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Spirulina: Buy or Bye?

Taking a deep dive into trending foods and drinks to find out if they are worth the hype.


Manufacturers and social media proponents claim that spirulina, a type of single-celled microbe that grows in both fresh and saltwater—and is often referred to as blue-green algae—packs a punch of protein, antioxidants and other compounds that strengthen human health.

But quality spirulina research is scant. Some preliminary data suggests that supplementing with spirulina (3–6 grams daily) can help improve cholesterol and blood triglyceride numbers, allow for better blood sugar control in those with diabetes, help lower the risk for cancer, and maybe even make it easier to achieve weight loss goals. The green powder has also been shown to help in certain athletic pursuits such as allowing for higher peak and average power outputs during repeated sprinting tests.

We need a lot more research conducted on humans, however, to be able to form firmer conclusions regarding these health and performance outcomes. Yes, spirulina is relatively high in protein, at least by weight (about 70% of its mass is protein), but a one-teaspoon serving of spirulina powder has a mere 2 g of protein. You’d need to eat a ton of the stuff for it to noticeably contribute to your daily protein needs. Claims that the chlorophyll in spirulina helps detox the body and boost the immune system are not scientifically validated, to say the least.

Yet, one benefit of spirulina that’s legit is its sky-high levels of beta-carotene: A single teaspoon serving ponies up well over twice the daily requirement for this antioxidant that can be converted to vitamin A in the body. It’s also a decent source of vitamin K to help with blood clotting and bone health, but it’s no better than leafy greens like spinach and kale. Though spirulina is sometimes lauded as a vegan-friendly source of vitamin B12, it contains a form of pseudo B12 that is not bioavailable to the human body.

The verdict: While the algae does contain antioxidants and other nutritional virtues, there is not enough research to say that it will make a big impact on your diet and health. Especially if you already eat plenty of less-costly whole vegetables like dark leafy greens. Of concern, since spirulina grows in water, there is the risk it can become contaminated with heavy metals and other hazards. Some brands are third-party tested to show they are free of contamination and that you are getting what the label says.

See also: Micro Food for Mega Nutrition

Matthew Kadey, MS, RD

Matthew Kadey, MS, RD, is a James Beard Award–winning food journalist, dietitian and author of the cookbook Rocket Fuel: Power-Packed Food for Sport + Adventure (VeloPress 2016). He has written for dozens of magazines, including Runner’s World, Men’s Health, Shape, Men’s Fitness and Muscle and Fitness.

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