What might make nuts heart healthy?

Besides being packed with protein, most nuts contain at least some of these heart-healthy substances:

• Unsaturated fats. It's not entirely clear why, but it's thought that the "good" fats in nuts — both monounsaturated and polyunsaturated fats — lower bad cholesterol levels.
• Omega-3 fatty acids. It's well known that omega-3 fatty acids are found in fish, but many nuts also are rich in omega-3 fatty acids. Omega-3s are healthy fatty acids that seem to help your heart by, among other things, preventing irregular heart rhythms that can lead to heart attacks.
• Fiber. All nuts contain fiber, which helps lower your cholesterol. Fiber also makes you feel full, so you eat less. In addition, fiber is thought to play a role in preventing type 2 diabetes.
• Vitamin E. Vitamin E may help stop the development of plaques in your arteries, which can narrow them. Plaque development in your arteries can lead to chest pain, coronary artery disease or a heart attack.
• Plant sterols. Some nuts contain plant sterols, a substance that can help lower your cholesterol. Plant sterols are often added to products such as margarine and orange juice for additional health benefits, but sterols occur naturally in nuts.
• L-arginine. Nuts are also a source of L-arginine, which is a substance that may help improve the health of your artery walls by making them more flexible and less prone to blood clots that can block blood flow.