Flaxseed oil is derived from the hard, tiny seeds of the flax plant. It has been proposed as a less smelly alternative to fish oil. Like fish oil, flaxseed oil contains omega-3 fatty acids, a type of fat your body needs as much as it needs vitamins.

However, it's important to realize that the omega-3 fatty acids in flaxseed oil aren't identical to what you get from fish oil. Flaxseed oil contains alpha-linolenic acid (ALA), while fish oil contains eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The effects and potential benefits may not be the same.

Whole flaxseeds contain another important group of chemicals known as lignans.Lignans are being studied for use in preventing cancer. However, flaxseed oilcontains no lignans.1

Flaxseed oil contains both omega-3 and omega-6 fatty acids, which are essential to health. Although the exact daily requirement of these essential fatty acids is not known, deficiencies are believed to be fairly common.2 Flaxseed oil may be an economical way to ensure that you get enough essential fatty acids in your diet.

The essential fatty acids in flax can be damaged by exposure to heat, light, and oxygen (essentially, they become rancid). For this reason, you shouldn't cook with flaxseed oil. A good product should be sold in an opaque container, and the manufacturing process should keep the temperature under 100 degrees Fahrenheit. Some manufacturers combine the product with vitamin E because it helps prevent rancidity.