Fermentable dietary fibers elevate urinary methylmalonate and decrease propionate oxidation in rats deprived of...

Area of Science:

• Biochemistry
• Nutrition Science
• Animal Nutrition

Background:

• Vitamin B-12 deficiency presents with specific biochemical markers.
• Dietary fiber intake can influence gut microbiota and metabolism.
• The interaction between fiber fermentability and vitamin B-12 metabolism is not fully understood.

Purpose of the Study:

• To investigate the impact of dietary fiber fermentability on vitamin B-12 deficiency indicators in rats.
• To compare the effects of poorly fermentable versus highly fermentable fibers on biochemical markers of B-12 status.
• To explore the potential role of bacterial propionate production in mediating these effects.

Main Methods:

• Rats were fed a vitamin B-12 deficient diet supplemented with different types of dietary fiber (cellulose, lignin, alginic acid, pectin, guar gum, xylan).
• Biochemical indicators of vitamin B-12 status were assessed, including urinary methylmalonic acid levels and [14C]propionate oxidation.
• Apparent vitamin B-12 status was evaluated based on these biochemical markers.

Main Results:

• Highly fermentable fibers (pectin, guar gum, xylan) significantly increased urinary methylmalonic acid and decreased [14C]propionate oxidation.
• Poorly fermentable fibers (cellulose, lignin, alginic acid) had no significant impact on vitamin B-12 status indicators.
• Pectin demonstrated a more pronounced effect compared to guar gum and xylan, suggesting dose-dependent or specific fiber properties.

Conclusions:

• Fermentable dietary fibers may exacerbate biochemical indicators of vitamin B-12 deficiency, potentially by stimulating bacterial propionate production.
• The degree of fiber fermentability is a critical factor in this interaction.
• Pectin's significant effect warrants further investigation into its potential interference with vitamin B-12 absorption.