Quote from dan on July 17, 2020, 6:37 pm

"Compared with the serum response from beta-carotene supplements, the bioavailability of beta-carotene from various foods is as follows: stir-fried vegetables, 7%; carrots, 18–26%; and spinach, 7%."

"A subsequent study in Indonesia found the serum response of beta-carotene from fruits to be four times that from vegetables.  The low bioavailability of carotenoids from dark-green leafy vegetables may be attributed to entrapment and complexing to proteins in chloroplasts and within cell structures."

"In orange and yellow fruits (mango, papaya, etc) and in pumpkin and sweet potato, carotenoids are dissolved in oil droplets in chromoplasts and can be readily extracted during digestion. "

"Cooking increases the bioavailability of carotenoids, possibly because of the softening or disruption of plant cell walls and the disruption of carotenoid-protein complexes.  Stahl & Sies reported that lycopene concentrations in human serum increased from processed but not unprocessed tomato juice. Bioavailability of lycopene was greater from tomato paste than from fresh tomatoes."

"The absorption and bioconversion of beta-carotene is markedly reduced when the intake of fat is low."

"Some data suggest that polyunsaturated fatty acid–rich dietary fat increases the serum response to beta-carotene more than does mono-unsaturated fatty acid– rich dietary fat"

--Bioavailability and Bioconversion of Carotenoids, https://sci-hub.tw/10.1146/annurev.nutr.18.1.19

 

"Studies in Western populations have found that the bioavailability of carotenoids was lower than expected from vegetables such as carrots and broccoli."

"In our recent study of breast-feeding women in Indonesia, we found no improvement in serum concentrations of beta-carotene and retinol after they consumed dark-green, leafy vegetables and carrots. However, there was a marked increase in both indexes after they consumed a wafer enriched with the same amount of beta-carotene as in the vegetables."

"This study indicated that in anemic children with a marginal vitamin A status, the mean apparent effectiveness of fruit in improving vitamin A status was 50%, and of dark-green, leafy vegetables and carrots was 23%, of what has been assumed up until now."

--Orange fruit is more effective than are dark-green, leafy vegetables in increasing serum concentrations of retinol and beta-carotene in schoolchildren in Indonesia https://pubmed.ncbi.nlm.nih.gov/9808223/