Flaxseed is one of the best plant-based sources of omega-3 fatty acids. But:

Are Cyanide Levels in Flaxseed Safe?, Tuft’s University, August 2011

Q: I recently read that flaxseed contains cyanide. I have been consuming two to three tablespoons of ground flaxseed daily for several years. Should I be concerned? Does this quantity of flaxseed provide a clinically significant amount of cyanide?

A: Lynne M. Ausman, DSc, RD, director of the Biochemical and Molecular Nutrition Program at Tufts’ HNRCA Cardiovascular Nutrition Laboratory, says you have nothing to worry about. Many foods, including not only flax but cashews, almonds, some beans and other plant products, naturally contain very small amounts of cyanide compounds. You’re more likely to ingest these trace amounts of cyanide when such foods are consumed raw, as heat breaks down the compounds. Even when flaxseed is eaten raw, the body has a natural capacity to break down a certain amount of these cyanide compounds. A 1994 study found that, in healthy individuals, daily consumption of as much as 60 grams of raw flaxseed — more than eight tablespoons — was safe.