GASTRIC-ACIDITY INFLUENCES THE BLOOD RESPONSE TO A BETA-CAROTENE DOSEIN HUMANS

The effect of gastric acidity on the blood response to a single dose o f 120 mg beta-carotene in humans was investigated in 12 normal subject s (5 women, 7 men) aged 23-68 y. Omeprazole was used for 7 d to oblite rate gastric acid secretion and to raise gastric pH to > 4.5. In a cro ssover design, six subjects were randomly assigned to take beta-carote ne with omeprazole either at the beginning (day 9) or at the end (day 26) of the study. The beta-carotene response in blood was not altered by the experimental order. Results from the high-gastric-pH phase (ie, with omeprazole) were analyzed together and compared with the results from the low-gastric-pH phase (ie, without omeprazole). The increases of serum concentrations of both trans beta-carotene and cis beta-caro tene 6 and 24 h after the beta-carotene dose were significantly greate r at a low gastric pH (pH = 1.3 +/- 0.1, ie, without omeprazole) than those at a high gastric pH (pH = 6.4 +/- 0.3, ie, with omeprazole), P < 0.02. Similarly, 24 h after beta-carotene administration, the area u nder the blood beta-carotene response curve (trans plus cis beta carot ene) was significantly greater at a low gastric pH (6825 +/- 760 nmol . h/L) than at a high gastric pH (3390 +/- 550 nmol . h/L), P < 0.002. In investigations of bacterial overgrowth, gelatin capsule disintegra tion and isomeric profiles associated with high and low pH, we could n ot identify factors to explain the differences observed in the blood r esponse curves between low-gastric-pH and high-gastric-pH conditions. A suppressed blood response of beta-carotene at a high intraluminal pH may have been due to the slower movement of negatively charged micell es through the unstirred water layer and cell membrane.