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Are Vitamin A & Spirulina Dangerous?

By Teresa Bergen

Ever since spirulina became a popular health supplement in the late 1960s, proponents have touted it as superfood rich in vitamin A, protein and other nutrients. While people around the world grow and eat spirulina, most of them safely, there are a few possible risks.

Vitamin A and Beta-carotene

Getting sufficient vitamin A is essential for bone growth, vision and protecting your immune system. Vitamin A is partially responsible for growing healthy linings in your eyes and in your digestive, urinary and respiratory tracts. There are two basic kinds: retinol, which is found in animal sources, and carotenoids, found in plants, which your body converts to retinol. Beta-carotene is the easier carotenoid for the body to convert. The RDA for vitamin A is 700 micrograms for women and 900 for men. When you eat foods with beta-carotene, your body only converts as much to vitamin A as you need. There’s no RDA for beta-carotene, and it’s considered safe even in large amounts, except for smokers.


Spirulina is a type of blue-green algae grown on lakes and farms all over the world. Eating algae goes back at least to the Aztecs, who dried it into blue-green cakes. Spirulina contains a high concentration of protein, and is a good source of vitamin A and iron. The supplement is also used for weight loss, hayfever, PMS, diabetes and many other conditions, most of which lack solid scientific support. It can be eaten dried or raw, but contains more nutrients in dried form.

Vitamin A in Spirulina

Dried spirulina is unusual in that it contains both vitamin A and beta-carotene. A half cup contains 171 micrograms of vitamin A and 342 micrograms of beta carotene. Together this adds up to more than half the day’s vitamin A RDA for men and women. Raw spirulina is much less nutritious, containing only about 16 micrograms of vitamin A.


While spirulina is a good source of vitamin A, it’s extremely unlikely you’d eat enough to overdose. The tolerable upper limit is 3,000 micrograms, which means you would have to eat close to 20 cups of dried algae, which even the most ardent spirulina lovers would find a formidable challenge. If you did this daily over time, you might face a cumulative vitamin A overdose leading to osteoporosis, birth defects and liver damage. What’s much more likely is that you could have a condition that doesn’t mix well with spirulina, or that you’d get a contaminated batch. If you have phenylketonuria or any type of auto-immune disease, don’t take spirulina. If you are pregnant or on medications, be sure to talk to your doctor before adding supplements to your diet. Only buy blue-green algae that’s been tested for for mycrocystins and other contaminants. Contaminated algae can lead to nausea, cramping, liver damage and even death.

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