Found in warm waters around the world, spirulina is a blue-green algae that’s become a popular ingredient in
smoothies and protein powders . One of its many appealing features is that, in its natural form, spirulina absorbs nutrients from its environments, which food and supplement companies have marketed as a rich source for various vitamins and nutrients. But what else do we know about spirulina benefits?
Spirulina is labeled a superfood, and holistic health experts and TikTok influencers swear it as a game-changer for your health. But nutritionists warn there is. “If people choose to consume supplements or foods containing it, they should be aware of the scientific strength of the health claims on the product and that there is often a need for further research,” explains Emma Laing, Ph.D., R.D.N., the director of dietetics at the University of Georgia and a national spokesperson for the Academy of Nutrition and Dietetics.
Lon Ben-Asher, M.S., R.D., L.D.N., a nutritionist at Pritikin Longevity Center advises against people using the algae, citing the lack of safety data around it and evidence that it actually works. “We should be more focused on leading a healthy lifestyle to prevent and reduce the risk of chronic diseases. Incorporating more vegetables, fruits, potatoes, beans/lentils/legumes, whole grains and unrefined carbohydrates, and some fish should be the cornerstone to helping facilitate that.”
Spirulina is nutritious and experts say it has the potentialto keep your body health. It holds a high nutrient-dense profile containing protein and essential amino acids including:
Dr. Laing says its diverse nutrient portfolio has made it the subject for a number of research studies looking into the algae’s health benefits. For example, the antioxidant and anti-inflammatory properties found in the superfood are thought to minimize the cell and tissue damage caused by a high fat diet and protect heart health. Spirulina has also been associated with regulating blood sugar levels, managing allergies, promoting weight loss, and a lower risk of some cancer types.
What’s more, the supplement could serve as an extra protein option for vegetarians or vegans looking to diversify their palate. Although you won’t want to completely rely on it as your only source of protein. Dr. Laing says you would need to eat a large amount of spirulina each day to meet your daily protein requirements. Instead, “nuts, legumes, dairy, meat, fish, poultry, and eggs provide rich sources of protein in far smaller servings.”
However, both experts stress that research is still ongoing and caution against making medical recommendations with the limited evidence available–for example, most research has been tested in the lab or on animals. Studies on humans have been mainly observational, drawing inferences and correlations based on associations they detected in people using spirulina. In spite of a lack of clinical evidence, Dr. Ben-Asher says companies continue to make unproven claims on its ability to treat a variety of conditions from macular degeneration, dental infections, to multiple mental health conditions.
It is considered safe to consume. Like any supplement, you run the risk of minor but not life-threatening side effects such as:
Dr. Ben-Asher also points out there are rare cases of allergic reactions that range from mild to anaphylactic shock.
The more pressing concern is the high potential of contamination in the lake where spirulina is sourced from. Dr. Laing explains that the water where the blue-green algae grows in can absorb heavy metals—lead, arsenic, cadmium, or mercury—and harmful bacteria from its immediate environment. There have also been reports of spirulina products containing microcystins, a type of toxin that can cause severe damage to the liver depending on the amount ingested.
If you want your supplement to stay contaminant-free, do your research. Dr. Laing says you should look for companies that grow spirulina in a controlled laboratory environment and have proof the company tests products for contaminants.
“There’s no guarantee that even the most rigorously tested products are 100% safe,” she explains. “People wishing to purchase the product should do so from a reputable company that tests its products for contaminants.” Consumers will be far less likely to be exposed to harmful substances.
The best way to extend the shelf-life of spirulina is keeping it in a cool area that’s dry with little moisture or the fridge. Because it is available in multiple forms—from a powder to sprinkle on your oatmeal to pill supplements—there is no hard-fast expiration date. However, Dr. Laing say that the nutritional quality will degrade over time and to consume the product a few months after opening it.
Both experts suggest looking for a tag with a ‘Use By,’ ‘Best if used by,’ or ‘Guaranteed-fresh-until’ date. If a product passes its freshness date, it does not necessarily mean it’s no longer safe to eat, says Dr. Laing. The dates are more of a signpost of when you would get the best nutritional value and peak quality of the product. “Even if a "Best By" date has passed on a product you have at home, it should be safe to consume if stored and handled properly,” she explains.
Dietary supplements are not regulated by the Food and Drug Administration. People with certain conditions may be at risk for harmful side effects or experience negative interactions with other medications they are currently taking. Both experts recommend people with the following conditions nottake spirulina:
Because of the lack of data on how this so-called superfood affects kids and the risk of potential metal contamination, young children, people who are pregnant, and people are breastfeeding are also advised to avoid it. Dr. Laing adds that people taking blood thinning medications or those about to or who just had surgery should not use the supplement either.
As always, talk to your health care provider before taking a new supplement—and whether you need to consume the algae in the first place.
Dietary supplements are products intended to supplement the diet. They are not medicines and are not intended to treat, diagnose, mitigate, prevent, or cure diseases. Be cautious about taking dietary supplements if you are pregnant or nursing. Also, be careful about giving supplements to a child, unless recommended by their healthcare provider.