Flaxseed, also known as linseed, has been talked about since the 1950s as a potential cancer-fighting food. The grain is available as flour, meal, and seeds. It's found in some multi-grain breads, cereals, breakfast bars, and muffins. The toasted seeds can be sprinkled into salads, yogurt, or smoothies.

Just like omega-3 fatty acids, flaxseed is a good source of lignans — compounds that may have a weak estrogen effect. When a weak estrogen-like substance takes the place of your body's natural strong estrogen in a breast cell's estrogen receptor, then the weak substance can act as a relative anti-estrogen. By acting in this way, lignans might help work against breast cancer that depends on estrogen for its growth. The lignans are concentrated in the hull of the flaxseed. If the seeds are ground up, your body has an easier time getting to the lignans.

Most of the evidence of the protective effects of flaxseed has come from a few small studies done in animals. Research on flaxseed in humans is needed to study its possible effects on cancer.

Flaxseed can help keep your cholesterol down and your bowel health up. The oil in flaxseed, alpha-linoleic acid, is an omega-3 essential fatty acid. And flaxseed is high in fiber. If you choose to eat it, start with a small amount and make sure you drink plenty of water. The U.S. Department of Agriculture makes no recommendation about the amount of flaxseed you should eat each day. But many dietitians advise eating 1 or 2 tablespoons of ground flaxseed meal daily.