Effects of Dietary Fiber on the Bioavailability of Folic Acid Monoglutamate

Abstract

Low bioavailability of folacin has been previously reported for a variety of foods of plant origin. This study was conducted to examine the possible role of various types of dietary fiber on the bioavailability of folic acid monoglutamate. Cellulose, pectin, lignin, sodium alginate and wheat bran were selected for their differing physical and chemical properties. In vitro binding studies by equilibrium dialysis showed no evidence of physical or chemical binding of folic acid under physiological conditions. In vivo effects were evaluated by a chick bioassay with graded levels of folic acid in semipurified diets containing the fiber materials at 3% (weight/weight). Total liver and plasma folacin concentration and chick growth were used as response indicators. Dose-response curves indicated that pectin, lignin and alginate significantly reduced chick growth at all levels of dietary folacin. Plasma and liver folacin dose-response curves were not significantly different for any of the fiber materials, which indicated that the growth impairment was not due to a fiber effect on folic acid absorption. These results suggest that added dietary fiber has little or no effect on the bioavailability of folic acid monoglutamate.

Comparison of Conjugase Treatment Procedures in the Microbiological Assay for Food Folacin

“…These data suggest that long chain folacin polyglutamates were retained by the cellulosic filter paper. This finding concurs with results reported by Ristow et al (1982) that folic acid monoglutamate did not adsorb or bind to cellulosic materials. Quantitative data on the possible binding of various folate forms to fiber need to be established.…”

Application of in vitro bioaccessibility and bioavailability methods for calcium, carotenoids, folate, iron, magnesium, polyphenols, zinc, and vitamins B6, B12, D, and E

“…Similarly, microwaved chopped spinach led to higher plasma folate levels than microwaved whole spinach (van het Hof et al, 1999). Dietary fibers such as cellulose, lignin, pectin, sodium alginate, and wheat bran, appear not to affect folic acid bioavailability (Ristow et al, 1982). …”

Review: efficacy of alginate supplementation in relation to appetite regulation and metabolic risk factors: evidence from animal and human studies

“…The importance of physico‐chemical properties such as viscosity has been recognized to influence regulation of appetite and food intake . Compared to non‐viscous fibres (cellulose and wheat bran‐enriched diets), a diet containing 3% alginate significantly lowered growth performance in a 3‐week feeding trial with chickens . In later experiments, rats fed with an experimental diet containing 5% alginate exhibited lower body weight after 2 weeks and 4 weeks compared to rats fed with a non‐fibre control diet.…”