Background: Previous studies revealed hepatic interactions of beta-carotene with alcohol in non-human primates, but bile carotenoids and alpha-tocopherol have not previously been explored in man.
Methods: To compare the plasma and biliary concentrations of carotenoids, retinoids and tocopherols among controls and patients with biliary and pancreatic diseases, these compounds were measured by high performance liquid chromatography in bile collected during 41 endoscopic retrograde cholangiopancreatographies.
Results: In 14 subjects with normal endoscopic retrograde cholangiopancreatography (controls), bile contained beta-carotene, alpha-carotene, lycopene, cryptoxanthin, lutein+zeaxanthin (23.9 +/- 6.6, 3.9 +/- 1.1, 39.9 +/- 21.6, 22.5 +/- 4.6, 217.1 +/- 27.8 nmol/l, respectively) with corresponding plasma values of 399.7 +/- 72.6, 88.5 +/- 18.8, 588.2 +/- 75.0, 145.1 +/- 25.9, 319.3 +/- 33.7 nmol/l. In 13 patients in whom bile duct stones impaired biliary excretion (as reflected by raised serum bilirubin), beta-carotene was significantly decreased in both plasma (199.6 +/- 35.5 nmol/l) and bile (9.4 +/- 2.0 nmol/l), with a similar trend for other carotenoids. The beta-carotene plasma/bile ratio was maintained, as well as a correlation between the two (r = 0.56; p = 0.048). Furthermore, in three subjects with complete biliary obstruction, plasma beta-carotene (35.8 +/- 20.2 nmol/l) decreased even more, probably reflecting malabsorption. In 11 patients with pancreatic diseases, plasma and bile beta-carotene were 107.9 +/- 17.8 and 6.6 +/- 2.0 nmol/l respectively, while a correlation between the two (r = 0.70; p = 0.018) again persisted, confirming the role of plasma beta-carotene in determining bile concentrations. Indeed, for the entire group (n = 41), the correlation between plasma and bile or red blood cell beta-carotene was highly significant, whereas plasma/red blood cell ratios remained unchanged. Similar findings were observed for alpha-tocopherol, with 8.4 +/- 0.9 mumol/l in control bile (vs. 23.2 +/- 1.7 mumol/l in plasma), and no significant change in the various groups.
Conclusions: 1) Carotenoids and tocopherols undergo biliary excretion in man. 2) Biliary concentrations reflect plasma levels in both normal and pathologic states. 3) Decreased biliary excretion of carotenoids does not increase plasma concentrations.