Iron status and dietary levels of iron affect the bioavailability of haem and nonhaem iron in Atlantic salmon Salmo salar

The absorption of haem iron and nonhaem iron in 155‐g Atlantic salmon Salmo salar was studied by simultaneous labelling of the two forms of iron with 59Fe or 55Fe, respectively. Iron absorption was measured after incorporation of this element into blood and tissue 2 days after oral administration. Fish with a low iron status showed a significantly greater absorption of both haem and nonhaem iron than iron‐loaded fish. The low‐iron group distributed a larger proportion of the iron to kidney and spleen than the iron‐loaded or control fish. Absorption of both forms of iron increased with higher doses administered, but absorption relative to dose administered decreased. There was a trend suggesting that increased levels of dietary haem iron resulted in the reduced uptake of nonhaem iron, but not vice versa. The results of the present study suggest that factors affecting bioavailability of haem and nonhaem iron in Atlantic salmon are similar to those of other vertebrates.