No effect of pH on in vitro digestion of carotenoids from sweet potatoes and mandarin oranges

Abstract

Beta‐carotene (BC) and beta‐cryptoxanthin (CX) can form vitamin A physiologically. Recent observational studies suggest that CX has greater bioavailability than BC from most diets. This means that CX‐rich foods such as mandarin oranges might be better than expected sources of vitamin A. We hypothesized that CX was more easily digested from its major food sources, possibly because these foods are acidic. We used a static in vitro digestion model to compare the apparent bioavailability of CX from mandarin oranges to BC from orange‐fleshed sweet potatoes (OFSP) at several physiological pHs. The model included saliva, gastric fluid, duodenal fluid, and bile components. BC and CX concentrations were measured by reversed‐phase HPLC or by spectrophotometry at 450 nm. BC from both varieties of boiled OFSP had very low bioavailability (0.65 – 1.08%), comparable to those reported for OFSP without fat in the literature. CX from mandarin oranges had approximately 3X better bioavailability (2.21 – 4.25%). Changes in saliva, gastric, and bile fluid pH did not change bioavailability significantly for either mandarin oranges or OFSP. Our results support the hypothesis that CX is more bioavailable from a major food source (mandarin oranges) than BC is from orange‐fleshed sweet potatoes (OFSP), a common intervention food used to increase VA status. Research was supported by USDA ARS in‐house funds.