Why the Mediterranean Diet Is so Successful

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Story at-a-glance -

  • A number of studies have confirmed the health benefits of a Mediterranean-style diet — most of which are likely due to it being low in sugars, moderate in protein and high in fresh fruits and vegetables, along with healthy fats
  • Eating a Mediterranean-style diet has been linked to a number of health benefits, including prevention and reversal of metabolic syndrome, improved cardiovascular health and reduced risk for stroke
  • Other benefits include reduced risk of adult acne, rheumatoid arthritis, Parkinson's, Alzheimer's disease and cancer, and improved overall health and longevity

By Dr. Mercola

The Mediterranean diet is one that has managed to maintain popularity through changing fads, and for good reason. A number of studies have confirmed its health benefits — most of which are likely due to it being low in sugars, moderate in protein and high in fresh fruits and vegetables, along with healthy fats.

Contrary to popular belief, there's actually no single "Mediterranean diet." At least 16 countries border the Mediterranean Sea, and dietary habits vary from country to country due to differences in culture, ethnic background, religion and agricultural production.

That said, a primary hallmark of a Mediterranean-style diet is a focus on whole, minimally processed foods. The emphasis on fresh vegetables alone makes it far healthier than the standard American diet, which is very high in processed foods.

Health Benefits Associated With a Mediterranean-Style Diet

Eating a Mediterranean-style diet has been linked to a number of health benefits, including:

Prevention and/or reversal of metabolic syndrome, a cluster of risk factors for heart disease and diabetes.

One review of 35 clinical trials found it helped reduce belly fat and high blood pressure, elevate HDL cholesterol and improve blood sugar levels, compared to those who ate a low-fat diet.1

Improved cardiovascular health and a significantly reduced risk of stroke — effects linked to higher amounts of animal-based omega-3 fats (primarily from fish).2,3

According to recent research, marine animal-based omega-3 may lower your risk of heart disease even if you're already at increased risk due to high levels of low-density lipoprotein (LDL) cholesterol and/or triglycerides.4,5

Higher levels of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) from seafood or supplements was associated with a 16 percent lower risk of heart disease in those with high triglycerides, and a 14 percent reduced risk in those with high LDLs.

Reduced risk of acne in adult women. According to recent research, adult women who ate fresh fruits, vegetables and fish less than four days a week had double the risk of adult acne.6,7

Reduced risk of rheumatoid arthritis,8 Parkinson's, Alzheimer's disease and cancer.9

Improved overall health and longevity. In one study, women who closely followed a Mediterranean-style diet in their 50s and 60s were 46 percent more likely to live past the age of 70 without chronic illness or cognitive problems.10

Mediterranean Diet Linked to Healthier Brain

Overall, the Mediterranean diet is one of the best conventional diets for brain and heart health. For example, research has shown diets rich in healthy fats from nuts, avocados and olive oil may boost memory and cognition in older adults.11,12

Previous research has also suggested a Mediterranean diet may lower your odds of Alzheimer's disease, but it wasn't clear whether the diet was responsible, or if people who eat this way also make many other healthier lifestyle choices that decrease their risk.

In an effort to shed more light on the potential links between diet and cognition, the researchers randomly assigned nearly 450 seniors with risk factors for cardiovascular disease — such as overweight, high blood pressure and/or high cholesterol — to follow one of three diets:13,14

  • A Mediterranean diet supplemented with 1 liter of extra virgin olive oil per week
  • A Mediterranean diet supplemented with 30 grams of nuts a day
  • A low-fat diet

Brain function tests were conducted before and after the study. Those following a Mediterranean diet with supplemental nuts showed significant improvement in memory, while those who got supplemental olive oil experienced significantly improved cognition.

The low-fat group, on the other hand, experienced a significant decrease in both memory and cognitive function.

Older Adults Suffer Less Brain Shrinkage on Mediterranean Diet

More recently, scientists found that a Mediterranean-style diet also helps reduce age-related brain shrinkage in older adults. As reported by the LA Times:15

"In a group of 562 Scots in their 70s, those whose consumption patterns more closely followed the Mediterranean diet experienced, on average, half the brain shrinkage that was normal for the group as a whole over a three-year period …

The researchers used the food-frequency surveys to divide the group into two — those who at least approximated a Mediterranean-style diet and those who came nowhere close.

Even though many in the Med-diet group were far from perfect in their adherence, the average brain-volume loss differed significantly between the two groups."

Your Brain Needs Healthy Fats for Optimal Function

Results such as these certainly make sense when you consider how important healthy fats are for your brain function. After all, your brain is composed of at least 60 percent fat — the most important of which is DHA, found in seafood such as clean fish and krill oil. That said, it's important to choose your seafood wisely.

What you're looking for are fish high in healthy fats, such as omega-3, while also being low in mercury and other environmental pollutants. Good choices include smaller fatty fish like sardines, anchovies and herring.

As a general rule, the lower on the food chain the fish is, the less likely it is to contain harmful levels of contaminants. Many of these smaller fish also contain higher amounts of omega-3, so it's a win-win. Wild-caught Alaskan salmon is another healthy choice. If you avoid fish, it's important to take a high-quality omega-3 supplement such as krill oil.

Besides fish, other examples of beneficial fats that your body (and your brain in particular) needs for optimal function include avocado, organic grass-fed raw butter, clarified butter called ghee, olives, organic virgin olive oil and coconut oil, nuts like pecans and macadamia and free-range eggs.

It's also important to avoid sugars and processed grains. Research from the Mayo Clinic shows diets rich in carbohydrates are associated with an 89 percent increased risk for dementia, while high-fat diets are associated with a 42 percent reduced risk.16

Omega-3 Is Important for Other Psychiatric Conditions as Well

Animal-based omega-3 in combination with vitamin D has also been shown to improve cognitive function and behavior associated with certain psychiatric conditions, including ADHD, bipolar disorder and schizophrenia — in part by regulating your brain's serotonin levels.17,18,19

The omega-3 fat EPA reduces inflammatory signaling molecules in your brain that inhibit serotonin release from presynaptic neurons, thereby boosting your serotonin levels. DHA — which is an important structural component of your brain cells — also has a beneficial influence on serotonin receptors by increasing their access to serotonin.

Other diets shown to be particularly beneficial for brain health include the DASH and the MIND diets,20 the latter of which emphasizes fruits and vegetables, especially leafy greens and berries, whole grains, nuts, olive oil, beans, poultry and fish, while limiting red meat, cheese, butter, sweets and fried foods.

What these three diets have in common is an emphasis on whole foods, particularly fresh fruits and vegetables, and at least SOME healthy fats. Considering the importance of eating real food, it's not so surprising that the DASH diet, Mediterranean diet and MIND diet rank No.1, 2 and 3 respectively as the best overall diets for good health, according to a panel of health experts.21

Benefits of the DASH Diet

The DASH diet in particular has been shown to be quite effective for lowering your risk of hypertension. However, I believe the real reason for this effect is not due to the reduction in salt but rather the reduction in processed foods, which is high in fructose.22,23 As your insulin and leptin levels rise in response to net carbs, it causes your blood pressure to increase.

Excess fructose promotes hypertension to a far greater degree than excess salt. One 2010 study24 discovered that those who consumed 74 grams or more per day of fructose (the equivalent of about 2.5 sugary drinks) had a 77 percent greater risk of having blood pressure levels of 160/100 mmHg (stage 2 hypertension). Consuming 74 grams or more of fructose per day also increased the risk of a 135/85 blood pressure reading by 26 percent, and a reading of 140/90 by 30 percent.

Elevated uric acid levels are also significantly associated with hypertension (by inhibiting nitric oxide in your blood vessels), and fructose elevates uric acid. In fact, uric acid is a byproduct of fructose metabolism. So, by eliminating excess sugar and fructose from your diet, you effectively address root issues that contribute to high blood pressure.

I recommend keeping your total fructose consumption below 25 grams per day. If you're insulin resistant (about 80 percent of Americans are), have high blood pressure, diabetes, heart disease or other chronic disease, you'd be wise to limit your fructose to 15 grams or less per day, until your condition has normalized.

As for the issue of salt (which the DASH diet restricts), it's important to realize that salt is actually essential for maintaining and regulating blood pressure. The key is to use the right kind of salt. Ideally, replace all processed table salt with a natural unprocessed version, such as Himalayan salt, which contains a variety of trace minerals your body actually needs.

Part of the DASH diet's effectiveness for hypertension may also have to do with the fact that it focuses on vegetables, which helps improve your sodium-to-potassium ratio. Your body needs potassium to maintain proper pH levels in your body fluids, and it plays an integral role in regulating your blood pressure. It's actually possible that potassium deficiency may be a greater contributor to hypertension than excess sodium (but not likely a greater factor than fructose). 

Mediterranean Diet May Cut Your Heart Disease Risk by Nearly One-Third

The importance of healthy fats cannot be overstated in my view. Fats are important for so many biological processes, especially those related to your brain and heart function. In the case of the latter, a Spanish trial,25 which included nearly 7,450 volunteers between the ages of 55 and 80, was stopped early for ethical reasons as the low-fat control group was deemed to be at a dangerous disadvantage.

The participants had all been diagnosed with high risk of cardiovascular disease, but were asymptomatic at the outset of the study. Participants were followed for a median of 4.8 years. The volunteers were randomly divided into three groups (two intervention groups and one control):

  • Mediterranean diet rich in fresh vegetables, fruits, seafood, whole grains and mono-unsaturated fats, very low in meat and dairy and supplemented with 30 grams (1.05 ounces) of nuts per day (15 grams walnuts, 7.5 grams almonds and 7.5 grams hazelnuts)
  • Mediterranean diet (as above) supplemented with 50 milliliters (1.7 ounces) of virgin olive oil per day instead of nuts
  • Low-fat diet (control)

There were no calorie restrictions for any of the groups, nor was physical activity promoted or required. Compliance with olive oil and nut consumption was tested via blood and urine analysis. The primary end point was a composite of myocardial infarction, stroke and death from cardiovascular causes. Secondary end points were stroke, myocardial infarction, death from cardiovascular causes and death from any cause.

Remarkably, in less than five years, the two intervention groups achieved a 30 percent relative risk reduction for cardiovascular disease, and stroke reduction was an impressive 49 percent. No wonder they felt the trial had to be stopped for ethical reasons!

Sadly, low-fat diets remain among the most accepted diets in the medical community, both for weight management and cardiac health. There's no telling how many millions of people have prematurely died from this fatally flawed and scientifically-refuted advice.

Are You Eating Enough Fish?

According to the latest report26 by the National Oceanic and Atmospheric Administration (NOAA), Americans increased their seafood consumption by nearly 1 pound per person in 2015, to an average of 15.5 pounds per year, or just over 4.75 ounces per week.

That's the largest increase in seafood consumption in two decades, yet we still fall short of dietary recommendations, which call for 8 ounces of seafood per week. Ideally, aim for two to three servings of fish like salmon or sardines, anchovies, mackerel and herring each week, to obtain healthy levels of omega-3. Avoid canned tuna, mackerel, swordfish, grouper, marlin, orange roughy, snapper and halibut, as they have some of the highestlevels of contamination.

For more information about mercury in fish, see the Mercury Policy Project's website, "Mercury and Fish: The Facts."27 They have a helpful guide you can print out for reference.28 A 2015 article in Investigate West also addressed this issue, and includes a guide to how many meals per week you can safely eat based on any given seafood's contamination level.29

Why Higher Fish Consumption Is Likely Part of Mediterranean Diet's High Success Rate 

Besides omega-3 fats and other valuable nutrients, fish is also a good source of high-quality protein. However, most fish contain only HALF of the protein found in beef and chicken, and this is actually a very good thing. While we do need protein for muscle, bone and hormone health, eating more than your body actually needs can stimulate your mammalian target of rapamycin (mTOR) — a pathway that plays an important role in many cancers, among other things.

In fact, Valter Longo, Ph.D.,30 — a professor of biological science at the University of California and a well-known longevity researcher — believes the reduced protein content in fish may be one reason why the Mediterranean diet is linked to life extension and reduced risk for chronic disease. In essence, those who eat more fish than red meat automatically get far less protein, thereby preventing the excessive stimulation of mTOR.

For Health and Longevity, Be Sure to Optimize Your Omega-3

If you do not eat this amount of fish on a weekly basis, consider taking a daily omega-3 supplement such as krill oil. As for dosage, the amount of omega-3s you need depends on your body size, age, health status, the type of omega-3 and more. Your best bet is to get an omega-3 index test. This test measures the omega-3 in your red blood cells, which is really the only way to determine if you're getting enough from your diet or supplements. Your index should be above 8 percent.

While there's no set recommended standard dose of omega-3 fats, some health organizations recommend a daily dose of 250 to 500 milligram (mg) of EPA and DHA for healthy adults. Higher amounts (upwards of 1,000 to 2,000 mg of EPA and DHA daily) are typically recommended for the prevention of memory loss, depression and heart disease.

If you're pregnant or breastfeeding, your body will likely require additional omega-3 fats. The American Dietetic Association and Dietitians of Canada recommend pregnant and lactating women (along with all adults) consume at least 500 mg of omega-3s, including EPA and DHA, daily.

Other Vital Reasons Why Mediterranean-Style Diet Is a Good Choice

Aside from the important dietary components mentioned above, there are at least three other lifestyle factors that contribute to the benefits achieved by those actually living in the Mediterranean countries. The obvious one is that these are subtropical countries and most people are able to achieve a healthy level of sun exposure, as the opportunities to go outside with minimal clothing on are far more frequent than for most of us living in the U.S.

The other two are related in that they are social variable. There is less reliance on cars and automated tasks that allow them to walk and be more active and mobile than many of us in the U.S. Additionally, there is an important social component to most meals that is typically not encountered in the U.S.

Is There Something Better Than the Mediterranean Diet?

If you are healthy and have an ideal body fat percentage, then the dietary choices discussed above are a sound choice, especially if you integrate the other variables discussed in the section above. 

But the sad reality is that well over 80 percent of those in the U.S. do not fit this profile, as they are either overweight, have cancer, heart disease, diabetes, autoimmune or neurodegenerative diseases. If this applies to you or someone you love, then I firmly believe you need to teach your body to burn fat as its primary fuel before you engage in this type of diet.

My new book, "Fat for Fuel," discusses how to radically limit your carb and protein intake while integrating periods of feast and famine cycling, which will help your body regain its ability to burn fat as its primary fuel. Once you normalize your weight and other conditions, and your body has regained the capacity to burn fat as your primary fuel, then it makes loads of sense to shift to a Mediterranean diet.

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