Absorption of ascorbic acid and ascorbic sulfate and ascorbate metabolism in common carp (Cyprinus carpio L.)

Area of Science:

• Comparative physiology
• Fish nutrition
• Biochemistry

Background:

• Ascorbic acid (AA), or vitamin C, is essential for many organisms.
• Ascorbic sulfate (AS) is a potential alternative form of vitamin C.
• Understanding ascorbate metabolism in fish is crucial for aquaculture and health.

Purpose of the Study:

• To investigate the absorption and utilization of dietary ascorbic acid (AA) and ascorbic sulfate (AS) in common carp.
• To determine the primary sites of ascorbate absorption within the carp digestive tract.
• To assess the potential of AS as a vitamin C source for cyprinid fish.

Main Methods:

• Analysis of AA and AS in digestive tract contents of carp fed different diets (control, AA-supplemented, AS-supplemented).
• Measurement of ascorbate concentrations in various tissues (plasma, hepatopancreas, kidney, intestine, spleen, brain).
• Estimation of ascorbate catabolic rates in fasting and scorbutic-diet-fed fish.

Main Results:

• The anterior intestine (first 20%) was the major site of dietary AA absorption (58.7%), with 94.3% absorption in the whole gut.
• Significant AA concentrations were found in tissues of fish fed AA-supplemented diets, indicating effective utilization.
• AS was not absorbed from the intestine, and its presence in tissues was minimal, suggesting ineffective hydrolysis and utilization.

Conclusions:

• Common carp primarily absorb and utilize dietary ascorbic acid (AA) from the anterior intestine.
• Ascorbic sulfate (AS) is poorly absorbed and not effectively utilized as a vitamin C source by cyprinid fish.
• Cyprinid fish, like scurvy-prone mammals, appear unable to efficiently convert AS to functional vitamin C.