By Dr. Mercola

The Mediterranean diet emphasizes fresh vegetables, nuts, and healthy fats, particularly olive oil, while downplaying processed foods.

This combination is undoubtedly part of its many health benefits, which includes the reversal of metabolic syndrome, improving body composition, and normalizing your blood pressure and cholesterol levels.

Extra virgin olive oil is clearly one of the "good fats” that should be included in your diet. Just keep in mind that it should not be used to cook with, as it is highly susceptible to oxidative damage when heated. Instead, it should be added cold to salads and other dishes.

Olive oil is a monounsaturated fat whose health benefits stem from it being unrefined and unheated. It also contains vitamin E and A, chlorophyll, magnesium, squalene, and a host of other cardio-protective nutrients.

In addition, it doesn’t upset the critical omega 6:3 ratio, as most of the fatty acids in olive oil are actually omega-9.

Studies have shown that extra virgin olive oil can reduce some cancers, reduce LDL cholesterol levels, and improve rheumatoid arthritis; the same or similar benefits touted by the Mediterranean diet.

Recent research also suggests a Mediterranean-style diet rich in nuts and olive oil can help boost memory and cognition in older adults.^1,2

Mediterranean Diet May Boost Memory and Cognition

Previous research has 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 researchers³ 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:

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

As reported by Reuters:⁴

“Based on the brain function tests done before and after the study, the group eating low-fat foods had a significant decrease in memory and cognitive function.

The group following a Mediterranean diet with supplemental nuts had significant improvements in memory, while the group adding extra virgin olive oil experienced significantly better cognitive function.”

Your Brain and Body Need Healthy Fats 

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.

Other diets shown to be particularly beneficial for brain health include the DASH and the MIND diets,⁵ 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. Unfortunately, all of them generally recommend limiting saturated fats, such as those found in red meats and eggs.

Saturated fats, however, have been falsely vilified for the epidemics of heart disease and obesity. In reality, animal fats promote optimal health. Omega-3 fat is also crucial for optimal brain function, but it’s important to be careful when choosing your sources.

Very few fish are low in mercury while being high in healthy fat, so just eating more fish may be counterproductive, as mercury, PCBs, and other contaminants surely will not do your health any favors.

Good choices include smaller fatty fish like sardines and anchovies, and wild-caught Alaskan salmon. Another option to make sure you’re getting enough omega-3 is to take a high-quality supplement such as krill oil.

The Importance of Omega-3 Fat for Psychological Health

Speaking of omega-3, recent research⁶ found that omega-3 supplementation helped improve attention-deficit/hyperactivity disorder (ADHD) symptoms and cognitive control in children.

Crazy enough, the omega-3 was given in the form of EPA- and DHA-enriched margarine, which is some of the worst fat you could possibly eat. It would be interesting to see how much better these children might have fared had they not counteracted the beneficial effects of the omega-3 with a processed trans fat...

Here, those who received the EPA/DHA-enriched margarine experienced no benefit in terms of cognitive control, but I would argue that the results may have been adversely affected because of the margarine.

Other recent research^7,8,9 suggests animal-based omega-3 in combination with vitamin D can improve cognitive function and behavior associated with certain psychiatric conditions—including ADHD, bipolar disorder, and schizophrenia—by regulating your brain’s serotonin levels.

The omega-3 fatty acid EPA reduces inflammatory signaling molecules in your brain that inhibit serotonin release from presynaptic neurons, thereby boosting your serotonin levels. DHA also has a beneficial influence on serotonin receptors, by increasing their access to serotonin.

Deemphasize Whole Grains for Optimal Brain Health

Another potential pitfall of these diets is their emphasis on whole grains. Along with processed vegetable oils and sugars, excessive grain consumption—even if they’re organic whole grains—contributes to disease and obesity for the simple fact that your body still converts them to sugar.

As noted by neurologist Dr. David Perlmutter, author of the book, Grain Brain, gluten sensitivity appears to be involved in most chronic disease, including Alzheimer’s, and non-vegetable carbohydrates can have a powerfully toxic effect on your brain.

According to Dr. Perlmutter:

"This ‘whole grain goodness,’ as the US Department of Agriculture is trying to convince us we should focus on in terms of our dietary choices, is the cornerstone of our most devastating diseases... Alzheimer's, cardiovascular disease, and obviously, diabetes... It’s the getting away from fat and the substitution with wheat- and corn-based carbohydrate (high-fructose corn syrup) that really, in my opinion, explains this huge explosion of degenerative conditions that are crippling us...

But the quality of the fat we consume is absolutely fundamental. When we're saying high-fat diet, we're not talking about prepared foods on the Twinkie aisle at the grocery store that contain modified trans fats. Hydrogenated fats that are clearly coffin nails. They're a great risk for brain disorders, heart disorders, diabetes, etc. We're talking about these beautiful, natural fats that we have been consuming for more than two million years."

Dr. Perlmutter also cites research from the Mayo Clinic, published in the Journal of Alzheimer's Disease showing that diets rich in carbohydrates are associated with an 89 percent increased risk for dementia, while high-fat diets are associated with a 44 percent reduced risk.

Examples of beneficial fats that your body—and your brain in particular—needs for optimal function include organic grass-fed raw butter, clarified butter called ghee, olives, organic virgin olive oil, and coconut oil, nuts like pecans and macadamia, free-range eggs, wild Alaskan salmon, and avocado.

With regards to nuts, one recent study¹⁰ found that daily nut consumption translated into an extra two years of longevity, and cut death rates of cancer, heart disease, and respiratory disease. As reported by Nutrition Facts, “nut consumers lived significantly longer whether they were older or younger, fat or skinny, whether they exercised more, smoked, drank, or ate other foods that may affect mortality.” They also busted the myth that nuts’ high fat content will make you gain weight.

Link Between Diet and Memory Confirmed

In related news, another study^11,12,13 published in the journal Neurology looking at the correlation between diet and memory loss found that eating a “healthy balanced diet” appears to reduce your risk of cognitive decline. As reported by CNN:¹⁴

“Unlike previous findings relating specific diets to improvements in cognitive function, this new study suggests that improving overall diet quality is an important factor for lowering the risk of memory and thinking loss. Researchers defined a ‘healthy diet’ as one containing lots of fruits and vegetables, nuts, fish, moderate alcohol use, and minimal red meat.”

The study, which ran for nearly five years, involved nearly 28,000 people from 40 different countries. Rather than focusing on any specific set of diets, the researchers analyzed the risk for cognitive decline among those who consumed “what most organizations would consider a healthy diet,” lead author Dr. Andrew Smyth said.

“Accounting for regional differences (but not country-specific variation), participants in the study were asked about the overall servings they consumed of different types of foods in both the healthy and unhealthy categories for which they received a corresponding point score,” CNN reports.¹⁵

“‘For example, if participants consumed the standard dietary recommendations for fruits and vegetables per day, they would get a high score in that category. The reverse happens for unhealthy food choices,’ said Smyth.”

Cognitive tests were administered at the outset of the study, and again after two and five years. Overall, those scoring highest in terms of following “healthy diet” recommendations were 24 percent less likely to experience cognitive decline, compared to those with the least healthy eating habits. Overall, healthy eaters were also more active, smoked less, and had lower body mass index (BMI).

Protect Your Brain with Wise Lifestyle Choices

A number of simple lifestyle strategies can help optimize your brain health. This includes exercise, especially high-intensity interval training, calorie restriction (intermittent fasting appears to have many of the same benefits while being easier to comply with), and reducing non-vegetable carbohydrate (especially grains and sugars). According to Dr. Perlmutter, a low-carb diet high in healthy fats is a key component of Alzheimer’s prevention. Gluten appears to be particularly problematic for brain health.

You also need plenty of high-quality omega-3 fats. I prefer krill oil to fish oil, as krill oil also contains astaxanthin, which is particularly beneficial for your brain. Astaxanthin is a carotenoid that’s very good for reducing free radical-mediated damage to fat—and your brain is 60 or 70 percent fat. Two other nutrients that play important roles in your brain health are vitamin D and choline.

Researchers have located metabolic pathways for vitamin D in the brain’s hippocampus and cerebellum; areas that are involved in planning, information processing, and memory formation. In older adults, research has shown that low vitamin D levels are associated with poorer brain function.

Choline also reduces inflammation and plays a role in nerve communication. Eggs and meat are two of the best dietary sources of choline. If you do not consume animal foods, you may be at risk of a deficiency and want to consider supplementation. The state of your gut is another important consideration that can have a significant influence on your brain function. Your gut is quite literally your "second brain."

Just as you have neurons in your brain, you also have neurons in your gut, and gut bacteria transmit information from your GI tract to your brain via your vagus nerve. Abnormal gut flora has been associated with abnormal brain development, and may be an overlooked culprit in many cases of depression. In addition to avoiding sugar, one of the best ways to support gut health is to consume fermented vegetables, which are loaded with beneficial bacteria.

Last but not least, it is crucial to fully appreciate the importance of sleep. The latest sleep guidelines, based on 300 studies looking at the health effects of sleep, confirm that most adults need right around eight hours of sleep for optimal health.

It’s particularly important for brain health, because the only time your brain can detoxify is during deep sleep, which is why poor sleepers are more prone to developing neurological disorders such as Alzheimer’s. So truly, if you want your brain to function optimally, be sure to address any sleep problems you may have.