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Nutr Metab (Lond). 2012 Feb 3;9:8. doi: 10.1186/1743-7075-9-8. Flaxseed dietary fibers lower cholesterol and increase fecal fat excretion, but magnitude of effect depend on food type.  Kristensen M, Jensen MG, Aarestrup J, Petersen KE, Søndergaard L, Mikkelsen MS, Astrup A.  Department of Human Nutrition, Faculty of Life Sciences, University of Copenhagen, Denmark. mekr@life.ku.dk.

BACKGROUND: Dietary fibers have been proposed to play a role in cardiovascular risk as well as body weight management. Flaxseeds are a good source of dietary fibers, and a large proportion of these are water-soluble viscous fibers.

METHOD: Here, we examine the effect of flaxseed dietary fibers in different food matrices on blood lipids and fecal excretion of fat and energy in a double-blind randomized crossover study with 17 subjects. Three different 7-d diets were tested: a low-fiber control diet (Control), a diet with flaxseed fiber drink (3/day) (Flax drink), and a diet with flaxseed fiber bread (3/day) (Flax bread). Total fat and energy excretion was measured in feces, blood samples were collected before and after each period, and appetite sensation registered 3 times daily before main meals.

RESULTS: Compared to control, Flax drink lowered fasting total-cholesterol and LDL-cholesterol by 12 and 15%, respectively, (p < 0.01), whereas Flax bread only produced a reduction of 7 and 9%, respectively (p < 0.05). Fecal fat and energy excretion increased by 50 and 23% with Flax drink consumption compared to control (p < 0.05), but only fecal fat excretion was increased with Flax bread compared to control (p < 0.05).

CONCLUSION: Both Flax drink and Flax bread resulted in decreased plasma total and LDL-cholesterol and increased fat excretion, but the food matrix and/or processing may be of importance. Viscous flaxseed dietary fibers may be a useful tool for lowering blood cholesterol and potentially play a role in energy balance.

TRIAL REGISTRATION:  ClinicalTrials.gov: NCT00953004.

PMID: 22305169