Diet Rich in Olive Oil, Nuts Beat Low-Fat Diet in 3-Month Study of High-Risk Adults
By Miranda Hitti
WebMD Medical News
Latest MedicineNet News
Reviewed By Louise Chang, MD
on Wednesday, July 05, 2006
July 5, 2006 -- Traditional Mediterranean diets that include nuts and olive oil may help protect the heart in those at high risk for heart disease.
That news comes from Spain's Ramon Estruch, MD, PhD, and colleagues. Estruch works in the internal medicine department at the University of Barcelona Hospital Clinic.
Estruch's team studied 772 adults at high risk for heart disease. Participants met at least one of two criteria:
- Type 2 diabetes
- 3 or more heart disease risk factors: smoking, high blood pressure, high levels of LDL ("bad") cholesterol, low levels of HDL ("good") cholesterol, family history of heart disease, and overweight BMI (body mass index).
Participants were 55 to 80 years old (average age: 68) and 90% were overweight or obese, based on BMI standards. None were known to have heart disease, severe chronic illness, or addiction to drugs or alcohol.
The researchers randomly assigned participants to spend three months on one of the following diets:
- Low-fat diet limiting all types of fats
- Mediterranean diet with free supplies of walnuts, almonds, and hazelnuts
- Mediterranean diet with free supplies of virgin olive oil
A dietitian taught each of the Mediterranean diet groups about their assigned diet and provided shopping lists and recipes. The researchers also supplied olive oil to one Mediterranean diet group and walnuts, hazelnuts, and almonds to the other Mediterranean diet group.
That was a pretty big head start, compared with the low-fat diet group. Those participants only got a low-fat diet brochure based on American Heart Association guidelines from 2000. They didn't get any classes, shopping lists, or recipes.
It's often tough to get people to comply with diet studies, the researchers note. Here's what happened in their study:
- Those in the low-fat group trimmed only a little fat from their diets.
- All 3 groups started eating more vegetables, legumes, fruit, and fish. They also cut back on meat, sweets, and dairy products.
- All 3 groups cut back on saturated fat (olive oil contains unsaturated fat).
- The 2 Mediterranean diet groups cut their cholesterol consumption.
- The nut eaters added more fiber and ate fewer carbohydrates.
- Weight held steady in all 3 groups.
Compared with the low-fat group, the two Mediterranean diet groups had bigger improvements in blood pressure, insulin resistance (a problem which accompanies or precedes type 2 diabetes), markers of inflammation, and levels of cholesterol and other lipids (blood fats).
The researchers acknowledge the low-fat group may have been at a disadvantage, since they didn't get as much training at the study's start.
One researcher notes financial ties to the California Walnut Commission.
The olive oil and nuts were supplied by Spanish and Californian companies.
Olive Oil Primer
Curious about which olive oil might be best for your health -- plain olive oil, virgin olive oil, or extra virgin?
WebMD's director of nutrition Kathleen Zelman, MPH, RD, explains the terms.
"The only difference among olive oils is the degree of purification or refinement," Zelman notes. "The more virgin, the purer the oil -- but in terms of healthy fats, it makes no difference."
The word "light" appears on some olive oil labels. "Light" refers to the oil's color and fragrance, not fat, calories, or flavor, states the American Dietetic Association's web site.
SOURCES: Estruch, R. Annals of Internal Medicine, July 4, 2006; vol 145. Kathleen Zelman, MPH, RD, director of nutrition, WebMD. American Dietetic Association: "Does Extra Virgin Olive Oil have Fewer Calories?"
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