Ascorbic acid availability from ascorbyl 2-polyphosphate and ascorbyl 2-sulfate in sea bass (Dicentrarchus labrax)

A trial with a total of 24 European sea bass (mean weight 337 +/- 75 g) was conducted to investigate the biological effects of two vitamin C sources, ascorbyl 2-polyphosphate (AP) and ascorbyl 2-sulfate (AS). The fish were held in fiberglass tanks at a density of four fish per tank in synthetic seawater with 17% salinity, a temperature of 20 degrees C and 8.2-11.2 mg 1(-1) dissolved oxygen. The sea bass were fed a vitamin C-free diet for 20 days before and 21 days after oral administration of the two sources of vitamin C as pills (2 pills, each containing 10 mg vitamin C). The placebo and two sources of vitamin C were assigned randomly to the tanks and administered by force feeding. To determine plasma ascorbic acid levels, a pre-experimental blood sample was taken 48 h before oral administration, then 5 h after forced feeding the vitamin C sources and on day 1, 2, 6, 8, 14 and 21 of the post-application period. At 48 h before forced feeding, a plasma L-ascorbic acid value of 3.1 mg 1(-1) was found. The highest concentration of plasma L-ascorbic acid for both sources of vitamin C was observed 5 h after force feeding (AP 20.7 mg 1(-1),IAS 8.3 mg 1(-1)). On day I, the level of plasma L-ascorbic acid started to decrease until the end of the experiment at day 21. The average plasma L-ascorbic acid level of fish fed AP was significantly higher than the value of fish fed ascorbyl 2-sulfate and the placebo. These results indicate that L-ascorbic acid is more rapidly adsorbed when administered as ascorbyl 2-polyphosphate and has a higher bioavailability than ascorbyl 2-sulfate in European sea bass. (C) 1998 Elsevier Science B.V.