Should You Try the Mediterranean Diet? We Examine the Evidence

Should You Try the Mediterranean Diet? We Examine the Evidence
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Please Note: This article is presented for informational purposes only and is not meant to diagnose or treat any illness. If you have any health concern, see a licensed healthcare professional in person.

The Mediterranean diet has long been touted as one of the best.

In fact, U.S. News and World Report named it the best diet overall compared to 41 different diets.

The Mediterranean diet was also named the best plant-based diet, best diet for healthy eating, best diet for diabetes, and easiest diet to follow.

Some studies even suggest it can help you live longer (1, 2).

But is this diet really the best diet for you?

Here, we take a closer look at the origins of the diet and the current scientific evidence to see if the Mediterranean diet is all it’s cracked up to be.

What is the Mediterranean Diet?

The Mediterranean diet is a largely plant-based diet that draws from food traditions from countries along the Mediterranean coast.

Origins of the Mediterranean Diet

The Mediterranean diet has been studied for decades, but it’s only became popular in non-Mediterranean countries since the 1990s.

It was first introduced with the Seven Countries Study, an international epidemiological study that began in 1958 and is still active today.

The study, led by Dr. Ancel Keys, linked traditional Mediterranean diets (and specifically diets that include large amounts of olive oil) with reduced risk for coronary heart disease (3, 4).

Keys and his wife published their findings on traditional Mediterranean diets and heart health in 1975. Dr. Keys remained a Mediterranean diet advocate and an active researcher for much of his life. He died just before his 101st birthday.

The Mediterranean diet as we know it today isn’t necessarily the same as the traditional diet described by Dr. Keys. This is because there are many cultural traditions that influence the cuisine in each of the 18 countries that border the Mediterranean Sea.

As such, the newer, more popular version of the Mediterranean diet—published by Walter Willett of Harvard University and Greg Drescher of the Oldways Preservation and Exchange Trust—may not include ingredients that are staples in certain Mediterranean cultures.

Today’s version also includes ingredients that wouldn’t technically be part of a traditional Mediterranean diet. Examples include avocados and quinoa, both of which are thought to have originated in South America (5).

That’s not to say that the modern version is bad, but these subtle differences may result in different health outcomes than what has been found in the Seven Countries Study.

The Mediterranean Diet Pyramid

Today’s Mediterranean diet still encourages heavy consumption of plant foods.

Fruits, vegetables, whole grains, legumes, extra virgin olive oil, beans, nuts, seeds, herbs and spices are eaten at most meals.

The primary animal proteins come from fish and seafood, which should be eaten at least twice per week. One serving of poultry, cheese, eggs, or yogurt is permitted per day, while meats and sweets are to be eaten only occasionally.

Red wine is the preferred alcoholic drink on the Mediterranean diet. Men are allowed up to 10 oz of alcohol per day, while women are allowed up to 5 oz (150 ml) per day. Any alcoholic drinks should be enjoyed with meals (6).

Fried foods, processed meats, sugar-sweetened drinks, refined grains and other foods typical of a Western-style diet should be avoided.

You may notice an extra level on the bottom of the Mediterranean Diet pyramid. This is dedicated to physical activity and companionship, important parts of the Mediterranean lifestyle.

The Mediterranean Diet Pyramid was created by a nonprofit organization called Oldways Cultural Food Traditions, in partnership with the World Health Organization and the Harvard School of Public Health.

Daily exercise is encouraged, and meals should be shared with others as often as possible.

Summary: The Mediterranean diet that’s popular today was adapted from the work of Dr. Ancel Keys, who linked diets high in fat, specifically olive oil, with lower risk for coronary heart disease. Today’s Mediterranean diet includes a variety of fruits, vegetables and grains, as well as unsaturated fats and fish. Alcohol, poultry, eggs and fermented dairy are permitted in moderation. Daily exercise and enjoying meals with others is also strongly encouraged.

Key Nutrients on the Mediterranean Diet

The Mediterranean diet is abundant in vitamins and minerals.

However, a few key nutrients—including antioxidants, polyphenols, and unsaturated fats—are thought to play special roles in the diet’s success. These nutrients appear to be more powerful when paired together, rather than in isolation (7).

Antioxidants

Antioxidants are natural chemicals found in foods that help prevent cell damage, and can be credited with many of the health benefits of the Mediterranean Diet.

Antioxidant foods (but not necessarily supplements) have a well-established role in preventing and reversing chronic disease, including cardiovascular disease and cancer.

Plant foods like fruits and vegetables contain significantly more antioxidants than animal foods. Because it includes a variety of plant foods, the Mediterranean diet is naturally high in antioxidants (8, 9).

Researchers for one large study looked at the relationship between the Mediterranean diet and antioxidants, using a small subgroup of volunteers. In this analysis, volunteers following a Mediterranean diet had higher antioxidant activity than those on a low-fat control diet (10).

Polyphenols

Polyphenols are antioxidant-rich chemicals that are found in plants.

They’re thought to protect against cardiovascular disease, cancer, and diabetes, among other health conditions. The mechanisms for this aren’t fully understood yet.

However, animal and test tube studies suggest that polyphenols may inhibit the production and release of inflammatory chemicals like cytokines (11).

Man Makes Incredible Discovery At Ark's Final Resting Place
Man Makes Incredible Discovery At Ark's Final Resting Place

Examples of polyphenols include phenolic acids, flavonoids, resveratrol, and anthocyanins. In the Mediterranean diet, these are found in olive oil, red wine, fruit, and vegetables (12).

Unsaturated Fats

The Mediterranean diet is rich in unsaturated fats, which are found in olive oil, nuts, seeds, avocados, and fish.

Studies suggest that unsaturated fats are healthier for the heart than saturated fats, like those found in meat and dairy.

Omega-3 fatty acids are thought to be especially beneficial in reducing inflammation and lowering heart risk.

Some studies have linked moderate consumption of fish, a key source of omega-3 fatty acids, with lower blood pressure and healthier blood lipid profiles, regardless of the overall dietary pattern.

However, at least two large observational studies found no strong links between eating fish and better heart health. Clinical trials would help clarify the relationship between fish and cardiovascular health (13).

Summary: The Mediterranean diet is abundant in vitamins and minerals due to its focus on plant foods. Antioxidants, polyphenols and unsaturated fats are thought to be the key nutrients responsible for disease prevention, especially when consumed together.

How Does the Mediterranean Diet Differ from Other Diets?

There are many popular diets that claim to boost health and promote weight loss, so what makes the Mediterranean diet different?

Let’s take a look at how it stacks up nutritionally when compared to keto and low-fat diets.

The Mediterranean Diet vs. the Keto Diet

The ketogenic (“keto”) diet has become especially trendy in recent years.

It typically includes around 75% of calories from fat, 20% from protein and 5% from carbohydrates. This macronutrient ratio can put the body into a metabolic state called ketosis, in which the body burns stored fats for energy instead of carbs.

Fans of the keto diet believe that it promotes weight loss and heart and brain health, among other benefits. However, the diet remains somewhat controversial.

First, there aren’t enough strong human studies to support these health claims. It’s also not clear whether some of the health benefits experienced are because of the keto diet itself or from weight loss in general (14, 15).

There are also versions of the keto diet that are very high in saturated fats and very low in fiber, both of which could compromise heart health.

The Mediterranean diet, by contrast, is moderate in fat and higher in carbohydrates. Most meals include whole grains, vegetables and/or fruit.

Fat isn’t exactly restricted on the Mediterranean diet, but typically accounts for 30-45% of calories—much lower than the keto diet (6).

The Mediterranean Diet vs. Low-Fat Diets

Low-fat diets have been popular for decades, for both weight loss and disease prevention.

The general consensus is that a low-fat diet contains less than 30% of calories from fat.

They’ve long been considered the gold standard for prevention and treatment of heart disease. However, newer studies suggest that diets rich in unsaturated fats can be heart-healthy, even when more than 30% of calories come from fat (16).

The Mediterranean diet falls into this category. It isn’t naturally low-fat since it promotes liberal use of extra virgin olive oil, which contains 14 grams of unsaturated fat per tablespoon (15 ml).

Since the Mediterranean diet is less restrictive than both keto and low-fat diets, it’s a good alternative for those who enjoy flexibility and variety in their diet.

Summary: Ketogenic (“keto”) diets contain about 75% of calories from fat, 20% from protein, and 5% from carbs. Diets with less than 30% fat are generally considered to be low-fat. The Mediterranean diet has no prescribed ratio of macronutrients, though it typically falls somewhere between keto and low-fat with an intake of around 30-45% of calories mostly in the form of unsaturated fats.

About That PREDIMED Study…

In 2018, there was a major study retraction related to the Mediterranean diet.

PREDIMED (Prevención con Dieta Mediterránea) was a multicenter trial that included more than 7,400 Spanish volunteers considered to be at high risk for heart disease.

The researchers wanted to know if the Mediterranean diet could reduce the risk of stroke, heart attack or heart-related death more effectively than a low-fat diet.

The study findings were impressive. Most notably, the study found that the Mediterranean diet could cut heart disease risk by a third among those with risk factors for it.

Researchers also analyzed smaller groups of the PREDIMED sample to see if the Mediterranean diet helped prevent cancer, cognitive decline and other health problems.

Some of these smaller studies also had remarkable findings. For example, one found that the diet was significantly better than a low-fat diet at preserving cognitive function (17, 18).

That said, PREDIMED was retracted in 2018 after a physician and statistician raised concerns that the study wasn’t properly randomized. All told, more than 20% of the study volunteers may not have been randomized using research best practices (19).

Researchers from PREDIMED revised the study in 2018, noting similar findings even after excluding 1,588 volunteers from analysis. However, questions remain about the validity of the new study (20).

We’ve excluded PREDIMED from our analysis of the Mediterranean diet as much as possible, though some of the studies cited in this article may include references to PREDIMED.

Still, it’s difficult to dispute that the Mediterranean diet is a healthy diet due to its emphasis on fruits and vegetables, whole grains and healthy fats. Studies before and since PREDIMED support its value for weight loss and overall health.

Summary: PREDIMED was a large, 4+-year study that found that the Mediterranean diet could cut heart disease risk by a third. The study was retracted in 2018 after it was discovered that more than 20% of its participants hadn’t been properly randomized. This may subtract from the body of research supporting the diet, but it doesn’t change the fact that the diet is still a healthy one.

The Mediterranean Diet and Weight Loss

The Mediterranean Diet isn’t specifically known as a weight loss diet.

However, certain features of the diet make it useful for people trying to shed a few pounds:

  • The diet’s emphasis on whole grains, fruits and vegetables make it naturally high in fiber, which may improve satiety. Studies have linked adequate dietary fiber intake with lower body weight (21).
  • The diet is fairly high in monounsaturated fats, which have been shown in small studies to promote weight loss in obese women (22).
  • The variety of foods in the diet may make it easier for people to adhere to for the long-term. Dietary adherence is a key predictor of weight loss success (5, 23).

Studies have found that the Mediterranean diet can help with weight loss, or at least prevent weight gain. However, the rate of loss may not be as rapid on the Mediterranean diet as with other diet plans.

Weight loss of 4 to 10 kgs (about 9 to 22 lbs) over 12 months is fairly typical, with the greatest losses seen in those who are the most adherent and have the most weight to lose (24, 25, 26, 27).

Keep in mind that the Mediterranean diet has no specific recommendation for the percentage of carbs. Those who are looking for more weight loss may find it useful to follow a slightly lower carb version of the Mediterranean diet.

In one study of 259 overweight adults with diabetes, those who followed a low-carb Mediterranean diet consisting of 35% carbs and 45% fat lost an average of 2.7 kgs more in 12 months than those assigned to a traditional version of the diet (25).

Also, remember that you’ll gain weight on any diet if you eat more calories than you burn. You may find it helpful to track your calories for a few days if you start gaining weight on a Mediterranean diet. This can help give you a sense of where you can trim “hidden” calories from the diet.

Summary: The Mediterranean diet can help promote weight loss, partly because of its emphasis on fiber-rich foods and unsaturated fats. Those struggling to lose weight on it may benefit from a slight reduction in carbs or tracking calories for a few days.

The Mediterranean Diet and Heart Health

An estimated 22.2 million people per year will die from heart disease by 2030 (28).

About 1/3 of adults with heart disease will first have a condition called metabolic syndrome.

Metabolic syndrome is a group of symptoms that increase the risk for heart disease, diabetes and death from any cause. Symptoms include:

  • High triglycerides
  • Increased blood sugar levels
  • Abdominal obesity

In one review that included 50 studies and nearly 535,000 participants, people who followed a Mediterranean diet were 50% less likely to have metabolic syndrome (29).

What’s more, the Mediterranean diet is thought to be an effective treatment for metabolic syndrome.

One study of 180 participants with metabolic syndrome compared the Mediterranean diet with a calorie-restricted diet that included exercise. Both groups had similar ratios of protein, fat, and carbohydrates in the diet.

After 2 years, 89% of participants in the diet and exercise group still had metabolic syndrome, compared to just 51% of participants in the Mediterranean diet group.

The Mediterranean diet group also saw significant reductions in body mass index, waist circumference, body weight, blood pressure, total cholesterol, triglycerides and blood markers of inflammation, with significant boosts in HDL cholesterol (30).

In short, a Mediterranean diet can help prevent those with metabolic syndrome from developing heart disease.

But does it work in people who already have heart disease? The first randomized control trial on the Mediterranean Diet and heart health looked at this very question.

A total of 423 heart attack survivors completed the Lyon Diet Heart Study, which explored whether a Mediterranean diet could help prevent:

  • subsequent heart attacks
  • stroke
  • heart failure
  • heart-related hospitalizations.

One group of 219 volunteers received a one-hour counseling session with instruction on the Mediterranean diet. A second group of 204 volunteers received no special diet instruction beyond routine interactions with physicians and hospital dietitians.

After 46 months, the Mediterranean diet group had a 50-70% lower risk of recurrent heart disease than the control group.

However, critics of the study caution that not all participants submitted diet records. This calls into question the degree to which diet affected the outcomes in some of the volunteers (31).

Overall, most studies have found that the Mediterranean diet shows promise in warding off metabolic syndrome and managing existing cardiovascular disease. However, more studies are needed to clarify its role—especially since the PREDIMED controversy (32, 33, 34).

Summary: A large review of studies linked the Mediterranean diet with a 50% lower risk for metabolic syndrome, a precursor to heart disease. Another large study found that the diet can lower risk for recurrent heart disease by up to 70% in adults with a history of heart attack. However, other studies suggest that the diet has little to no benefit in terms of preventing heart disease, so more research is needed.

The Mediterranean Diet and Cancer

Certain risk factors for cancer, like genetics, can’t be changed.

However, in recent years, more and more cancers are being linked to modifiable risk factors. Unhealthy diets increase the odds of developing certain types of cancer, while healthy diets like the Mediterranean diet may reduce risk.

There are several reasons why the Mediterranean diet may help protect against cancer. The diet is rich in antioxidants, polyphenols, omega-3 fatty acids, and fiber. It also promotes modest, but not excessive, alcohol intake (35).

In one large review with more than 570,000 participants, 24 out of 28 clinical trials linked the Mediterranean diet with a lower risk of cancer.

The effect was especially pronounced in cancers of the digestive tract. In fact, the Mediterranean Diet significantly reduced risk for all digestive cancers, except pancreatic cancer (36).

A handful of studies have also linked Mediterranean diet adherence to lower risk for bladder and breast cancers. However, these findings have been inconsistent with breast cancer (37, 38).

Summary: Clinical trials have shown that the Mediterranean diet can lower risk for most digestive cancers, as well as bladder cancer. However, findings are inconsistent regarding its protection against breast cancer.

The Mediterranean Diet and Diabetes

A recent report suggests that 642 million adults (ages 20-79) worldwide will have diabetes by the year 2030 (39).

In some cases, diabetes can’t be prevented. However, diabetes risk is most often influenced by diet and other lifestyle factors. As such, a healthy diet is important for prevention and treatment of the disease.

The Mediterranean diet is one of several diets that can help with that. One large study found an 83% lower risk of diabetes among adults who followed a Mediterranean diet.

In one review of clinical trials, the diet was more effective than others in lowering fasting glucose and hemoglobin A1C in volunteers with type 2 diabetes (40, 41).

Researchers have proposed several mechanisms by which the Mediterranean diet may lower diabetes risk. Studies suggest that high intake of dietary polyphenols and replacing saturated fats with unsaturated fats can help your body use insulin more effectively (42, 43).

The Mediterranean diet certainly isn’t the only one that helps prevent or treat diabetes. Most diets that result in weight loss will help lower blood sugar.

However, the Mediterranean diet may be a good option for people at risk for diabetes who’ve tried other diets without success.

Summary: Studies have linked the Mediterranean diet with lower risk of type 2 diabetes. They’ve also found that a Mediterranean diet can lower blood sugar in people with existing diabetes.

The Mediterranean Diet and Brain Health

Alzheimer’s disease is a common condition in older adults that affects memory and other thinking skills.

Other adults may have some minor memory loss, which is often called mild cognitive impairment. There’s been growing interest in the relationship between diet and cognitive function, with some focus on the Mediterranean diet.

Studies have linked higher adherence with a Mediterranean diet to lower risk for Alzheimer’s disease. In one study of more than 2,200 adults, those who followed the diet most closely had a 40% lower risk for the disease than those with the lowest adherence (44).

Moreover, the diet may offer protection against mild cognitive impairment.

One study followed nearly 1,400 adults with normal cognition for 4.5 years. Those with low adherence to the Mediterranean diet had 28% greater risk of developing mild cognitive impairment compared to those who followed the diet closely.

In the same study, higher adherence to the diet also appeared to lower the risk of mild cognitive impairment progressing into Alzheimer’s disease (45).

Other studies support these findings, but most have established correlation rather than causation. Clinical trials are needed to better understand the relationship between the Mediterranean diet and cognitive function (46).

Summary: The Mediterranean diet has shown promise in lowering risk for mild cognitive impairment and Alzheimer’s disease. However, most studies on the topic have been observational and can’t prove causation. More research is needed.

Mediterranean Diet Shopping List & Meal Plan

The Mediterranean diet shopping list includes a variety of fresh fruits and vegetables, grains, nuts, seeds, herbs, spices and more.

Feel free to select ones that you love and also experiment with new ones. However, be sure to choose produce in a variety of colors. Here are some foods to include:

  • Greens
  • Cherry Tomatoes
  • Potatoes
  • Cucumbers
  • Avocado
  • Eggplant (Aubergine)
  • Peppers
  • Onions
  • Garlic
  • Broccoli
  • Cauliflower
  • Apples
  • Berries
  • Citrus Fruit
  • Lentils
  • Beans
  • Brown Rice
  • Quinoa
  • Barley
  • Farro
  • Oats
  • Olive Oil
  • Nuts
  • Seeds
  • Fish (salmon, tuna, mackerel, whitefish, shellfish, etc.)
  • Chicken
  • Eggs
  • Plain Greek Yogurt
  • Feta Cheese
  • Kefir
  • Red Wine
  • Herbs
  • Spices

7-Day Sample Mediterranean Diet Meal Plan

Ready to give the diet a try?

Here are some ideas for meals that you may enjoy on the updated version of the Mediterranean diet.

Whenever possible, meals should be enjoyed with family, friends or colleagues. Be sure to check with your doctor before adding wine, if you’re not currently a drinker.

Monday

  • Breakfast: Oatmeal with berries and almonds; black coffee, green tea or water
  • Lunch: Steamed lentils over quinoa with diced tomatoes and cucumbers and 1 ounce of feta cheese; water
  • Dinner: Grilled salmon with asparagus, brown rice, and broccoli roasted in olive oil; water or one 5 oz (150 ml) glass of red wine
  • Snack: One apple with 2 tablespoons unsweetened nut butter

Tuesday

  • Breakfast: Whole grain toast with avocado spread and bean sprouts; banana; black coffee, green tea or water
  • Lunch: Kale salad with beets, sliced almonds, mandarin oranges, parmesan cheese, grilled chicken, olive oil and balsamic vinegar; whole grain baguette dipped in olive oil; water
  • Dinner: Lentil soup; one serving of whole grain crackers; water or one 5 oz (150 ml) glass of red wine
  • Snack: 2 small squares of dark chocolate with a small handful of cashews

Wednesday

  • Breakfast: Overnight oats with unsweetened almond milk, chia seeds, and berries; black coffee, green tea or water
  • Lunch: Whole grain pita pizza (pita brushed with olive oil, topped with red pasta sauce, basil, feta cheese, and olives, then baked); small green salad; water
  • Dinner: Chickpea stir fry sauteed in olive oil; water or one 5 oz (150 ml) glass of red wine
  • Snack: Canned tuna fish in water over whole grain crackers

Thursday

  • Breakfast: Diced sweet potatoes sauteed in olive oil with spinach and mushrooms; 1 egg; 1 slice whole grain toast; black coffee, green tea or water
  • Lunch: Salad with romaine, tomatoes, cucumbers, olives, olive oil and balsamic vinegar, topped with grilled chicken breast; water
  • Dinner: Pasta primavera topped with grilled shrimp; whole grain bread dipped in olive oil; water or one 5 oz (150 ml) glass of red wine
  • Snack: Small handful of olives

Friday

  • Breakfast: Smoothie made with plain Greek yogurt or kefir, almond butter, blueberries, spinach, and water or ice to achieve desired thickness; black coffee, green tea or water
  • Lunch: Salmon pita sandwich; raspberries; water
  • Dinner: Grilled lamb chops with mint; water or one 5 oz (150 ml) glass of red wine
  • Snack: Carrots dipped in hummus

Saturday

  • Breakfast: Mediterranean egg cups; black coffee, green tea or water
  • Lunch: Almond butter sandwich on whole grain bread with smashed strawberries and chia seeds; carrot sticks; water
  • Dinner: Tuna Nicoise salad (greens with seared tuna steak, green beans, boiled potatoes, olives, tomatoes, and an olive oil/mustard dressing); water or one 5 oz (150 ml) glass of red wine
  • Snack: 1/2 medium avocado

Sunday

  • Breakfast: Crepes with honey, orange and ricotta; black coffee, green tea or water
  • Lunch: Grilled chicken breast over brown rice with sauteed peppers and onions; water
  • Dinner: Feta and quinoa stuffed peppers; water or one 5 oz (150 ml) glass of red wine
  • Snack: 1 handful of cherry tomatoes and a small handful of olives

Should You Try the Mediterranean Diet?

The Mediterranean diet is a proven healthy way of eating.

It promotes liberal consumption of fruits, vegetables, whole grains, olive oil, nuts, seeds, and fish.

Poultry, eggs and fermented dairy can be enjoyed moderately. One or two glasses of red wine is permitted daily with meals.

This combination of foods makes the diet naturally rich in antioxidants, polyphenol, and unsaturated fats.

Studies have found the combination of these nutrients to be especially powerful. This is partly why the diet may offer so many positive health outcomes.

Specifically, the diet has been linked with lower risk of cognitive decline, digestive and bladder cancers, and metabolic syndrome.

Studies also suggest that it may lower risk for breast cancer and cardiovascular disease; however, stronger evidence is needed.

The diet may also promote modest and gradual weight loss in a sustainable fashion, but it may need to be modified to ensure success in some people.

Despite controversies surrounding some of the research, the Mediterranean diet is worth trying.

Fill your grocery cart with a colorful variety of fresh foods, and be sure to enjoy as many meals as you can with friends and loved ones to get the most out of the diet.

Previously published on dietvsdisease.org

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