Seaweed is a loose colloquial term encompassing macroscopic, multicellular, marine algae, examples include red, brown and green algae. Seaweed contains a thallus, the algal body. This thallus has a flattened leaf-like structure called lamina, a spore cluster, float-assist organs, a stem-like structure, holdfast (for attachment to a surface) and haptera (for anchoring). Seaweed environmental requirements are seawater, light for photosynthesis, and a firm attachment point. Thus, seaweed is frequently found on rocky shores. Seaweeds have different types - cyanobacteria (the blue-green algae), Chlorophyta (the green algae), Phaeophyta (the brown algae) and Rhodophyta (the red seaweeds). The blue-green algae and green algae are found nearest the shore in shallow waters, they are in the forms of threadlike filaments, irregular sheets or branching fronds. The brown algae also have chlorophyll, but its brown pigment masks the green color. The red seaweeds are fernlike and exist in deep waters. Seaweeds reproduce in different ways. Lower types reproduce asexually, advanced types reproduce via motile zoospores or gametes. Pieces of a seaweed break off and may form a new plant. Seaweed Uses and Health Benefits Seaweeds are consumed by coastal people as food, particularly in East Asia. Sheets of dried Porphyra, a red algae, are used in soups, or to wrap sushi - Nori (海苔), Zicai (紫菜), and Gim (김). Seaweed is also used in beverage and some other kinds of foods. Seaweeds are also cultivated for the production of alginate, agar and carrageenan. These are hydrocolloids, they have gelling, water-retention and emulsifyig properties and they are popularly used in food industry. Seaweed is a source of iodine, iodine is needed for thyroid function and to prevent goitre. Seaweed is also a good source of potassium. Seaweed is also thought to benefit people suffered from tuberculosis, arthritis, colds and influenza, worm infestations and even tumors. Most health benefit claims have insufficient scientific supports. However, some studies do show seaweed has certain types of health benefits. _____________________________________________________________________________________________ The "Green Seaweeds" (Green Algae, Chlorophyta) Reviews Cholorphyta is the phylum (division) of the kingdom Protista consisting the green algae. The green algae have different species, which can be unicellular or multicellular. Those that are motile have flagella. Cells of the Chlorophyta contain chloroplasts for photosynthesis to occur. This phylum has an important class - Chlorophyceae. The class includes unicellular organisms such as Chlorella. Chlorella is a popular health dietary supplement. Chlorella is spherical in shape, about 2 to 10 μm in diameter, and is without flagella. Chlorella contains the green photosynthetic pigments chlorophyll-a and -b in its chloroplast. Through photosynthesis, chlorella multiplies rapidly. Chlorella is marketed as a supplement for weight control, cancer prevention, and immune system support. Chlorella is high in protein and other essential nutrients; when dried, it is about 45% protein, 20% fat, 20% carbohydrate, 5% fiber, and 10% minerals and vitamins. It is believed that Chlorella may offer many different health benefits. Chlorella contains large quantities of folate, vitamin B-12 and iron, and can help improve anemia and hypertensive disorder. A study of 70 pregnant women suggests that Chlorella supplementation significantly reduces the risk of pregnancy associated anemia, proteinuria and edema. Chlorella exhibits various anti-oxidative effects, Chlorella may have the benefits to prevent age-dependent cognitive impairment. Alzheimer's disease animal model was fed with chlorella and oxidative stress was reduced, the decline of cognitive ability was also declined. It has been thought that Chlorella might benefit people at risk of diabetes, as chlorella vulgaris was once reported to have hypoglycemic effects. In a study, chlorella ingestion tests on 17 subjects with high-risk factors for lifestyle-related diseases were conducted. Researchers found that chlorella intake resulted in noticeable reductions in body fat percentage, serum total cholesterol, and fasting blood glucose levels. Chlorella may also benefit people suffered hypertension, fibromyalgia syndrome, different kinds of cancers, constipation, diabetes, bad breath and colds.. but more studies are needed to support these health-benefit claims. Short term use of chlorella is probably safe to healthy adults at low dosages. The common side effects include diarrhea, nausea, gas, green discoloration of the stools, and stomach cramping. Further, the side effects may also include allergic reactions and skin sensitivity to the sun. Chlorella may interact immunosuppressants. ______________________________________________________________________________________________ Brown Seaweed (Brown alga) In 1960s, wakame, the brown seaweed, became popular in the United States, widely available in Asian-American grocery stores. Wakame fronds are green and have a subtly sweet flavour and slippery texture. The leaves are be cut into small pieces as they will expand during cooking. Wakame is distributed either dried or salted, and used in miso soup and other preparations such as tofu salad. Goma wakame, or seaweed salad, is a popular side dish at American sushi restaurants. Wakame is a rich source of eicosapentaenoic acid, an omega-3 fatty acid, wakame is also a good source of magnesium and zinc. Asian soups and salads, contains a compound called fucoxanthin that may promote weight loss. Fucoxanthin is found at high concentrations in several different types of brown seaweed. But it is absent in green and red seaweeds. Brown kelp is a key ingredient of Japanese miso soup. Fucus, called rockweed or bladderwrack, is a tough, leathery brown alga. Bladderwrack (Bladder Wrack, Fucus vesiculosus) is a rockweed or seaweed having forked, brownish-green branches with gas-filled bladders. Bladderwrack can be found on the coasts of the North Sea, the western Baltic Sea, the Atlantic and Pacific Oceans and it is also a common food in Japan. Bladderwrack extract containing fucoidan was found to promote fibroblast-populated collagen gel contraction by increasing the integrin alpha2beta1 expression on fibroblast surface.. A significant decrease in skin thickness and a significant improvement in elasticity were found when a Bladderwrack gel (1%) topically onto human cheek skin twice daily for five weeks. Thus, some people believe bladderwrack may have benefit of anti-aging effects. Fucoidan is a highly sulfated glycosaminoglycan from bladderwrack, which has a molecular structure similar to that of heparin. The antithrombotic effects of fucoidan in vitro have been widely reported. Bladderwrack fucoidan has an inhibitory effect on proinflammatory cytokine production and proliferation of vascular cells. Bladderwrack may have benefits of preventing thrombosis, but more studies are needed to clarify its effects. Bladderwrack may also have benefits on people suffered from cancer, diabetes and other diseases, again, more studies are needed to prove its health benefit-claims. Bladderwrack is possible safe for most healthy subjects at low doses, but high doses of bladderwrack may worsen or cause thyroid problems. Prolonged high doses of bladderwrack is linked with goiter or even increased risk of thyroid cancer. _____________________________________________________________________________________________ Red Seaweeds (Red algae) Porphyra and Chondrus are important in the diet - food in China and Japan. Commercial agar (vegetable gelatin) is obtained from species of red algae and widely used in food and pharmaceutical industries. Irish moss or carrageen (Chondrus crispus) has also been used in food preparation for a long time. Carrageenans are large, highly flexible molecules. They are pseudoplastic; they are less viscous under shear stress and recover their viscosity, once the shear stress is removed. This is similar to Ketchup. If you let it sit, it is thick. But if you shake the ketch up bottle, the ketch up becomes thin, and you can pour it out from the bottle easily. There are at least three types of carrageenans - kappa, lota and lambda. They all have different properties and uses. Carrageenan has been frequently used in animal studies to induce oedema.