods. Higher faecal linoleic acid excretion was observed with soybean oil diets compared with coconut oil diets. Increased faecal fat loss, decreased fat digestibility and increased faecal palmitic acid excretion with psyllium supplementation may partly explain the hypocholesterolaemic action of psyllium fibre.