Is Spirulina Safe While Pregnant?

Spirulina is a blue-green algae that is sold as a supplement purported to have numerous health effects from boosting immune function to lowering cholesterol to helping prevent cancer. It is also sold as a general health booster that is high in protein, iron and other minerals. However, if you are pregnant, your doctor may advise you to avoid this supplement.

A spoonful of spirulina powder next to some spirulina pills. Credit: thelefty/iStock/Getty Images


There is not enough scientific information about consuming spirulina during pregnancy to make a determination on whether using it while pregnant or breast-feeding is safe. This means that the safe choice is to avoid this supplement while pregnant or nursing.

Heavy Metals

Spirulina has the potential to be contaminated with mercury and other heavy metals. Mercury can affect the nervous system as well as brain development. Possible mercury contamination is the reason behind recommendations to limit other food from the sea, such as fish, if you are pregnant. U.S. Food and Drug Administration guidelines call for consuming no more than 12 oz. of low-mercury fish like snapper, flounder or cod each week.

Other Contamination

Spirulina might also be contaminated with microcystins, which are liver-damaging substances, as well as harmful bacteria. Babies and children are more sensitive to contaminated spirulina than adults. Contaminated spirulina can cause vomiting, liver damage, rapid heartbeat, thirst, shock and even death. Whether pregnant or not, avoid any spirulina product that is not tested and certified free of contaminants, including mycrocystins.


You do not know whether your unborn child has phenylketonuria, or PKU, a rare condition in which your baby lacks the ability to properly break down phenylalanine, an amino acid. This causes phenylalanine levels to build up in the body, which can cause brain damage and be harmful to the central nervous system. Spirulina contains phenylalanine. Most states require that newborns be tested for PKU.

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