Algae

For all intents and purposes algae is little more than pond scum or seaweed (seaweeds are large algae that grow in a saltwater or marine environment). Algae are very simple, chlorophyll-containing organisms, in a family of more than 20,000 different known species. That's a lot of scum and seaweed! A number of these have been used for drugs, where they can work as anticoagulants, antibiotics, antihypertensive agents, blood cholesterol reducers, dilatory agents, and insecticides. In cosmetics, algae are used as thickening agents, water-binding agents, and antioxidants. But some algae are also potential skin irritants. For example, the phycocyanin found in blue-green algae has been suspected of allergenicity or causing dermatitis on the basis of patch tests (Source: Current Issues in Molecular Biology, January 2002, pages 1-11). Other forms of algae, such as Irish moss and carrageenan, contain proteins, vitamin A, sugar, starch, vitamin B1, iron, sodium, phosphorus, magnesium, copper, and calcium. For the most part, algae, in their many forms, are probably less of a risk and more of a help to skin when used as antioxidants. But the claims that algae can stop or get rid of wrinkling are completely unsubstantiated.

Names of the algae typically found in cosmetics include Ulva lactuca, Ascophyllum, Laminaria longicruris, Laminaria saccharine, Laminaria digitata, Alaria esculenta, various Porphyra species, Chondrus crispus, and Mastocarpus stellatus. It is also listed plainly as "algae extract", though current CTFA (Cosmetics, Toiletries & Fragrance Association) regulations mandate that manufacturers list the specific type of algae each product contains.