of Mexi-co and Central America, is popular with nutritionists and the
health-conscious everywhere. Often labelled 'the world's healthiest food',
it's been said to boost immunity, promote heart health, combat fatigue,
encourage weight loss, eliminate allergies and even protect against cancer.
Is there any truth to these claims? WDDTY separates the fact from the
- Nasal allergies. In a controlled clinical trial, allergic rhinitis
patients fed spirulina had signifi-cantly less sneezing, itching, nasal
discharge and congestion, compar-ed with the placebo group (Eur Arch
Otorhinolaryngol, 2008; 265: 1219-23).
- High cholesterol. When the effects of spirulina on cholesterol were
studied over 20 years ago in 30 healthy men, it was found that
4.2 g/day markedly reduced levels of LDL ('bad') cholesterol
after eight weeks (Nutr Rep Int, 1988; 37: 1329-37). Other clinical trials
have reported similar results and, in one, spirulina not only reduced LDL
cholesterol, but also increased HDL ('good') cholesterol, too (Evid Based
Comple-ment Altern Med, 2008 Sep 14; Epub ahead of print).
- Hypertension. In 36 Mexican men and women, taking 4.5 g/day of
spirulina for six weeks dramatically reduced both systolic and diastolic
blood pressure, with the largest decreases seen in the youngest (aged 18-38
years) (Lipids Health Dis, 2007; 6: 33).
- Arsenic poisoning. This is a common problem in developing countries
where arsenic levels in drinking water are high. When 41 patients with this
condition were given either a placebo or spirulina extract (250 g) plus zinc
(2 g), twice daily for 16 weeks, urine and hair analyses found that the
spirulina- zinc combo removed significant quantities of arsenic from the
body (Clin Toxicol [Phila], 2006; 44: 135-41).
- Obesity. In the only trial of spirulina for weight loss, there was a
small reduction in weight in obese people taking 2.8 g of spirulina three
times a day. However, further studies are needed to confirm this, and it is
also not known whether the supplement will have the same effects in those
who aren't so overweight (Nutr Rep Int, 1986; 33: 565-74).
- Cancer. In one clinical trial, researchers found that 20 out of 44
patients showed complete regress-ion of leukoplakia (mouth cancer) after
taking spirulina for one year vs only 3 out of 43 taking a placebo (Nutr
Cancer, 1995; 24: 197-202). However, this was an "unblinded, non-randomized
trial and as such cannot be regarded as evidence of a positive effect" (Evid
Based Complement Altern Med, 2008 Sep 14; Epub ahead of print).
Other studies show that spirulina doesn't work for certain conditions.
Although it's often claimed to fight fatigue and boost energy, a random-ized
placebo-controlled trial suggests otherwise. When four patients with chronic
fatigue were given spirulina
(3 g/day) for a month, it proved no better than a placebo (Phytother Res,
2007; 21: 570-3). However, as these results may have been biased by the
design of the study, until more clinical studies are conducted, we just
Another claim is that spirulina can protect the liver, especially in people
with chronic hepatitis. However, a trial of 24 patients with chronic viral
hepatitis found that one month of spirulina treatment had no significant
results (Rom J Intern Med, 2002; 40: 89-94).
It's also worth noting that, despite the widespread publicity, there's no
evidence that spirulina can help in attention-deficit disorder.
The bottom line
Although the spirulina studies are promising, it's still too early to say
whether or not it can prevent or treat any specific health problem. What's
more, the dosages used in most of the studies were relatively high, so even
it does work, you'd need to take a lot of it to see any benefits. Still, as
dietary supplements go, spirulina is a particularly rich source of proteins,
vitamins, amino acids, minerals and other nutrients. This means that,
providing you choose a good-quality supplement, you can't go far wrong.
Is spirulina safe?
Spirulina itself appears to be non-toxic, although blue-green algae may be
naturally contaminated by highly toxic substances called 'microcystins',
which could make their way into health supplements. Nevertheless, a survey
by Health Canada-which tested a broad sample of blue-green algae products
available on the Canadian market-found that all spirulina products were
microcystin-free (for details, go to
A genuine concern, however, is that spirulina can absorb any heavy metals
present in the water in which it grows (Nutr Rep Int, 1989; 40: 1165-72), so
make sure that you buy spirulina from a reputable manufacturer.
Vol. 20 08 November 2009