High in natural chemicals that lower cholesterol and fight disease, avocado oil is increasingly touted at least by growers and processors as even more healthful than current favorites olive and canola.
Most health claims about the oil are drawn from studies about the fruit itself (yes, avocado is a fruit), rich in a plant compound called beta-sitosterol, which helps block absorption of cholesterol in the intestines.
Like the fruit, the oil has antioxidants such as vitamin E, believed to reduce coronary artery disease and help the skin; lutein, a carotenoid that protects the eyes against diseases like cataracts and macular degeneration and that may guard against prostate cancer; and glutathione, which regulates other antioxidants, such as vitamins C and E.
But while acknowledging the benefits of oils, such as avocado, that are high in monounsaturated fats, nutritionists question whether these other nutritional components will make much difference in your daily diet.
"The beta-sitosterol does help block cholesterol absorption, but there are better forms of it. For instance, Benecol margarine, which can actually claim that," said Dr. Sheldon Margen, a professor of public health at the University of California, Berkeley. That's because Benecol contains a converted version of beta-sitosterol, called a stanol, that's better at blocking cholesterol.
"The thing about oil is, you're not supposed to use very much of it. I don't care how many nutrients it has in it," said Dale Ogar, managing editor of the UC Berkeley Wellness Letter.
Regardless of the type of fat it contains, she said, "it's still nine calories per gram, just like any other fat."
Most of the buzz about avocado oil, pressed from the green flesh of the fruit, is coming from New Zealand, where manufacturers are now producing not only the oil, also avocado oil spreads and avocado oil capsules as a source of vitamin E.
In California, where 90 percent of U.S. avocados are grown, gourmet companies are selling the oil at specialty food and health stores, alongside such heart-healthful oils as olive, canola, safflower, and sunflower, all rich in the good fats known to lower bad cholesterol.
Avocado oil like olive oil, canola oil, and peanut oil is high in desirable monounsaturated fats, while safflower, sunflower, corn, flaxseed, and canola oils are rich in polyunsaturated fats, which also lower bad cholesterol.
Fats occur in several forms. Saturated fats, like those found in butter and red meat, were considered the least healthful for the heart and blood vessels until health officials began focusing on trans fats found in solid shortenings and partly hydrogenated vegetable oils.
Nutritionists advise sticking with monounsaturated oils, which can lower bad cholesterol, and polyunsaturated oils, which not only lower cholesterol, but also provide some of the fatty acids, like linoleic acid and alpha-linoleic acid, that the body needs to function.
Avocado oil can be an expensive choice in a field crowded with alternatives to solid shortenings and saturated fats.
"Most consumers who walk into an oil section [of a supermarket] get overwhelmed when they walk past sunflower, safflower, and canola," said Leslie Brenner Newman, spokeswoman for Spectrum Organic Products Inc. in Petaluma, Calif., which sells a refined avocado oil for cooking, skin care, and massage.
"Unless there is an informed employee who can explain how this oil would work, they will go to the olive and canola, the stand-bys."
Avocado oil is available in the so-called "virgin" varieties, which have a greenish color and stronger taste, and refined versions, which have a more golden hue and milder taste. Because it has a high smoking point, meaning it won't burn or smoke until it's heated to nearly 500 degrees compared with 374 for olive oil the oil is suitable for searing meat and stir-frying meats, fish, and vegetables.
However, high heat breaks down many of the antioxidants that make it attractive, so some manufacturers emphasize its appeal in salad dressings and for dipping bread, much like the olive oil found on restaurant tables.
Dr. David Heber, director of the UCLA Center for Human Nutrition and an adviser to the California Avocado Commission, said that from the consumer's standpoint, "it's still the same oil as olive oil, largely monounsaturated. Theoretically, it's healthy, and some studies show a modest lowering of cholesterol, comparable to if you're using olive oil."
But, he said, "there are no magic fats. Remember: 120 calories a tablespoon."
How a tablespoon of avocado oil stacks up against two other popular oils touted as healthful:
Olive oil: Calories: 120. Total fat: 14 grams. Saturated: 2 grams. Monounsaturated: 10 grams. Polyunsaturated: 1 gram.
Canola oil: Calories: 120. Total fat: 14 grams. Saturated: 1 gram. Monounsaturated: 9 grams. Polyunsaturated: 4 grams.
Avocado oil: Calories: 120. Total fat: 14 grams. Saturated: 2 grams. Monounsaturated: 10 grams. Polyunsaturated: 2 grams
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