The nutritional consequences of algae consumption in young populations consuming hypercholesterolaemic diets have hardly been investigated. This study tests the effect of algae supplementation of cholesterol-enriched balanced diets on growth, dietary efficiency ratio, mineral intake and absorption, organ weight and structure and cholesterolaemia in growing Wistar rats. Three groups of ten rats each were fed for 3 weeks with experimental diets containing 93 % casein-soyabean oil base with 2·4 % cholesterol-raising agent and 7 % supplement. The control group received cellulose (35 %), group 2 consumed Nori (33·8 % fibre) and group 3 consumed Konbu (36·1 % fibre). Food intake and body weight gain were not significantly affected. Algae groups presented significantly higher dietary efficiency ratio values than control rats. Apparent absorption of several minerals appeared significantly affected, mainly in Nori-fed rats, with a significant decrease in the ratio of Zn and Cu intakes and apparent absorption. Nori diet significantly decreased plasma cholesterol. Algae supplement did not significantly affect organ size and structure. Control and Konbu rats showed severe liver fat infiltration, while Nori rats exhibited a significantly lower degree of lipid-like hepatocyte vacuolization but light to moderate leukocyte infiltration. Light to moderate scaling off of the epithelium and moderate submucosa oedema was observed in all groups. Although long-term studies are needed to check the possible extrapolation of these data to human subjects, it can be concluded that a Nori, but not a Konbu, dietary supplement reverses the negative effect of dietary cholesterol intake and also appears to be related to mineral availability in growing subjects.