Algae refers to a variety of plantlike organisms that live in water, including the blue-green algae spirulina, seaweeds like kelp and wakame, and brown algae like laminaria, or kombu. These sea vegetables provide some essential nutrients and may have some health benefits, but there are also some potential risks, especially if you consume them in large amounts.
Different types of algae offer slightly different nutritional value. Dried algae is a more concentrated source of nutrients, as raw algae is about 80 percent water, compared to less than 5 percent water in dried algae. Algae can be high in copper, iron, thiamine, riboflavin, manganese, vitamin K and protein. Algae may even help fight malnutrition, according to a July 2010 article on the United Nations Food and Agriculture Organization website. The algae spirulina provides the beta carotene, iron and protein that are often lacking in some people's diets.
Potential Health Benefits
A substance called fucoxanthin, found in some types of brown algae, may help lower your risk for cancer and obesity and can also act as an anti-inflammatory and an antioxidant, according to a review article published in the International Journal of Molecular Sciences in July 2013. It may also have a protective effect on your neurons and your brain, notes another review article published in Advances in Food and Nutrition Research in 2011.
Blue-green algae also acts as an antioxidant, and some types may help lower cholesterol, reduce inflammation and help prevent certain diseases, including heart disease and nonalcoholic fatty liver disease, according to an article published in Journal of Medicinal Food in February 2013. This research is still preliminary, however, and further studies are necessary to verify any potential benefits of algae.
Potential Side Effects
Some people may be allergic to algae and experience the symptoms of an allergic reaction, such as rash, difficulty breathing, swelling and anaphylaxis. Other potential side effects include goiter, skin reactions and gastrointestinal effects. Some types of dried seaweed are high in iodine, which could cause an increase in the amount of thyroid-stimulating hormone in your body and give your skin a yellow tint or cause a skin outbreak that looks like acne if you consume them in large amounts. Pregnant women should avoid the brown algae laminaria, as it may dilate the cervix, resulting in preterm labor.
Other Considerations and Risks
Some types of algae can be high in sodium, so people with high blood pressure or heart disease should check with their doctor before consuming algae. People with phenylketonuria or an autoimmune disease shouldn't take spirulina, as it may make these conditions worse. It may also interact with medications that suppress immune function and blood thinners.
Only take algae supplements that have been certified free of contamination. Products contaminated with a substance called microcystin could cause liver, kidney and brain damage, and those contaminated with cyanotoxin could also cause seizures, pancreas, heart or respiratory problems.
Contaminated products may cause thirst, vomiting, nausea and stomach pain. Some types of algae are toxic and could cause numbness, weakness, diarrhea, nausea, tingling and death.