Possible Interaction: Quercetin and Beta Carotene

“Furthermore, quercetin , naringenin, and alpha-tocopherol partly suppressed the pro-inflammatory effects of 20 microM beta-carotene on PMA-stimulated HL-60 cells, and the suppressing effects of quercetin and naringenin were better than or similar to those of alpha-tocopherol.”

“Our results urge consideration of the safety of beta-carotene supplementation concerning effects on inflammation and suggest that the interaction between beta-carotene and quercetin or naringenin may alter the effects of beta-carotene on the secretion of pro-inflammatory mediators.”

“ Quercetin also additively or synergistically enhanced the inhibitory effects of 2 microM beta-carotene on the secretion of pro-inflammatory mediators and the DNA-damaging ability of PMA-stimulated HL-60 cells.”

“ Quercetin increased the safety of high doses of beta-carotene , possibly through interaction with beta-carotene's oxidative products or through inhibition of CYP1A2 expression.”

“ Quercetin significantly inhibited the DNA strand breaks and the increase in CYP1A2 protein induced by AC or beta-carotene in combination with BaP or by AC alone.”

“These in vitro results suggest that a combination of beta-carotene with naringin, rutin, or quercetin may increase the safety of beta-carotene.”

“These results demonstrate that quercetin can suppress the conversion of beta-carotene which develops in the cytosol of small intestinal epithelial cells, and that rutin whose rutinose-moiety prevents being absorbed in the small intestine cannot suppress the conversion in vivo.”

“When the conversion of beta-carotene by a preparation of the murine small intestine was measured in vitro, the addition of quercetin or rutin considerably inhibited the conversion.”

“When the levels of hepatic beta-carotene and retinoids were … three groups of mice fed a diet supplemented with beta-carotene … quercetin or rutin or beta-carotene alone (four to six mice per group), quercetin increased … of beta-carotene and decreased the level of retinol, whereas rutin did not.”

“Taken together, this cell culture study demonstrates an interaction between flavonoids and beta-carotene in UVA-induced DNA damage, and the results suggest that a combination of beta-carotene with naringin, rutin or quercetin may increase the safety of beta-carotene.”