Energy value (calories per serving): Moderate
Saturated fat: High Cholesterol: None Carbohydrates: Moderate Fiber: High to very high Sodium: Low
Major vitamin contribution: Vitamins A, folate, vitamin C
Major mineral contribution: Potassium
About the Nutrients in This Food
The avocado is an unusual fruit because about 16 percent of its total weight is fat, primarily monounsaturated fatty acids. Like many other fruits, avo- cados are high in fiber (the Florida avocado is very high in fiber), a good source of the B vitamin folate, vitamin C, and potassium.
The edible part of half of one average size avocado (100 g/3.5 ounces) provides 6.7 g dietary fiber, 15 g fat (2.1 g saturated fat, 9.7 g monoun- saturated fat, 1.8 g polyunsaturated fat), 81 mcg folate (20 percent of the R DA), 20 mg vitamin C (26 percent of the R DA for a woman, 22 percent for a man), and 485 mg potassium (the equivalent of one eight-ounce cup of fresh orange juice).
The edible part of one-half a Florida avocado (a.k.a. alligator pear) has eight grams dietary fiber, 13.5 g fat (2.65 g saturated fat), 81 mcg folate (41 percent of the R DA for a man, 45 percent of the R DA for a woman), 12 mg vitamin C (20 percent of the R DA), and 741 mg potassium, 50 percent more than one cup fresh orange juice.
Diets That May Exclude or Restrict This Food
Controlled-potassium diet Low-fat diet
Buying This Food
Look for: Fruit that feels heavy for its size. The avocados most commonly sold in the U.S. are the Hass—a purple-black bumpy fruit that accounts for 85 percent of the avocados shipped from California—and the smooth-skinned Florida avocado (“alligator pear”). The California Avocado Commission lists several more on its Web site (http://www.avocado. org/about/varieties): the oval, midwinter Bacon; the pear-shaped, late-fall Fuerte; the Gwen, a slightly larger Hass; Pinkerton, pear-shaped with a smaller seed; the round summer Reed; and the yellow-green, pear-shaped Zutano.
Avoid: Avocados with soft dark spots on the skin that indicate damage underneath.
Storing This Food
Store hard, unripened avocados in a warm place; a bowl on top of the refrigerator will do. Avocados are shipped before they ripen, when the flesh is hard enough to resist bruising in transit, but they ripen off the tree and will soften nicely at home.
Store soft, ripe avocados in the refrigerator to slow the natural enzyme action that turns their flesh brown as they mature even when the fruit has not been cut.
Preparing This Food
When you peel or slice an avocado, you tear its cell walls, releasing polyphenoloxidase, an enzyme that converts phenols in the avocado to brownish compounds that darken the avocado’s naturally pale green flesh. You can slow this reaction (but not stop it completely) by brushing the exposed surface of the avocado with an acid (lemon juice or vinegar). To store a cut avocado, brush it with lemon juice or vinegar, wrap it tightly in plastic, and keep it in the refrigerator—where it will eventually turn brown. Or you can store the avocado as guacamole; mixing it with lemon juice, tomatoes, onions, and mayonnaise (all of which are acidic) is an efficient way to protect the color of the fruit.
Medical Uses and/or Benefits
Lower risk of some birth defects. As many as two of every 1,000 babies born in the United States each year may have cleft palate or a neural tube (spinal cord) defect due to their moth- ers’ not having gotten adequate amounts of folate during pregnancy. The current R DA for folate is 180 mcg for a healthy woman and 200 mcg for a healthy man, but the FDA now recommends 400 mcg for a woman who is or may become pregnant. Taking folate supple- ments before becoming pregnant and through the first two months of pregnancy reduces the risk of cleft palate; taking folate through the entire pregnancy reduces the risk of neural tube defects.
Lower risk of heart attack. In the spring of 1998, an analysis of data from the records for more than 80,000 women enrolled in the long-running Nurses’ Health Study at Harvard School of Public Health/Brigham and Woman’s Hospital, in Boston, demonstrated that a diet providing more than 400 mcg folate and 3 mg vitamin B6 daily, from either food or supplements, more than twice the current R DA for each, may reduce a woman’s risk of heart attack by almost 50 percent. Although men were not included in the analysis, the results are assumed to apply to them as well.
However, data from a meta-analysis published in the Journal of the American Medical Association in December 2006 called this theory into question. Researchers at Tulane Univer- sity examined the results of 12 controlled studies in which 16,958 patients with preexisting cardiovascular disease were given either folic acid supplements or placebos (“look-alike” pills with no folic acid) for at least six months. The scientists, who found no reduction in the risk of further heart disease or overall death rates among those taking folic acid, concluded that further studies will be required to ascertain whether taking folic acid supplements reduces the risk of cardiovascular disease.
Lower levels of cholesterol. Avocados are rich in oleic acid, a monounsaturated fat believed to reduce cholesterol levels.
Potassium benefits. Because potassium is excreted in urine, potassium-rich foods are often recommended for people taking diuretics. In addition, a diet rich in potassium (from food) is associated with a lower risk of stroke. A 1998 Harvard School of Public Health analysis of data from the long-running Health Professionals Study shows 38 percent fewer strokes among men who ate nine servings of high potassium foods a day vs. those who ate less than four servings. Among men with high blood pressure, taking a daily 1,000 mg potas- sium supplement—about the amount of potassium in one avocado—reduced the incidence of stroke by 60 percent.
Adverse Effects Associated with This Food
Latex–fruit syndrome. Latex is a milky fluid obtained from the rubber tree and used to make medical and surgical products such as condoms and protective latex gloves, as well as rubber bands, balloons, and toys; elastic used in clothing; pacifiers and baby-bottle nipples; chewing gum; and various adhesives. Some of the proteins in latex are allergenic, known
to cause reactions ranging from mild to potentially life-threatening. Some of the pro- teins found naturally in latex also occur naturally in foods from plants such as avocados, bananas, chestnuts, kiwi fruit, tomatoes, and food and diet sodas sweetened with aspar- tame. Persons sensitive to these foods are likely to be sensitive to latex as well. NOT E : The National Institute of Health Sciences, in Japan, also lists the following foods as suspect: A lmonds, apples, apricots, bamboo shoots, bell peppers, buckwheat, cantaloupe, carrots, celer y, cherries, chestnuts, coconut, figs, grapefruit, lettuce, loquat, mangoes, mushrooms, mustard, nectarines, oranges, passion fruit, papaya, peaches, peanuts, peppermint, pine- apples, potatoes, soybeans, strawberries, walnuts, and watermelon.
MAO inhibitors. Monoamine oxidase (M AO) inhibitors are drugs used as antidepressants or antihypertensives. They inhibit the action of enzymes that break down the amino acid tyramine so it can be eliminated from the body. Tyramine is a pressor amine, a chemical that constricts blood vessels and raises blood pressure. If you eat a food such as avocado that contains tyramine while you are taking an M AO inhibitor you cannot eliminate the pressor amine, and the result may be abnormally high blood pressure or a hypertensive crisis (sus- tained elevated blood pressure).
False-positive test for tumors. Carcinoid tumors (which may arise from tissues in the endo- crine system, the intestines, or the lungs) secrete serotonin, a natural chemical that makes blood vessels expand or contract. Because serotonin is excreted in urine, these tumors are diagnosed by measuring the levels of serotonin by-products in the urine. Avocados contain large amounts of serotonin; eating them in the three days before a test for an endocrine tumor might produce a false-positive result, suggesting that you have the tumor when in fact you don’t. (Other foods high in serotonin are bananas, eggplant, pineapples, plums, tomatoes, and walnuts.)