The nutritive value of algae has some interesting aspects. Generally, the protein content is high and the uptake by humans can be enhanced by boiling, frying, roasting or deep-freezing. There are opinions that the carbohydrates can be made more readily available after consumed algae for some time and there has developed an intestinal bacterial flora which helps the uptake.
Certain green and red algae contain unsaturated fatty acids and tests on rats have shown that when added to the diet the blood cholesterol levels were lowered.
Algae have a relatively low energy content but they can contribute a valuable supplements of minerals, trace elements and vitamins, necessary for humans.
For instance, the content of calcium in Ulva and Laminaria is 4-8 times higher than in soy beans and milk. Iron, copper, manganese, iodine, selenium and zinc are trace elements which are important for humans. The content of iron in Ulva and Enteromorpha is 20-30 times higher than in beef and spinach. Algae contain all the minerals necessary human well-being and are also rich in vitamins (A, B1, B2, B6, B12, C, D, E and K). For example, Porphyra has twenty times more vitamin A and ten times more Niacin than spinach, and has also forty times more vitamin B2 and the same level of vitamin C as tomato. Algae also are rich in B12 and folic acid.