Many people avoid avocados, thinking they’re too fattening and that they raise blood cholesterol. First, let’s clear up these confusions, so that everyone can enjoy these full-bodied, velvety fruits (yes, they are fruits, not vegetables) without guilt.
Though avocados are high in calories for a fruit (110 to 180 per half, depending on the variety), that doesn’t mean you’ll necessarily gain weight if you eat them. And though it’s true that avocados have a lot of fat (10 to 15 grams per half), the fat—like that in olive and canola oils—is predominantly monounsaturated fat, which doesn’t raise blood cholesterol. In fact, avocados may actually help reduce cholesterol, according to a 2015 study in the Journal of the American Heart Association, which generated a lot of media buzz.
Avocados: what the research shows
The study, funded by the Hass Avocado Board, included overweight or obese adults who followed three different low-saturated-fat diets designed to lower cholesterol. One diet was low-fat and high-carb (24 percent of calories from fat). One was moderate in total fat (34 percent of calories) but high in monounsaturated fat, largely from vegetable oils. The third was similar in composition to the second diet except its monounsaturated fat came largely from a daily avocado.
After five weeks, all three diets reduced cholesterol, but the avocado one lowered it most. Moreover, only the avocado diet reduced small, dense LDL cholesterol particles (considered more harmful than large, “fluffy” particles). The researchers said the benefits may be due to the combined effects of the fat, fiber, and compounds called phytosterols in avocados.
This wasn’t the first study to show potential cardiovascular benefits of avocados. According to a paper in Critical Reviews in Food Science and Nutrition, research dating back more than 50 years found that avocados had either a cholesterol-lowering or cholesterol-neutral effect. Then, several studies in the 1990s found that they lowered LDL (“bad”) cholesterol in particular, compared to high-carb, low-fat diets. And an analysis of national nutrition data collected from 2001 to 2008 noted that people who ate avocados tended to have higher HDL (“good”) cholesterol and lower risk of metabolic syndrome.
Other studies over the last few years—several of which were funded by the Hass Avocado Board—have yielded additional encouraging findings about avocados. Keep in mind that other foods and oils with similar nutrient profiles would likely havesimilar effects.
- They may counter the effects of “bad” fats. In a pilot study from UCLA in the journal Food & Function, researchers measured blood vessel contractibility and inflammatory markers in 11 people after they ate hamburgers with and without avocado. Blood vessel constriction occurred two hours after eating the plain burger but not after the avocado-adorned burger. The avocado also lessened the effect the burger had on an inflammatory marker. Meals high in saturated fats (as from meat) can impair endothelial functioning, increase inflammation, and lead to blood vessel constriction, thus increasing the risk of angina or heart attack. The polyphenols and unsaturated fats in avocados may help counter this by altering inflammatory pathways, the researchers proposed.
- They may help in weight control. In a small study in the Nutrition Journal, overweight or obese people who ate half an avocado at lunch reported increased satisfaction and decreased desire to eat for several hours afterwards, compared to when they ate a control (no avocado) lunch. Having some avocado with a meal may thus help prevent excessive snacking between meals, the researchers concluded. Using data from a national food survey, another study in the Nutrition Journal noted that avocado eaters tend to weigh less and have smaller waist circumferences than avocado abstainers (they also tend to have better diets in general—higher in vegetables, fruits, and fiber and lower in sugar). Some researchers think that a unique sugar in avocados, Dmannoheptulose, may help with blood sugar control and weight management.
- They boost absorption of carotenoids from low-fat or nonfat foods. In a study in the Journal of Nutrition, eating avocado with tomato sauce or raw carrots increased absorption of beta carotene (which is fat-soluble) from these foods.
Avocados: fun facts
Avocados were cultivated in Mexico as early as 2,500 years ago and introduced to the U.S. in the 19th century. California is the leading avocado producer in the nation (though continuing drought conditions there may affect production and price since avocados are a water-intensive crop). The name comes from the Aztec word ahuacatl, meaning testicle, perhaps because of the shape of avocados and the way they hang from trees in pairs. The Spanish conquistadors pronounced the word as aguacate, the forerunner of the English word “avocado.” The Aztecs believed that avocados had aphrodisiac properties, though there are no studies to confirm that they have any direct effects on sexual desire or performance.
There are hundreds of varieties, with different sizes, shapes, textures, colors, and flavors. They even vary in the size and shape of their pits, how easily they peel, and what they look like when ripe (some stay green, some get darker, some turn dull). Only a few varieties are generally available in the? U.S., however, with Hass (the smaller, purple-black, pebbly-skinned kind) predominating. Florida avocados? (the larger, lighter-green, smoother-skinned kind with more watery and fibrous flesh) have less fat and fewer calories per ounce.
In addition to healthful unsaturated fats, phytosterols, and fiber—5 to 8 grams per half, the most of all fruits—avocados are good sources of potassium, magnesium, folate (and other B vitamins), vitamin K, and copper. Plus they’re rich in antioxidants, including vitamins C and E, carotenoids (like lutein and zeaxanthin), and polyphenols (which may also have anti-inflammatory properties and beneficial effects on blood vessels). The darker green flesh just below the peel contains the most carotenoids. ?Just be wary of the unsubstantiated or exaggerated health claims made for avocados on the Internet—for example, that they can prevent prostate cancer and kidney stones, heal ulcers, and boost immunity.
See also our recipe for Crab and Avocado Salad.
Published July 14, 2015