Olives come from olive trees, providing both the fruit itself and oil from the fruit. They are a savory food--preserved in water, brine, oil or marinades--and are eaten in salads, sandwiches, meat dishes, in tapenades and spreads, and as an appetizer or garnish. Olives are very nutritious and can contribute to a healthy diet.
Olives are one of the oldest cultivated foods known, originating in the Mediterranean area thousands of years ago and have been a staple food of many civilizations, including Greece, Egypt and Rome. They were brought to America in the 18th century by Franciscan missionaries. Now, olives are grown predominantly in Turkey, Greece, Spain and Italy. In the United States, olives are grown in California.
A 28-gram serving of pickled green olives contains about 41 calories, with 36 calories coming from fat. The serving has 4 g of fat, 1 g of carbohydrates, no protein and 1 g of dietary fiber. The same size serving of black olives has 23 calories with 16 calories coming from fat. The serving has 2 g of fat, 2 g of carbohydrates, no protein and 1 g of dietary fiber. Olives are rich in monounsaturated fats and also contribute Vitamin E and various polyphenols and flavonoids.
The antioxidant and anti-inflammatory effects of vitamin E and monounsaturated fats in olives, along with the available polyphenols and flavonoids, help protect the body against free radicals. These are chemicals that damage cells and can contribute to diseases, including certain cancers and heart disease. Olives can also help reduce the effects of arthritis, asthma and other inflammatory diseases and disorders. Monounsaturated fats also help to reduce cholesterol.
Olives can't be eaten fresh from the tree. They must be prepared first to reduce the levels of oleoropein, a chemical in olives that causes bitterness. Some olives are picked green, while others are allowed to turn black and fully ripen before being prepared. The olives may change color, depending on the preservation method used. This does not affect the nutritional value of the olives.
Olives tend to be high in sodium due to the salt used in the preservation process. People with high blood pressure, kidney problems, congestive heart failure and other diseases that are affected by sodium intake may want to limit the amount of olives eaten.