The Mediterranean Diet or a Whole Food Plant-Based Diet?

Michael Greger M.D. FACLM · February 27, 2015 · Volume 23

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A randomized controlled trial found that a Mediterranean-type diet can dramatically lower the risk of subsequent heart attacks. How does it compare with plant-based diet data?

Discuss

Transcript

Recent studies have shown that higher Mediterranean diet adherence scores are associated with a significant reduction of the risk of death, heart disease, cancer and brain disease. But the problem with population studies like these is that people who eat healthier may also live healthier, and so how do we know it’s their diet? As the American Heart Association position states: “Before advising people to follow a Mediterranean diet, we need more studies to find out whether the diet itself or other lifestyle factors account for the lower deaths from heart disease.” How do you do that? Well there are ways you can control for obvious things like smoking and exercise, which many of the studies did, but ideally you’d do an interventional trial, the gold standard of nutritional science. Take people, change their diet, while trying to keep everything else the same, and see what happens. And that’s what we got 20 years ago, the famous Lyon Diet Heart Study. About 600 folks who had just had their first heart attack were randomized into two groups. The control group got no dietary advice, apart from whatever their doctors were telling them, but the experimental group was told to eat more of a Mediterranean-type diet, supplemented with a canola-oil based spread to give them the plant-based omega-3s they’d normally be getting from eating weeds and walnuts if they actually lived on a Greek isle in the 1950s.

The Mediterranean diet group did end up taking some of the dietary advice to heart. They ate more bread, more fruit, less deli meat, less meat in general, and less butter and cream, but other than that no significant changes in diet were reported in terms of wine, olive oil, or fish consumption. So less saturated fat and cholesterol, more plant-based omega 3s, but not huge dietary changes. But at the end of about four years, in the control group, 44 individuals had a second heart attack, either fatal or nonfatal, but only 14 suffered another attack in the group that changed their diet. So they went from having like a 4% chance of having a heart attack every year, down to like 1%.

Now a cynic might say yes, less death and disease, but the Mediterranean diet continued to feed their heart disease, so much so that 14 of them suffered new heart attacks while on the diet. Now their disease progressed a lot less than the regular diet group, about four times less, but what if there were a diet that could stop or reverse the disease?

Dr. Caldwell Esselstyn and colleagues at the Cleveland Clinic recently published a case series of 198 consecutive patients with cardiovascular disease counseled to switch to a diet composed entirely of whole plant foods. Of the 198, 177 stuck to the diet, whereas the other 21 fell off the wagon, setting up kind of a natural experiment. What happened to the 21? This was such a sick group of patients that more than half suffered from a fatal heart attack, or needed angioplasty, or a heart transplant. In that same time period of about four years, of the 177 who stuck to the plant-based diet only one had a major event as a result of worsening disease. Not half, but less than 1%. As Dean Ornish noted in his response to the latest Mediterranean trial, “A Mediterranean diet is better than what most people are consuming; even better may be a diet based on whole foods and plants.”

Now this was not a randomized trial, so it can’t be directly compared to the Lyon study, and it included very determined patients. Not everyone is willing to dramatically change their diets, even if it may literally be a matter of life or death. In which case, rather than doing nothing, eating a more Mediterranean-type diet may cut risk for heart attack survivors by about two thirds. Cutting 99% of risk would be better, if Esselstyn’s results were replicated in a controlled trial, but even a 70% drop in risk could save tens of thousands of lives every year.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

Please consider volunteering to help out on the site.

Sources

Acknowledgements

Images thanks to Chris Coleman via Flickr.

Recent studies have shown that higher Mediterranean diet adherence scores are associated with a significant reduction of the risk of death, heart disease, cancer and brain disease. But the problem with population studies like these is that people who eat healthier may also live healthier, and so how do we know it’s their diet? As the American Heart Association position states: “Before advising people to follow a Mediterranean diet, we need more studies to find out whether the diet itself or other lifestyle factors account for the lower deaths from heart disease.” How do you do that? Well there are ways you can control for obvious things like smoking and exercise, which many of the studies did, but ideally you’d do an interventional trial, the gold standard of nutritional science. Take people, change their diet, while trying to keep everything else the same, and see what happens. And that’s what we got 20 years ago, the famous Lyon Diet Heart Study. About 600 folks who had just had their first heart attack were randomized into two groups. The control group got no dietary advice, apart from whatever their doctors were telling them, but the experimental group was told to eat more of a Mediterranean-type diet, supplemented with a canola-oil based spread to give them the plant-based omega-3s they’d normally be getting from eating weeds and walnuts if they actually lived on a Greek isle in the 1950s.

The Mediterranean diet group did end up taking some of the dietary advice to heart. They ate more bread, more fruit, less deli meat, less meat in general, and less butter and cream, but other than that no significant changes in diet were reported in terms of wine, olive oil, or fish consumption. So less saturated fat and cholesterol, more plant-based omega 3s, but not huge dietary changes. But at the end of about four years, in the control group, 44 individuals had a second heart attack, either fatal or nonfatal, but only 14 suffered another attack in the group that changed their diet. So they went from having like a 4% chance of having a heart attack every year, down to like 1%.

Now a cynic might say yes, less death and disease, but the Mediterranean diet continued to feed their heart disease, so much so that 14 of them suffered new heart attacks while on the diet. Now their disease progressed a lot less than the regular diet group, about four times less, but what if there were a diet that could stop or reverse the disease?

Dr. Caldwell Esselstyn and colleagues at the Cleveland Clinic recently published a case series of 198 consecutive patients with cardiovascular disease counseled to switch to a diet composed entirely of whole plant foods. Of the 198, 177 stuck to the diet, whereas the other 21 fell off the wagon, setting up kind of a natural experiment. What happened to the 21? This was such a sick group of patients that more than half suffered from a fatal heart attack, or needed angioplasty, or a heart transplant. In that same time period of about four years, of the 177 who stuck to the plant-based diet only one had a major event as a result of worsening disease. Not half, but less than 1%. As Dean Ornish noted in his response to the latest Mediterranean trial, “A Mediterranean diet is better than what most people are consuming; even better may be a diet based on whole foods and plants.”

Now this was not a randomized trial, so it can’t be directly compared to the Lyon study, and it included very determined patients. Not everyone is willing to dramatically change their diets, even if it may literally be a matter of life or death. In which case, rather than doing nothing, eating a more Mediterranean-type diet may cut risk for heart attack survivors by about two thirds. Cutting 99% of risk would be better, if Esselstyn’s results were replicated in a controlled trial, but even a 70% drop in risk could save tens of thousands of lives every year.

To see any graphs, charts, graphics, images, and quotes to which Dr. Greger may be referring, watch the above video. This is just an approximation of the audio contributed by Katie Schloer.

Please consider volunteering to help out on the site.

Images thanks to Chris Coleman via Flickr.

Doctor's Note

This is the second of a six-part video series on the Mediterranean diet. For some historical backdrop, check out out the first one at Why Was Heart Disease Rare in the Mediterranean? Here are the next four to come:

For more on Dr. Esselstyn’s amazing work:

If the short-chain plant-based omega-3s in flax seeds and walnuts appear so beneficial, what about the long-chain omega-3s found in fish and fish oil? There are pros and cons. See, for example, Mercury vs. Omega-3s for Brain Development and Is Fish Oil Just Snake Oil?

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