A review concerning nutritional and physiological properties of edible seaweeds is presented. Seaweeds are traditionally consumed in Asia as sea vegetables, but in Western countries they have been used as sources of gelling or thickening agents. From a nutritional point of view, they are low-calorie foods, with a high concentration of minerals (Mg, Ca, P, K and I), vitamins, proteins and undigestible carbohydrates, and a low content in lipids. Quality of protein and lipid in seaweeds is acceptable comparing with other diet vegetables mainly due to their high content in essential amino acids and their relative high levels of unsaturated fatty acids. Dietary fiber content range from 33% to 75% of dry weight, and mainly consist of soluble polysaccharides (range from 17% to 59%). Seaweeds constitute a source of dietary fiber that differ chemically and physicochemically from those of land plants and thus may induce different physiological effects. Referenced data indicate that algal dietary fiber may show important functional activities, such as antioxidant, antimutagenic and anticoagulant effect, antitumor activity, and an important role in the modification of lipid metabolism in human body. In conclusion, seaweeds have a high nutritional value, therefore an increase in their consumption, would elevate the foods offer to population.