You’ve surely seen plenty of headlines proclaiming the Mediterranean Diet among the healthiest ways to eat. What does the research behind these headlines mean about potential to reduce your risk of cancer? We need to step in and look more closely at these studies, and also step back to view their findings as part of the big picture on what we know about eating habits and cancer risk.
Does a Mediterranean Diet reduce cancer risk?
A growing number of studies do link a Mediterranean pattern of eating with lower cancer risk. But it’s important to emphasize that this is compared to people with low scores for “Mediterranean” eating –which usually means they have eating habits that include more meat, refined grains and sweets. These studies do not establish Mediterranean diets as more protective than other healthy ways of eating.
What is a Mediterranean Diet?
One of the common scoring systems used to rate eating habits in studies that follow people for many years is called the Alternate Mediterranean Diet Score (often called “aMED” for short). A higher score reflects eating more of some foods (vegetables, fruits, whole grains, dried beans and peas, nuts, fish), and less of others (red and processed meats). A point is also awarded for a greater proportion of dietary fat as monounsaturated fat (like that found in olive oil, as well as in avocados, canola oil and many nuts) rather than saturated fat. And a point is also given for alcohol consumption within a range equivalent to 2 to 7 standard drinks/week for women or 5 to 12 for men.
What Mediterranean Diet Research Means – and Doesn’t Mean
Foreign foods and expensive ingredients aren’t needed: Look again at how the aMED is scored. You can score just as high with meals that include a Chinese stir-fry, Japanese sushi and Latin American beans and rice as with purely “Mediterranean” cuisine.
Eating more vegetables, fruits, whole grains, beans and nuts is at the core of this diet, regardless of how you flavor them and which specific foods you choose.
Healthy fat, more than high-fat: By tradition, Mediterranean cuisine is often relatively high in fat, thanks to liberal use of olive oil. But in the aMED scoring that defines the diet in many health-related studies, points are earned for healthy forms of fat as a larger part of the diet than saturated fat, not for using more fat. In the PREDIMED trial conducted in Spain and in some observational studies, a greater proportion of calories coming from olive oil is associated with lower risk of some cancers. Indeed, extra-virgin olive oil contains phenolic compounds and tocopherols (compounds related to vitamin E) that may be cancer-protective. However, this suggests potential benefit from swapping olive oil for calories from less healthful foods, not just adding more fat (and thus calories). AICR Continuous Update Project reports link excess weight and weight gain with greater risk of at least 11 different cancers, so an eating pattern that reduces cancer risk needs to be one the helps you reach and maintain a healthy weight.
Wine in moderation as optional, not essential: We often hear that red wine, a common part of the culture in many areas of the Mediterranean, may offer cancer-protective benefits through the resveratrol compounds it contains. However, although studies in isolated cells and animals show exciting potential for anti-cancer effects, there are far fewer human studies, most of which have investigated safety and bioavailability of different doses of isolated resveratrol, not the effectiveness of resveratrol against cancer.
What these scores have in common is that all reflect eating habits that focus on nutrient-rich plant foods as the largest part of the plate.
In the Million Women study, researchers found no difference in the increased risk of cancer among women whose only alcohol consumption was wine than among women who drank other alcoholic beverages — and this was true regardless of whether their wine choice was red, white or both. A pooled analysis of 20 studies following women from 6 to 16 years similarly found that the increased risk of breast cancer associated with alcohol consumption was no different for wine than for beer or liquor.
One Plant-Based Approach, Not The Only One
Higher Mediterranean diet scores were linked with about 15-20 percent fewer deaths from cancer compared to people with lowest scores in an analysis of three large U.S. studies that followed people for many years. However, similar results were seen in the same subjects who had scores showing eating habits that more closely resembled the 2010 Dietary Guidelines for Americans or a DASH-style diet. What these scores have in common is that all reflect eating habits that focus on nutrient-rich plant foods as the largest part of the plate.