Dieters have been told to eat like cavemen (the Paleo diet), slurp liquefied vegetables ("green smoothies") and learn to love bread that tastes like sawdust (aka gluten-free).
Fortunately, the pendulum is swinging back toward a more palatable recipe for health: the Mediterranean diet.
The "eat like a Greek" approach had a false start in the mid-1990s, until it was usurped by the low-fat craze. But thanks to a bumper crop of promising new studies, the Mediterranean diet has finally hit prime time. In the past year, leading medical journals have reported that the Mediterranean diet may ward against heart attack, stroke and type 2 diabetes, as well as chronic illness after the age of 70. Cardiovascular disease specialists are calling the diet a medical breakthrough.
But what, exactly, is the Mediterranean diet?
Experts acknowledge there is little consensus about what it entails – or even which foods are essential to the meal plan.
"The general public wants magic bullets," said David Jenkins, a professor of nutritional sciences at the University of Toronto. But when scientists refer to the Mediterranean diet, "we're really talking about a loose concept."
Researchers studying the diet's role in disease prevention are dealing with a large number of variables, and can draw only vague conclusions about which foods might provide health benefits, said James McCormack, a professor of pharmaceutical sciences at the University of British Columbia.
Could it be the olive oil, rich in oleic acid? The antioxidants in the red white? The probiotics in the yogurt? Or a combination of these elements? If so, what is the optimal ratio of each?
"It's an almost unanswerable question," McCormack said.
But nutritionists generally agree that the Mediterranean diet is a far cry from the heaping plates of pasta at an Italian restaurant, or the skewered meat platters at a Greek taverna.
Rather, the "Mediterranean diet" title was coined to describe the typical diet in Crete or southern Italy in the early 1960s, when villagers of the region had among the highest life expectancies and lowest chronic disease rates in the world. Cretans reportedly ate mostly plant-based foods; moderate amounts of cheese, yogurt, fish, poultry, eggs and red wine; and very little red meat.
Villagers got as much as 40 per cent of their calories from fat, mostly in the form of olive oil, which makes the diet sound rich and hearty. But champions of the Mediterranean way often fail to mention that Cretans were very active physically – and much leaner than their North American counterparts.
"We are hungry most of the time," a villager lamented during a 1948 study of Cretan dietary patterns sponsored by the Rockefeller Foundation. Cretan farmers told the researchers that if they could change their diet, they would add more meat, fish, butter and pasta. In other words, they would ditch their Mediterranean diet in a heartbeat.
Because few North Americans would sign up for a traditional peasant diet that included servings of coarse grain mush, a modified version is clearly in order. But research about the benefits of a modified Mediterranean diet is still in the early stages, and definitions of the diet have been all over the map.
Last year, a headline-grabbing Spanish study of the diet, published in the New England Journal of Medicine, found that Spaniards who ate extra nuts or olive oil – a whopping four tablespoons of oil per day – had a 30-per-cent reduction in the risk of heart attacks and strokes, when compared with a control group. But other than measuring markers of olive oil and nut consumption in blood and urine samples, researchers had little way of knowing just how closely participants had followed the recommendation to eat a traditional Mediterranean diet.
In another study, published early this month in the online journal Plos One, Harvard University researchers analyzed the dietary habits of firefighters in the U.S. Midwest. They concluded that the more closely participants followed the Mediterranean diet, the less likely they were to have risk factors for heart disease, such as high cholesterol. In the study, however, the researchers noted that the firefighters consumed little to no fish, red wine, nuts or legumes – the widely regarded staples of Mediterranean cuisine.
With definitions this loose, how is a person supposed to follow a Mediterranean diet?
The answer is to eat a wide variety of minimally processed foods to cover all the nutritional bases, Jenkins said. The beauty of a Mediterranean-style diet, he said, is that it includes less of the foods associated with disease (such as processed meats) and more of those linked to good health, including fruits and vegetables high in vitamins and fibre; cold-pressed vegetable oils that increase "good" cholesterol; and small amounts of cultured dairy products, such as yogurt and cheese, which promote gut health.
Rather than dividing foods into nutrient categories, "we have to start lumping good things together," he said.
Jenkins is currently applying for funding to set up the Canadian arm of a follow-up study conducted by the Spanish researchers. The goal is to study how participants respond to a more intensive Mediterranean-diet treatment – including regular exercise, dietary advice and group support – and to determine whether a modified Mediterranean diet can help prevent disease on both sides of the Atlantic.
With any luck, Jenkins said, "these sorts of dietary approaches will be shaping the way we eat for many years to come."