Arguably the “superfood” of the moment, spirulina is associated with a number of health claims, from curing allergies and candida to detoxifying the body and aiding in weight loss. Does this blue-green algae deliver, or is it all health hype?
As it turns out, these claims are backed by little science and likely surfaced due to spirulina’s impressive nutrient profile. One ounce, or approximately 4 tablespoons, of dried spirulina contains 81 calories, 16 grams of protein, 60 percent of the daily value of riboflavin, 44 percent of the daily value of iron and thiamin, 14 percent of the daily value of magnesium and 11 percent of the daily value of potassium.
The Natural Medicines Comprehensive Database lists all health claims associated with spirulina as having insufficient evidence to rate, and warns that women who are pregnant or breast-feeding should avoid it. There also is some evidence that spirulina could interact with anticoagulant, antiplatelet and immunosuppressant drugs. Due to its high protein content, people with phenylketonuria, or PKU, should not consume spirulina.
After the Natural Medicines monograph was updated in 2015, a double-blind, placebo-controlled, randomized trial of 40 individuals with hypertension was published in 2016. It found that consuming 2 grams of spirulina for three months led to improved BMI, body weight and blood pressure in this small sample. While spirulina is very protein-dense and these results seem promising, there is not enough information at this time to recommend it as a supplement for specific health conditions.
Due to its growing popularity, spirulina is cultivated in ponds and mass-produced all over the world, including Hawaii and China. Spirulina’s distinctive and strong seaweed flavor leads many people to consume it via capsule, while others mix the powder form into water, juice or smoothies. Contamination by toxins and heavy metals is a serious concern, so it is important to choose a spirulina supplement with reliable third-party testing and quality assurance.
Taylor Wolfram, MS, RDN, LDN, is an associate editor of Food & Nutrition and a dietetics content manager at the Academy of Nutrition and Dietetics.