Green peas provide protein and carbohydrates, B vitamins, iron, potassium, vitamin A, folate and calcium. Leeks, which come from the same family as onions and garlic, contain little-known cardiovascular benefits: They contain polyphenols, antioxidants that protect blood vessels and cells from oxidative damage, and kaempferol, a flavonoid that reportedly protects blood vessel linings from damage. This soup is great served hot or cold.