Ulva rigida is an excellent source of nutrients and could improve a balanced diet. Further studies are required to research the potential of the seaweed as a natural source of bioactive compounds.

The influence of pinealectomy on serotonin cerebral metabolism was examined in male rats maintained in a long photoperiod (14 h L:10 h D). Eight weeks after pinealectomy, serum, hepatic and CNS concentrations of tryptophan were not affected. The concentrations of 5-HT was significantly decreased in only three regions, hypothalamus, midbrain and hippocampus. The levels of 5-HIAA decreased significantly only in the hypothalamus and the midbrain. These results suggest that pinealectomy promotes a decreased hypothalamic and midbrain 5-HT utilization.

Both seaweeds are a good source of protein and carbohydrates and contain all essential amino acids. The effects of the two algae on enzyme activities were similar. The inhibition of intestinal disaccharidase activity by seaweed ingestion could be interesting in patients with altered glucose homeostasis.

The use of seaweeds as a food is more widespread in Eastern than in Western countries, although demand for these plants has increased in the West because their possible usefulness as dietary supplements. However, very little is known about the effects of regular consumption of algae. The aim of the present study was to determine the composition of Ulva rigida and to evaluate the effects of dietary supplementation of the diet with 10% alga for 4 weeks on dietary intake, growth, protein efficiency ratio, diet conversion ratio, and some organ weights in growing male rats. We also studied the effect of inclusion of the alga in the diet on intestinal, hepatic, and renal enzymatic activities. U. rigida was found to be a good source of protein and carbohydrates. Food intake was higher in the U. rigida group than in the control group, but ingestion of alga did not have any effect on the other trophic parameters. The intestinal disaccharidase and leucine aminopeptidase activities were lower in rats fed with alga than in control rats, but γ-glutamyl transpeptidase activity was higher in the kidneys of alga-fed rats than in control rats. U. rigida contains high amounts of protein, carbohydrates, vitamins, and minerals and low amounts of lipids. Analysis of the amino acid composition revealed good-quality protein. The addition of alga to the diet inhibited disaccharidase activities, which suggested that alga consumption could be useful in some chronic disorders associated with pertubations of glucose homeostasis caused by carbohydrate absorption.

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