Pond Scum Makes a Health Splash

From the WebMD Archives

Dec. 11, 2000 -- The lowly single-celled Spirulina -- a form of blue-green algae that thrives in brackish pond water -- has hit the big time. Not only has the World Health Organization endorsed it as a vitamin- and protein-rich food supplement for undernourished people, a group of California researchers has recently suggested the organism may help protect against infectious diseases, and even cancer.


Predictably, however, experts advise you don't dash down to the pond just yet. Not enough studies have been done to determine the safety of using Spirulina pills or powders, they point out, and although the plant's vitamins and minerals may indeed have health benefits, you would have to eat an awful lot of algae to see any of them.


Still, scientists are considerably interested in the ancient plant. In the current issue of The Journal of Medicinal Foods, M. Eric Gershwin, MD, an allergy and immunology specialist at the University of California, Davis, describes a lab experiment in which he and colleagues added Spirulina algae to human immune system blood cells and then documented an increase in the production of proteins, called cytokines, that fight infection.


"Spirulina stimulates cytokines that we use to fight colds," Gershwin tells WebMD. "This is basically the equivalent of eating a concentration of very nutritious vegetables."


In their paper, Gershwin and colleagues refer to previous studies praising the potential health benefits of Spirulina. One study showed that it works as a natural antihistamine in rats, helping to ease their allergies. Another showed that in chickens it increases the activity of cells that kill infected and cancerous cells.


"I'm not recommending that people go out every day and eat Spirulina, but this is a supplement that has potential to help the immune system," Gershwin says.


One worrisome aspect of Spirulina is that it is also high in beta-carotene, which a number of vitamin studies have concluded has no particular health benefit when taken as a supplement and may even cause a higher risk of lung cancer, especially in smokers. (Gershwin points out that the participants in those studies were taking very high doses of beta-carotene.)


In any case, experts agree that Spirulina is not a cure-all.


According to Mayo Clinic doctors, while Spirulina's protein, beta-carotene, and vitamin B-12 could certainly help people who are malnourished, it's doubtful they would do much to keep already well-nourished people healthy. The vitamin B-12 in Spirulina is not as easily absorbed by the body as it is from animal products, they say. In addition, Spirulina is an expensive source of protein -- about $70 a month.


"Whether these plants have bona fide benefits over a long period of time -- who knows?" says David Karp, MD, PhD, assistant professor of immunology at the University of Texas Southwestern Medical Center at Dallas. "All things that come from plants have some effect, but they would have to be studied for a long period to find out if [they're] significant."


Lona Sandon, a registered dietitian and clinical nutrition instructor at UT Southwestern, tells WebMD people should approach all hyped supplements with a skeptical eye.


"Spirulina is touted as a cure for just about anything; any time a product claims to do that much, people should question it," she says, adding that it would take 20 500-mg pills made of the algae, every day, to get the benefits manufacturers claim the plant can provide. "A banana, an orange, and a piece of whole wheat bread is much more satisfying," she says.


One more thing to consider, she says: "The product is not regulated by the FDA, and it grows on top of the water. This means it has a high potential for contamination from bacteria." Because of this, she says, Spirulina users can be at serious risk of food-borne illnesses, including gastrointestinal diseases that lead to vomiting, nausea, and diarrhea.


Even more dangerous is the high vitamin K content of Spirulina -- which can interfere with some medications, like Coumadin, a blood thinner prescribed to those who may be subject to stroke-causing blood clots. "The Spirulina may lower your cholesterol but it will inhibit your blood-thinning medications, putting you at greater risk for stroke," Sandon says.


Also at danger, she says, are those whose immune system is compromised due to AIDS or because they underwent chemotherapy or radiation treatment for cancer. Any supplement that contains bugs and bacteria could be deadly for these patients.