What might make nuts heart healthy?

Nuts are a good source of protein. Most nuts also 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. Many nuts are rich in omega-3 fatty acids. Omega-3s are healthy fatty acids. They may reduce the risk of heart attacks and strokes.
• Fiber. All nuts contain fiber, which helps lower cholesterol. Fiber also makes you feel full, so you eat less.
• Plant sterols. Some nuts contain plant sterols, a substance that can help lower 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. Some research suggests that L-arginine may lower blood pressure, improve cholesterol and improve overall blood vessel health.