Alpha-linolenic acid is an essential omega-3 fatty acid. It is called "essential" because it is needed for normal human growth and development. Nuts, such as walnuts, are good sources of alpha-linolenic acid. It is also found in vegetable oils such as flaxseed (linseed) oil, canola (rapeseed) oil, and soybean oil, as well as in red meat and dairy products. Alpha-linolenic acid is popular for preventing and treating diseases of the heart and blood vessels. It is used to prevent heart attacks, lower high blood pressure, lower cholesterol, and reverse "hardening of the blood vessels" (atherosclerosis). There is some evidence that alpha-linolenic acid from dietary sources might be effective for all these uses except lowering cholesterol. Not enough is known yet to be able to rate alpha-linolenic acid's effect on high cholesterol.