Flaxseed is the small, flat seed of the flax plant, valued for thousands of years both as food and as the source of linen fiber. These oval seeds, about the size of sesame seeds, come in golden or brown varieties and have a mild, nutty flavor.

People eat flaxseeds for their nutritional benefits, especially their omega-3 fatty acids, which support heart and brain health. You might find them sprinkled on yogurt, baked into bread, or ground into a powder called flaxseed meal. Whole flaxseeds can pass through your digestive system undigested, so grinding them helps your body absorb their nutrients.

The flax plant has an impressive history. Ancient Egyptians used flax to make linen cloth for clothing and mummy wrappings, while people across many cultures ate the seeds for nourishment. Even today, linen fabric comes from the same plant that produces flaxseeds.

When mixed with water, ground flaxseed forms a gel-like substance that some bakers use as an egg substitute in recipes. The seeds also produce linseed oil (another name for flaxseed oil), used for everything from wood finishing to oil painting.