You've probably heard of the Mediterranean diet. It's touted everywhere from morning news shows to magazine articles as one of the most healthful eating styles around, but you may not know how or why this diet — which is filled with fruits and vegetables from places like Italy, Greece and Turkey — is so good for you.
Science is only just beginning to decipher why eating some foods, skipping others or combining them in the right ways can thwart illness and ward off disease.
What does the Mediterranean diet look like?
"The Mediterranean diet includes foods and beverages native to the land for which it's named. Rich in fruits, veggies, whole grains, nuts, beans, legumes, a variety of herbs and spices, wine, fish, seafood and olive oil, this meal plan may reduce the risk of heart disease and other inflammatory conditions like arthritis," says Martina Cartwright, a registered dietitian.
The foundation of the diet consists of fruits like apricots, citrus, dates, figs, grapes, apples and pears; veggies like tomatoes, avocados, kale and dark green leafy spinach, onions, garlic and leeks, celery, carrots, cabbage and cucumbers; beans and legumes like chickpeas (hummus), fava beans and kidney beans; nuts like cashews and almonds; red wine (a glass a day); fish three times a week and a serving or two of low-fat dairy or yogurt each day (think Greek yogurt). Olive oil is recommended for cooking and is the main source of dietary fat in salad dressings and baking along with fats from avocado and nuts.
Why is this food regimen so healthful?
"The Mediterranean diet has been shown to significantly reduce risk for cardiovascular disease and for recurrence of cardiac events. It also reduces risk for type 2 diabetes, metabolic syndrome and Alzheimer's disease, and is associated with fewer cardiovascular- and cancer- related deaths, decreased risk of stroke and depression, improved physical functioning, and a slower rate of cognitive decline," says Julieanna Hever, author of "The Complete Idiot's Guide to Plant-Based Nutrition."
"The mechanism for how the diet works is unclear. However, the theory is that since the diet is rich in anti-inflammatory fats (olive and fish) and antioxidants (which help with cell repair and include vitamin C, vitamin E, beta carotene and phytochemicals), it helps the body’s repair mechanisms," Cartwright says.
A 2016 study presented at the European Society of Cardiology Congress backs up the heart health benefits, even among those who are already showing signs of cardiovascular disease.
Using 25,000 random adults from the Italian region of Molise, researchers found 1,197 with histories of heart disease. Those participants who adhered closely to the diet saw their death rate from any cause drop by 37 percent over the study's seven year period. The researchers acknowledged that their study was "observational" and that further research was needed to establish a causal link.
The Molise researchers may need only to look at a 2014 study that may have unearthed a "secret ingredient" that gives the Mediterranean diet such a powerful effect on health and longevity. When the unsaturated fat in olive oil meets the naturally occurring nitrates that many Mediterranean vegetables (such as tomatoes, eggplant, garlic and leafy greens) are rich in, a special kind of molecule is produced called nitro fatty acids.
Lowering heart disease risk may not be the only thing the diet's good for, either. A 2017 study published in the journal Neurology shows that the Mediterranean diet also helps with brain health.
Researchers followed the eating habits of 967 Scots around the age of 70 who showed no signs of dementia for three years. MRIs were conducted on 562 to measure brain volume at the start of the study, with 401 of them receiving another brain scan at the end of the study. Scans were compared to how closely the participants followed the diet, and researchers found that those who didn't stick to the diet showed a higher loss of total brain volume over three years than those who did. The results remained the same when researchers accounted for other facts such as education, age and blood pressure.
"In our study, eating habits were measured before brain volume was, which suggests that the diet may be able to provide long-term protection to the brain," said study author Michelle Luciano. "Still, larger studies are needed to confirm these results."
How do nitro fatty acids work?
Researchers from King's College London and the University of California, Davis used genetically engineered mice to figure out how this biochemical process worked.
Beneficial omega-6 fats are normally broken down in the body by an enzyme, but these nitro fatty acids block the action of that enzyme. As a result, the "good fats" stay in the blood longer, where they may have a long-lasting effect.
"The Mediterranean diet may reduce inflammation and blood pressure through a unique combination of dietary fats and nitrogen-rich vegetables. When consumed together in a meal, this dynamic duo form a type of fat that may help reduce blood pressure, bad cholesterol and perhaps inflammation," Cartwright says.
The theory is, the longer the good fats stick around, the more opportunity they have to elicit healthful benefits in the body.
Hever says she believes the benefits of the diet stem from the fact that it is plant-heavy, providing opportunities for synergy to occur, as mentioned in the research. "Synergy between phytochemicals and other nutrients in plant foods work harmoniously to enhance immune function and protect against chronic degenerative diseases," she says.
In fact, she believes there are likely thousands of similar reactions that are the result of consuming a wide variety of plant foods.
How to make the Mediterranean diet work for you
If you want to incorporate the Mediterranean diet into your life, Cartwright says to start with plenty of fruits and veggies, then add some unsalted nuts, seeds and legumes to the mix. Sprinkle in plenty of antioxidant-rich spices like curry, cinnamon, paprika, cumin, turmeric and ginger. Add fatty fish two to three times a week. Switch to olive oil for cooking and homemade salad dressings. Eating whole grains plus some low-fat dairy are great ways to get started with this Mediterranean-inspired meal plan.
This story was originally published in September 2014 and has been updated with new information.