It’s true what they say about Mediterranean diet

You won't find an inch to pinch on Jessica Knurick. At 6-foot-1, the UNLV assistant professor and researcher weighs in at a lean-and-mean 150 pounds. Her total cholesterol hovers around 110, which is crazy low — in a good way.

To stay in fighting trim, Knurick, 26, follows the Mediterranean diet, which she took up six years ago as a south Florida college student with bad eating habits and chronic low energy.

"I decided to make a conscious change and eat more fruits and vegetables and whole grains," said Knurick, an avid marathoner. "When I did that, my energy level just skyrocketed. I had more mental clarity and I just started feeling better."

Knurick's healthful choices may pay off in a much bigger way down the road, as she ages.

The Mediterranean diet is associated with a reduced risk of death from heart disease and cancer, and a lower incidence of Parkinson's and Alzheimer's diseases. It may also help with mental acuity as we age.

"The cardiovascular disease benefits are the ones that have been most clearly delineated over time," said Miriam Een, assistant professor of nutrition at the University of Nevada School of Medicine.

But Een pointed to studies suggesting the diet may battle many other conditions — from rheumatoid arthritis to inflammatory bowel disease and depression.

There is no single definition of a Mediterranean diet. In general, it emphasizes foods often relegated to cameo rather than starring roles in our eating lives: fruits and vegetables, whole grains, legumes and nuts; fish and poultry (at least twice a week); and splashes of olive oil.

The diet limits red meat to a few times a month and favors herbs and spices over salt. Red wine in moderation is OK. Physical activity is important, too.

How exactly does this diet do good things for us? The key may be olive oil.

Olive oil is an unsaturated fat that lowers LDL, the "bad" cholesterol that can build up inside our arteries and cause blockages that lead to heart attacks and strokes, said Alice H. Lichtenstein, a researcher in nutrition and heart disease at Tufts University.

The diet eschews butter, which is a saturated fat that raises bad cholesterol levels. Also absent from the Mediterranean diet are trans fats, which come from partially hydrogenated vegetable oils and are strongly related to risk of heart disease.

Mary Flynn, a research dietitian at Brown University, is so convinced of the health benefits of olive oil that she calls this golden-hued liquid "more medicine than food."

"People with diets including daily consumption of extra virgin olive oil have lower rates of most chronic diseases, such as heart disease, cancers, arthritis, and Type 2 diabetes," Flynn said.

But not all olive oils are equal.

Extra virgin olive oil — EVoo — is the way to go, and the fresher the better, Flynn said. Fresh extra virgin olive oil is higher in a family of chemicals called phenols, which the dietitian credited with doing good things such as lowering blood pressure and decreasing blood clotting.

Two tablespoons of extra virgin olive oil a day can produce salutary effects "and many studies show that the benefits increase with higher intakes," Flynn added.

But make sure that the extra virgin olive oil you drop into your supermarket cart is of good quality. Studies at the University of California, Davis, found many substandard extra virgin olive oils on store shelves, even among top-selling brands.

But the Mediterranean diet's effectiveness isn't all about olive oil, according to Harvard researcher Walter Willett.

Willet is a big proponent of the Mediterranean diet. He noted that epidemiologic evidence supports the role of fruits and vegetables, whole grains, fish and even moderate consumption of alcohol, in the diet's effectiveness.

In fact, Willett wrote in the journal Public Health Nutrition, that more than 80 percent of coronary artery disease, 70 percent of stroke, and 90 percent of Type 2 diabetes can be avoided "with healthy food choices that are consistent with the traditional Mediterranean diet."

Last month, the diet got a big nod from the U.S. government with the release of the 2015-2020 Dietary Guidelines. This latest edition of the guidelines points to a "Healthy Mediterranean-Style Eating Pattern" as one of two diets that promote good health. The other is the "Healthy Vegetarian Eating Pattern."

Damon McCune, a dietitian and director of the Didactic Program in Nutrition and Dietetics at UNLV, likes a lot of elements of the Mediterranean diet.

Some of McCune's patients experience lower blood pressure and lower total cholesterol when they follow the diet. Some also see reductions in LDL cholesterol or triglycerides, a type of fat found in blood, he added.

But McCune finds some aspects of the Mediterranean diet troubling, particularly its emphasis on foods with high fat content, such as olive oil and nuts.

"Even if you are eating healthy things, you can still over-consume and gain weight," he said. "A tablespoon of olive oil is 100 calories, so you can very quickly eat a lot of calories with the fat that you are consuming."

McCune also thinks the diet paints red meat with too broad and negative a brush. "A lot of the time, the research doesn't specify the kind of red meat or the fat content. A top sirloin or any other lean cut of beef will be very different than, say, deli meat," he said.

As long as you're choosing a lean cut, there's no reason to fear red meat, which is rich in nutrients and a good source of protein, especially for people who don't like fish, McCune said.

Examples of lean cuts are eye of round and flank steak, he added. More examples can be found at the website beef.org, McCune added.

The UNLV Nutrition Center offers free counseling and workshops on healthy eating. For information, visit https://www.unlv.edu/kns/nutrition-center.