Have You Had Your Pond Scum Today?

In recent years various “green drinks” have become popular. They contain natural products—for example, wheat grass, barley grass, chlorella and spirulina. Of those, the one with the most potential for delivering a good supply of nutrients is spirulina.

You may already know that spirulina is a blue-green algae often seen floating on the top of lakes, where it’s referred to by the rather unsavory appellation of “pond scum.” In fact, there are 35 species of spirulina, with two of them commonly used in food products. While products containing spirulina may be trendy these days, it’s been around for a while. Spanish explorers in the New World found the Aztecs harvesting a “blue mud” that was likely spirulina. It was also harvested in the Sahara, where it was called dihe. In the United States, it became popular in food supplements around 1979.

You can still find protein supplements that feature spirulina as the primary ingredient. That no doubt reflects the fact that it contains 65 percent protein, including all 22 amino acids. On the other hand, its amino acid balance isn’t as ideal as that found in animal proteins like milk and eggs.

Spirulina also contains a good supply of B-complex vitamins, as well as beta-carotene and a wide spectrum of various trace minerals. Its iron content is unusual for a plant product in that it is easily absorbed by the body—not true of most plant-derived iron. Spirulina contains a form of fat called gamma-linoleic acid that is a direct precursor of beneficial chemicals produced in the body called prostaglandins. The specific nutritional breakdown of spirulina is as follows: 63.3 percent protein, 7.1 percent fat, 15.2 percent carbohydrate.

Spirulina offers various health benefits, including increased immune response due to particular sugars found in it. Research shows that it may help lower elevated cholesterol, probably because of its rich gamma-linoleic acid content, and it has antioxidant attributes as well. While many grasses bring on allergic reactions, spirulina blocks them at the source.

With all the benefits spirulina has to offer, its reputation as an energy food should come as no surprise. My sister-in-law, a physician, says that she always starts her day with a green drink and a handful of spirulina pills, which she says energizes and wakes her up better than coffee. Could it be that spirulina is also useful for athletic purposes or simply to aid those involved in intense weight training?

According to animal and test-tube studies, spirulina does boost energy and performance, likely because of its rich content of nutrients and antioxidants, but human studies are lacking. A recently published study sought to fill the gap in the medical literature. The subjects were nine moderately trained men, average age 23, most of whom were recreational runners. The study had a double-blind, placebo-controlled, crossover design, which meant that half the subjects received the active substance first, while the other half got a placebo. Then the groups reversed. In this case the active ingredient was spirulina, at a daily dose of six grams, taken after exercise and before meals three times a day. The placebo was 100 percent egg protein in capsules. The study lasted a month.

After four weeks those taking spirulina showed a longer time to fatigue following a two-hour run compared to those getting the placebo. The spirulina decreased carbohydrate use as fuel by 10.3 percent while increasing fat burning by 10.9 percent compared to the placebo. Total fat oxidation increased by 15.8 percent in the spirulina group. Basically, the spirulina shifted the energy use during the run from carbohydrate to fat.

While an extended run always produces a shift from carb to fat, that the effect was stronger in the spirulina group speaks for itself. Using spirulina amplified the effect, and it also increased a major body antioxidant called glutathione. The glutathione blunted fatigue by helping control the free radicals produced by the exercise.

As to why spirulina increased fat burning, the authors couldn’t supply an answer. They suspect, however, that the high content of gamma-linoleic acid in spirulina may be the reason. Previous studies have shown that GLA helps reduce bodyfat in rats and stimulates various enzymes involved in fat burning. One intriguing human study published a few years ago found that GLA appeared to block the rapid fat gains that occur after a diet ends. As for the upgraded antioxidant effect, the researchers point to the spirulina content of amino acids that act as precursors of glutathione, such as cysteine and methionine.

None of the subjects in the study experienced any side effects. On the other hand, use of the supplement is contraindicated in people who may be allergic to spirulina supplements. If you choose to use a product based on spirulina or one in which it’s a major ingredient, such as one of the green drinks, make sure that the spirulina is certified free of contaminants. That’s important because spirulina is often directly harvested from lakes and can accumulate toxic heavy metals from the environment, including mercury.

Kalafati, M., et al. (2010). Ergogenic and antioxidant effects of spirulina supplementation in humans. Med Sci Sports Exerc. 42:142-51.