Flaxseed

Flaxseed is a whole seed rich in fiber, plant omega-3 (ALA), and lignans. Authoritative nutrition sources list flax as a top ALA source; a tablespoon of whole seeds provides roughly 2.35 g ALA, while flaxseed oil is higher per spoon but lacks fiber and lignans. Human studies and a Health Canada review support modest LDL-cholesterol reductions when ground flaxseed is eaten daily at about 40 g, with smaller amounts contributing to fiber intake and regularity. Lignans in flax act as antioxidants and may help lipid and inflammation profiles, though findings are less consistent. Overall, evidence supports flaxseed for improving a few cardiometabolic markers as part of a balanced diet. Safety concerns focus mainly on cyanogenic glycosides that can release hydrogen cyanide when raw ground flax is eaten. EFSA set an acute reference dose for cyanide at 20 μg/kg body weight, and the EU limits hydrocyanic acid levels in linseed; heat and moisture during processing lower cyanide potential. Small adult servings (for example 1–2 tablespoons) are unlikely to pose risk, and a small human study summarized in a narrative review reported no adverse effects after about 30 g of ground flax with only transient low plasma cyanide. The most common side effects are digestive—gas, bloating, or loose stools—especially if intake jumps quickly or fluids are low. Major health agencies advise that pregnant or breastfeeding people and those on certain medications consult a clinician before using flaxseed or its oil.