Effects of flax fiber on laxation and glycemic response in healthy volunteers.

We investigated whether a flax supplement taken orally or baked in a bakery product would effect the physiological responses characteristic of soluble and insoluble fiber, i.e., laxation and glycemic response, respectively. In Study 1, 26 healthy young adults consumed up to 15 g of fiber from a proprietary flax fiber supplement or as a psyllium supplement for 2 weeks once usual fecal weights were established. Changes in dietary fiber intake and acceptability of both products were evaluated. An increase in fecal weight was found with both fiber treatments. Supplemental fiber at intakes of 9.0 g/day (flax) and 10.4 g/day (psyllium) gave fecal bulking capacity of about 2.9 and 4.8 g of fecal weight/g of fiber, respectively. In Study 2, the effect of flax bread versus control white bread on glycemic response was studied. Eleven fasting subjects completed four test periods (duplicate trials of each bread) under standardized glycemic testing conditions. Paired t tests were used to analyze test compared with control peak blood glucose values (6.6 +/- 0.9 mmol/L compared with 6.9 +/- 0.7 mmol/L, P < .05, respectively) and area under the curve (AUC) (669 +/- 53 compared with 693 +/- 57, P = .015, respectively). Peak blood glucose values and AUC were improved by ingestion of flax fiber in healthy subjects. In conclusion, a flax fiber supplement provides the benefits of soluble and insoluble fiber.