Time for an Oil Change: The Health Benefits of Olive Oil

As a preventive health-care specialist, Dr. Edelson encourages patients to make nutrition a priority. But, keeping abreast of nutritional research can be a daunting challenge. That's why Dr. Edelson provides patients with research-based nutritional information that's easy to digest (no pun intended). By addressing one topic at a time with clear and concise explanations in "plain English," Dr. Edelson helps patients effortlessly grasp complex nutritional concepts and learn to comfortably make related dietary modifications. This week's topic: olive oil.

What makes olive oil so wholesome? Olive oil is a monounsaturated fatty acid (MUFA). Compared with the heart-clogging saturated fatty acids in butter and the polyunsaturated fatty acids (PUFAs) in vegetable oil, MUFAs ward off heart disease. In addition, olive oil contains oleic acid, which is perhaps the most healthful fatty acid for humans.

Be Heart Smart
People who consume a "Mediterranean diet" enjoy a reduced risk of heart attack and stroke. Researchers speculate that the abundance of olive oil in Mediterranean cuisine may partially account for this phenomenon. One study found that the blood of men who ate olive oil-based fare for three weeks was less likely to clot following a fatty meal, compared with the blood of men who consumed sunflower or canola oil-based diets. (Am J Clin Nutr 1999; 70:976-82)

Bypass Blood Pressure Drugs
Scientists in Italy have discovered that a diet rich in olive oil may allow those with high blood pressure to bypass medication. Researchers divided 23 patients with high blood pressure (hypertension) into two groups. One cohort followed a diet rich in extra-virgin olive oil. A second group ate a diet high in sunflower oil. After adhering to the diets for six months, subjects switched groups and followed the other diet for six months.

The blood pressure of participants in the olive oil group was significantly lower than the blood pressure of those who ate sunflower oil. What's more, the olive oil-based diet triggered a 48% drop in blood pressure medication use, compared with a 4% decline in drug use among subjects who consumed sunflower oil. And, eight patients in the olive oil group were able to discontinue medication altogether. On the other hand, all the patients in the sunflower oil group continued to require medication. (Arch Intern Med 2000; 160:837-42) Olive oil contains polyphenol chemicals, which are thought to bolster nitric oxide levels, support arterial health, and keep blood pressure under control.

Cut Down Cholesterol Levels
Populations that use olive oil as their primary fat source enjoy lower levels of total cholesterol and LDL ("bad") cholesterol. In addition, olive oil appears to inhibit the oxidation of LDL, a chemical reaction that sparks the formation of arterial plaque. (Free Radic Res 1999; 30:275-85)

Avert Arthritis
A recently published Greek study demonstrates that a diet rich in olive oil staves off rheumatoid arthritis (RA). Researchers pooled diet survey data on 188 control subjects without RA and 145 patients with RA. The analysis revealed that people who ate the least amount of olive oil were 2.5 times more likely to develop RA than were participants who ate the highest amounts of olive oil. (Am J Clin Nutr 1999; 70:1077-82)

Mend Your Mind
A diet rich in olive oil may prevent dementia, researchers report. One study looked at 378 seniors in southern Italy. Subjects underwent cognitive tests and completed questionnaires assessing their intake of various foods. The study found that a diet rich in MUFAs, which were primarily supplied by olive oil, prevented memory loss. This relationship was dose-dependent: the more MUFAs a subject consumed, the greater his or her protection from cognitive decline. (Neurology 1999; 52:1563-9)

What accounts for olive oil's brain, boosting qualities? Experts speculate that MUFAs maintain the integrity of brain cell membranes, which are composed of lipids.

Crush Cancer
A daily dose of olive oil may keep several types of cancer at bay. For example, a review study by investigators at the Harvard School of Public Health in Boston, Mass., concluded that a diet rich in olive oil may ward off breast cancer. (Am J Cliz Nutr 1997; 66:1557S-63S) Researchers also speculate that olive oil slashes the risk of pancreatic cancer. (Acad Sci 1999; 889:193-203)

Olive oil may also prevent colon cancer, according to ongoing research. In one recent experiment, scientists divided 100 rats into three diet groups: (1) safflower oil, (2) fish oil, or (3) olive oil. One-half of the animals in each group were then given a cancer-inducing agent.

Rats fed safflower oil developed more pre-cancerous tissue and tumors than rats fed either the fish or olive oil. Fish oil and olive oil also reduced the amount of arachidonate, a chemical involved in the synthesis of a known colon cancer-promoting agent called prostaglandin E (Gut 2000; 46:191-9).

Smooth Your Skin
Looking for an inexpensive yet extremely effective skin toner? Look no farther than your kitchen, say researchers. Olive oil is a potent moisturizer. And, this ancient health tonic is loaded with antioxidant chemicals, which may protect the skin from aging.

Studies show that olive oil inhibits damage to the skin's DNA, which may result in wrinkles and skin cancer. For example, in one study, scientists subjected mice to cancer-causing ultraviolet radiation. They found that painting super-virgin olive oil on the animals' skin following radiation sessions averted DNA mutation and "significantly delayed the onset and reduced the number of skin cancers." (J Dernlatol Sci 2000; 23: S45-50)

Choosing & Using Olive Oil
What should you consider when shopping for olive oil? First, choose an extra-virgin variety. Extra-virgin oil is made from the crop's first pressing and maintains acid levels below 1%. And, extra-virgin oil is tastier than virgin, pure, and light varieties. What's more, extra virgin is the most heart-healthy type of olive oil. It seems that extra-virgin oil contains more disease-fighting antioxidants than do more processed varieties. Studies show that, compared with refined olive oil, extra-virgin oil is more powerful at deterring the oxidation of LDL ("bad") cholesterol — an important step in the formation of arterial plaque. (J Nutr 1999; 129:2177-83)

Next, select a "cold pressed" oil. Oils manufactured without heat retain more nutrients than do those exposed to heat. Finally, look for oils made from organically grown olives. Pesticides used on olive crops may be carcinogenic.

Store olive oil in colored-glass containers in a dark cabinet. Do not shelve olive oil in open or warm areas, like above the stove. Sunlight and heat both trigger chemical reactions that spoil oil and produce disease-causing free radicals. If you live alone or don't cook often, buy small bottles to prevent spoiling. And, toss out any oil that smells rancid.

The key to maximizing the benefits of olive oil is substituting this health elixir for less nutritious lipids, rather than simply adding olive oil to your diet. (Overall, calories from fat — including olive oil — should account for no more than 30% of your daily total caloric intake.) When substituting olive oil for hard lipids, such as butter or lard, use one-third less olive oil than the amount of hard lipid called for by the recipe.