What accounts for the benefits of a Mediterranean-style diet? An anatomy of health effects was published, and the single most important component was the high consumption of plant foods. In contrast, fish and seafood consumption, the only animal foods promoted in the Mediterranean diet, did not seem to help.
If you look at four of the major dietary quality scoring systems, which have all been associated with extending lifespan and lowering heart disease and cancer mortality, they all share only four things in common: more fruit, more vegetables, more whole grains and more nuts and beans. They are all built on a common core of a diet rich in plant foods, whereas opposite food patterns, rich in animal foods and poor in plant-based foods (in other words, the Western diet), is associated with higher risks. So we need to optimize the food environment to support whole grains, vegetables, fruit and plant-based proteins.
That's one of the things all the so-called Blue Zones have in common: the longest living populations have not only social support and engagement and daily exercise, but nutritionally they all center their diets around plant foods, reserving meat mostly for special occasions. In fact, the population with perhaps the highest life-expectancy in the world, the California Adventist vegetarians, doesn't eat any meat at all.
So if the primary benefits of the Mediterranean diet are due to all the whole plant foods, what if you went back to the famous PREDIMED study and created a "provegetarian" scoring system? We know vegetarians live longer, but because a pure vegetarian diet might not easily be embraced by many individuals, maybe it would be easier to swallow if we just tell people more plant-based foods and less animal-based foods. But would just moving along the spectrum towards more plants actually enable people to live longer? Researchers thought of this food pattern as a "gentle approach" to vegetarianism, figuring that if it improved survival it would be an easily understandable message for health promotion: more plant foods, less animal foods.
On this scoring system, you get points for eating fruit, vegetables, nuts, grains, beans, olive oil and potatoes, but get docked points for any animal fats, eggs, fish, dairy or any type of meat or meat products. Of course that means you get a higher score the more potato chips and French fries you eat. That's why I prefer the term "whole-food, plant-based diet" since it's defined by what you eat, not by what you don't eat. When I taught at Cornell I had "vegan" students who apparently were trying to live off French fries and beer; vegan does not necessarily mean health-promoting.
But did the provegetarian scoring system work? Regardless of healthy versus unhealthy, if you give points to people for any kind of plant food, processed or not, and detract points for any kind of animal product consumption, people with higher scores live longer. The maximum provegetarian score is 60, but even just scoring 40 or more was associated with a 40 percent drop in mortality. In fact, there were so few deaths in the highest category of adherence to the provegetarian diet, they had to merge the two upper categories for their analysis. This is evidence that simple advice to increase the consumption of plant-derived foods with reductions in the consumption of foods from animal sources confers a survival advantage. You can view the graph in my video Do Flexitarians Live Longer?
The researchers conclude, "this modest change is realistic, affordable, and achievable because a sizable proportion of their population was already eating that way. So one can get significant survival benefit without a radical shift to the exclusive consumption of plant foods, a more gradual and gentle approach which is more easily translatable into public policy." A 41 percent drop in mortality rates in the United States would mean saving the lives of hundreds of thousands of Americans every year.
Here are some of my previous videos on the Mediterranean diet:
- Why Was Heart Disease Rare in the Mediterranean?
- The Mediterranean Diet or a Whole Food Plant-Based Diet?
- PREDIMED: Does Eating Nuts Prevent Strokes?
- Improving on the Mediterranean Diet
- Mediterranean Diet & Atherosclerosis
I've done a few videos on the health of so-called semi-vegetarians or flexitarians ("flexible" vegetarians). See how they rate in:
- Plant-Based Diets and Diabetes
- Fibromyalgia vs. Mostly Raw & Mostly Vegetarian Diets
- Preventing Cataracts with Diet
- Dietary Treatment of Crohn's Disease
- Metabolic Syndrome and Plant-Based Diets
- Never Too Late to Start Eating Healthier
- Switching from Beef to Chicken & Fish May Not Lower Cholesterol
The Provegetarian Score reminds me of the animal to vegetable protein ratio in Prostate Cancer Survival: The A/V Ratio. My favorite dietary quality index is the one in Calculate Your Healthy Eating Score. How do you rate? Even the healthiest among us may be able to continue to push the envelope.
Michael Greger, M.D.
PS: If you haven't yet, you can subscribe to my free videos here and watch my live, year-in-review presentations:
- 2012: Uprooting the Leading Causes of Death
- 2013: More Than an Apple a Day
- 2014: From Table to Able: Combating Disabling Diseases with Food
- 2015: Food as Medicine: Preventing and Treating the Most Dreaded Diseases with Diet
- 2016: How Not To Die: The Role of Diet in Preventing, Arresting, and Reversing Our Top 15 Killers
Image Credit: Sally Plank / Flickr. This image has been modified.