Metabolic effects of dietary pungent spices on the gut in animal models

Abstract Text:

Beneficial influence of pungent spices was examined in experimental rats on: (i) fluidity of intestinal brush border membrane (BBM), (ii) activity of intestinal membrane bound enzymes, and (iii) ultra structural alterations in the intestinal epithelium. Groups of Wistar rats were maintained on dietary black pepper (0.5%), red pepper (3.0%), ginger (0.05%) and spice bioactive compounds– piperine (0.02%) and capsaicin (0.01%) for 8 weeks. Membrane fluidity study using an apolar fluorescent probe showed increased BBM fluidity in all the spice fed animals. This was corroborated by decreased cholesterol: phospholipid ratio in jejunal and ileal regions of the intestine. These dietary spices stimulated the activities of BBM enzymes─ glycyl-glycine dipeptidase, leucine amino peptidase and γ-glutamyl transpeptidase in jejunal mucosa, suggesting a modulation in membrane dynamics due to the apolar spice bioactive compounds interacting with surrounding lipids and hydrophobic portions in the protein vicinity. Scanning electron microscopy of the intestinal villi in these spice treatments revealed alteration in the ultra structure, especially an increase in microvilli length and perimeter which would mean a beneficial increase in the absorptive surface of the small intestine, providing for an increased bioavailability of micronutrients. Thus, dietary spices─ black pepper, red pepper and ginger were evidenced to induce alteration in BBM fluidity and passive permeability property, associated with the induction in the increased microvilli length and perimeter, resulting in increased absorptive surface of the small intestine.

 

     Everted segments of duodenum, jejunum and ileum portions of small intestines isolated from rats fed piperine, capsaicin and ginger containing diets for 8 weeks were examined for ex vivo uptake of iron, zinc and calcium from incubations containing digesta of finger millet.  Higher uptake of iron, zinc and calcium by the intestinal segments from spice-fed animals was observed. The increase in the mineral uptake was the highest for calcium with >100%. Higher in vitro absorption of β-carotene in the intestines was evidenced in all spice-fed animals. Dietary piperine and ginger increased the uptake of β-carotene by 147 and 98%, respectively,. while increase in absorption was 59 and 27% in black pepper and red pepper fed animals, respectively. Animal study conducted to evaluate the influence of dietary spice compounds - piperine, capsaicin and ginger on the absorption of orally administered β-carotene and its conversion to vitamin-A revealed significantly increased β-carotene concentration in serum, liver and intestine of piperine and ginger fed rats suggesting improved absorption of β-carotene. Retinol concentration was not however changed in these animals suggesting that bioconversion of β-carotene to vitamin-A was not similarly influenced. The higher intestinal uptake of iron, zinc, and β-carotene as a result of consumption of pungent spices could encourage a strategy to reduce deficiency of these micronutrients prevalent in population dependent on plant based foods.

Keywords: gut health, nutrient absorption, spices