Spirulina may be small in size, but its advocates claim it's a nutritional powerhouse. As one of the many "hot" products in the vast and complex world of nutritional supplements, its usage has exploded exponentially in recent years and has created a hype that may or may not be supported by conclusive scientific evidence. What is spirulina, and what are its benefits? Let's investigate.

Spirulina, one of many blue-green algae, is a microorganism that grows on the surface of lakes in warmer climates, such as Latin America and Africa. It has been harvested, dried, and eaten by the people of these regions for centuries. Believed to be highly nutritious, spirulina is often made into cakes and broths and was a staple of the Aztec diet. Today, spirulina is approved by the World Health Organization as a health food.

A nutritional analysis of spirulina showed that it is 55% to 77% protein by dry weight, and as such, is considered a complete protein superior to all other plant proteins, including legumes. It contains all the essential amino acids and a study from Kansas State University in 2005 confirms that it is a source of five essential amino acids, which the human body cannot make. It is rich in potassium and also contains calcium, chromium, copper, iron, magnesium, phosphorus, selenium, sodium, and zinc. It contains vitamin B1 (thiamine), B2 (riboflavin), B3 (nicotinamide), B6 (pyridoxine), B9 (folic acid), and B12 (cyanocobalamin); however, the actual amount of available B12 is in dispute - in fact, the Dietitians of Canada do not recognize spirulina as a reliable source of active vitamin B12. Additionally, spirulina is rich in essential fatty acids and contains vitamin C, vitamin D, and vitamin E.

Even though it is approved as a health food, using spirulina as an effective therapeutic agent is widely disputed. In spite of existing supportive research, critics remain skeptical and often contend that evidence pointing to spirulina as a therapeutic agent is overstated by its advocates. Countering these arguments, advocates insist that the studies that exist do show promise and health claims should not be dismissed without acknowledging this research.

Animal research has provided the strongest evidence of the health benefits associated with spirulina. Researches at the University of South Florida have found that rats that were given diets supplemented with spirulina following induced strokes showed brains lesions 75% smaller than those of control group rats. The same team has also found that the brains of aged rats that were fed spirulina supplements (which have high antioxidant activity) maintained their neuron function much better than those rats fed with cucumbers (which have less antioxidant activity). The spirulina-fed rats also showed far less free-radical damage. Free-radical damage is associated with aging and diseases like Alzheimer's and cancer. Whether these free-radical-reducing results seen in rats are present in humans is yet to be seen.

Given its high antioxidant content, spirulina has often been praised as an immune system booster. In fact, human studies have shown that spirulina is effective in fighting allergies and may help fight HIV. A study from UC Davis showed that human white blood cells were able to launch a stronger immune response in the presence of spirulina, and allergy sufferers who take 2 g of spirulina daily experience a significant reduction in their symptoms. Preliminary results of studies from the Dana-Farber Cancer Institute and Harvard Medical School showed that spirulina extract holds some promise in fighting HIV and other viruses. Further groundwork research has shown spirulina extract to be able to inhibit HIV replication. While these preliminary results are promising, more research is needed in order to show that spirulina actually helps fight HIV infection.

More recently, a 2007 clinical trial suggests spirulina supplementation might help lower cholesterol and reduce hypertension. Participants who were given 4.5 g of spirulina for 6 weeks showed lowered total cholesterol, increased good cholesterol, and lowered triglycerides. Results from this study also showed spirulina to lower both systolic and diastolic blood pressure of the participants.

Spirulina is widely available as a dietary supplement in pill or powder form. As there are no known toxicities associated with spirulina, it is safe to consume with the standard dosage being set at 2 g to 3 g per day. As with any natural health product, the therapeutic claims associated with spirulina are continuously researched and, at present, no health claim is made by Health Canada.

While it may be enjoyed as a welcomed addition to the diet, any health benefits attributed to spirulina beyond its dietary function remain tentative. Further research, particularly human studies, are needed to fully qualify spirulina as an effective preventative treatment against specific diseases.

Brennan Robertson, Hon. B.Sc. (Nutrition)