Before the time of coral or starfish or bugs or birds, blue-green alga was practically the only living thing on earth. More than 1,500 species of the primitive single-celled organism are still around, mostly floating in stagnant ponds and growing on algae farms.

That's right: algae farms. This ancient plantlike creature has become a cash crop. Web sites and health food stores tout blue-green algae (also called spirulina) as a most potent superfood and claim that it can boost energy, aid weight loss, help cleanse the body's tissues, and even alleviate diseases ranging from diabetes and Alzheimer's to attention deficit disorder, gynecological disorders, and precancerous lesions of the mucus membranes.

Undoubtedly. Whether you call it a superfood or pond scum, algae is packed with beta-carotene and protein. (It contains vitamin B-12, too, but in a form that the body can't absorb). The supplements also include large amounts of heart-healthy polyunsaturated fatty acids. In addition, at least one species of algae contains alpha-linoleic acid, a compound that might help prevent heart disease and some types of cancer.

Indeed, the algae is still a major source of nourishment in some areas of the world. The World Health Organization uses blue-green algae supplements to boost the health of malnourished children in India.

It may be full of salubrious goodies, but at $50 to $70 for a month's supply, it isn't necessarily a smart buy. The foul-tasting supplements are meant to be taken in small doses -- too small to be a significant source of protein or beta-carotene. Unless you're malnourished, your body will barely notice these extra nutrients. If you want more of them, foods such as tofu and nuts (for protein) and green bell peppers and oranges (for beta-carotene) may be more economical and tastier choices.

Furthermore, if you're counting on algae to give you some gamma-linoleic acid to ward off heart disease and cancers, caveat emptor! Many species do not contain this compound, and supplement makers don't have to identify the species on their product labels.

Almost all of the health claims used to market blue-green algae are unfounded. There's no proof that the supplements boost energy or alleviate diabetes, attention deficit disorder, Alzheimer's, or any other disease. However, one recent study at Harvard Medical School did find that supplements of Aphanizomenon flos-aquae, a species of blue-green algae that contains gamma-linoleic acid, lowered the cholesterol levels of lab rats. Although nobody has tried such a study with humans, it's possible that A. flos-aquae supplements could benefit people with high cholesterol.

The typical dose of blue-green algae is 3 to 5 grams daily before meals.

It's possible that blue-green algae can be contaminated with mercury, arsenic, or microbes from animal waste such as sea gull guano. In addition, many species of blue-green algae produce toxins called microcystins. In nature, the poisons can be strong enough to kill a cow that drinks from the wrong pond. These toxins occasionally show up in supplements, setting off diarrhea, nausea, weakness, numbness, or tingling. (If a salesperson tells you that such symptoms show that your body is being cleansed, don't believe it.)

A researcher at the University of Alberta tested the microcystin levels in nine different algae supplements, and every sample had more of the poison than the World Heath Organization deems safe. (Spirulina, a common form of blue-green algae, has not been shown to contain toxins at harmful levels, according to Health Canada.)

Mycrocystins may even be able to cause liver damage, particularly in children. For this reason, the Canadian Health Protection Branch has urged parents not to give blue-green algae to their children for attention deficit disorder or for any other reason.

If you have a metabolic disorder known as phenylketonuria, you should also avoid blue-green algae. At least in theory, taking it could exacerbate your condition, according to the Natural Medicines Comprehensive Database.

-- Chris Woolston, M.S., is a health and medical writer with a master's degree in biology. He is a contributing editor at Consumer Health Interactive, and was the staff writer at Hippocrates, a magazine for physicians. He has also covered science issues for Time Inc. Health, WebMD, and the Chronicle of Higher Education.

References

First published January 26, 2000
Last updated January 31, 2008
Copyright © 2000 Consumer Health Interactive

Back to top of page