What Science Tells Us About the Best Diet for Brain Health

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What Science Tells Us About the Best Diet for Brain Health

Your Diet Can Help You To Beat Brain Fog, Improve Mood, and Fight Cognitive Decline

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Your brain is vulnerable to poor diet and lifestyle choices. Chronic inflammation and poor blood sugar control are significant risk factors for the development of Alzheimer’s disease [1, 2]. Better dietary choices are your key to unlocking better brain health.

What’s the best diet for brain health? Research into this topic is still preliminary and suggests a few different approaches. However, eating to control inflammation and manage blood sugar is most important.

Brain fog, depression, and/or anxiety are signs that all is not well with your brain health. Taking steps now to improve your diet and lifestyle can prevent worse outcomes as you age.

In this article, we’ll take a deep dive into the research on brain health and steps you can take to improve it.

Best diet for brain health: A variety of fruits and vegetables

Inflammation and Brain Health

Just like the rest of your body, your brain can become inflamed. Brain inflammation has been linked to depression, brain fog, mild cognitive impairment, and even the risk of dementia.

What’s more, we’re learning that the inflammation behind poor brain health can lead to low motivation and poor decision making, which set the stage for unhealthy habits.

This means that eating too much fast food, staying up late, and not exercising can become a self-perpetuating cycle of bad habits. A number of studies have shown that sleep deprivation significantly increases appetite, calorie consumption, and can lead to poor food choices [3, 4, 5].

The empowering news is that when you take steps to improve your diet and reduce inflammation, your brain benefits and so does your motivation. While research hasn’t yet definitively shown the best diet for brain health, it does provide dietary direction and other steps you can take to optimize your brainpower now and as you age.

The Gut-Brain Connection

Best diet for brain health: Illustration of 
Gut-Brain connection

The gut and brain communicate directly with each other through biochemical signals sent along the vagus nerve [6]. Neurotransmitters (dopamine, serotonin, and norepinephrine) are manufactured in the gut and transported to the brain along the vagus nerve, affecting appetite control, pain sensations, mood, memory, and much more [7].

This brain-gut communication system also works in the opposite direction as the brain regulates digestion and motility, the cleansing waves of muscle contractions that move waste through your digestive tract.

Imbalances in the gut microbiome (the complex community of microorganisms that live in your intestines) can alter brain function [8, 9], produce inflammation, and dysregulate gut-brain communication. This suggests that it may be possible to achieve better brain health through diet and gut-directed therapies. Let’s explore the research on the best diet for brain health.

Diet and Mood Disorders

Significant evidence connects depression and anxiety with an unhealthy gut. For example:

  • IBS (irritable bowel syndrome) patients are three times as likely as healthy subjects to have anxiety or depression [10].
  • Patients with inflammatory bowel disease (Crohn’s disease and ulcerative colitis) have similar rates of anxiety and depression. However, their symptoms are generally less severe compared with IBS patients [11].
  • In a large study of patients with suspected non-celiac gluten sensitivity, 39% reported anxiety [12].

Two large studies have analyzed available research on the effects of dietary interventions on mild depression and anxiety [13, 14]. Both studies concluded that dietary changes were more likely to help depression (the majority of studies evaluated mild depression only) and less likely to help anxiety. Female participants experienced greater positive impacts on both depression and anxiety from dietary interventions [15]. Most of the diets reduced high-fat, high-sugar, low-nutrient foods, and replaced them with high-fiber, nutrient-dense foods like whole grains and veggies. The effective diets were less likely to recommend low-cholesterol choices or replacing red meat with leaner meats [16].

A 2018 meta-analysis looked at the impacts of gluten-free diets on symptoms of depression. This study found that a long-term gluten-free diet may significantly reduce and even normalize depression in subjects with celiac disease, IBS and non-celiac gluten sensitivity [17]. This effect is not seen in subjects without these conditions.

In a systematic review that looked more specifically at the available data for anxiety, 56% of subjects experienced improved anxiety with the use of probiotics and a low FODMAP diet [18].

Another study looked at the impact of a low FODMAP diet on the mood of IBS patients [19]. This study found significant improvements in anxiety, depression, happiness and overall vitality.

The low FODMAP diet is an established treatment for IBS patients [20, 21] and works by restricting fermentable carbohydrates that feed bacterial overgrowth in the gut. The low FODMAP diet restricts whole grains and some fruits and vegetables that are encouraged in other diets.

This is an important result, as the low FODMAP diet is very different from standard healthy diet recommendations that don’t seem to work for anxiety.

Diet and Cognitive Function

The most well-studied diet for cognitive function is the Mediterranean diet, a diet rich in whole foods, fresh fruit and vegetables, oily fish like sardines, and healthy fats like olive oil.

Overall, the research suggests that the Mediterranean diet is helpful. However, the results aren’t fully conclusive:

  • A 2016 review of 32 studies associated the Mediterranean diet with improved cognitive function, a decreased risk of cognitive impairment, and decreased risk of dementia [22]. However, results were not consistent and some of the studies reviewed found no association between diet and improved cognitive function.
  • A 2018 systematic review found that a Mediterranean diet improved only 12.1% of outcomes on cognitive tests [23]. Overall, the researchers found the evidence to be inconclusive but noted that the largest, highest-quality clinical trial showed significant cognitive improvements.

Additional research suggests that a variety of dietary approaches can benefit cognitive health:

  • A 2019 meta-analysis found that a variety of high-quality diets made small, positive impacts on cognitive function in healthy adults [24].
  • A 2018 systematic review examined diet and cognitive health in older adults [25]. Overall, a number of different dietary approaches showed positive effects on cognitive function. These include the Mediterranean diet (with most evidence available), the DASH diet (Dietary Approach to Stop Hypertension), the MIND diet (a Mediterranean-DASH diet hybrid), and other anti-inflammatory diets.

Finally, additional evidence suggests that calorie restriction may also be helpful for cognitive function:

  • In a study of normal elderly subjects, calorie consumption was reduced by 30% in one group of subjects. After three months, this group significantly improved performance on memory tests compared to two different control diet groups [26].

What About Brain Fog?

Brain fog is a common symptom characterized by slowed thinking, forgetfulness, inability to focus, and poor mental stamina [27]. Brain fog is seen in patients with Crohn’s disease, fibromyalgia, celiac disease, and many other chronic conditions. It’s thought to be caused by inflammation in the brain.

Medically, brain fog may be referred to as subclinical cognitive impairment [28]. Despite being a very common symptom, there is not much research on the subject. One study has shown that brain fog resolved in untreated celiac patients after 12 months on a gluten-free diet [29].

While I prefer to use research data over clinical observation, in this case, it’s worth mentioning that brain fog typically clears up in my patients once they improve their gut health.

Diet and Alzheimer’s Disease

Best diet for brain health: Illustration of Alzheimer' Disease progression

Nicknamed “type 3 diabetes,” Alzheimer’s disease can develop when brain cells become insulin resistant and can no longer use glucose properly [30].

Alzheimer’s disease is a progressive disease that causes memory loss and is the most common type of dementia. Chronic inflammation caused by poor metabolic health contributes significantly to the development of Alzheimer’s.

Diet Is Critical for Preventing Alzheimer’s

The biological and neurological changes that lead to Alzheimer’s seem to be initiated decades in advance of the development of the disease [31].

A Swedish study that followed 1152 patients for 40 years found that men and women who were overweight in midlife were more likely to develop dementia [32]. A similar study followed patients for seven years and found that, even without diabetes, patients with higher blood sugar levels were more likely to develop dementia [33]:

  • Patients with an average fasting blood sugar of 115 mg/dL were 18% more likely to develop dementia than those with a fasting blood sugar of 100 mg/dL.
  • Patients with blood sugar levels of 190 mg/dL were 40% more likely to develop dementia when compared to patients with blood sugar levels of 160 mg/dL.

Research also suggests that people with metabolic syndrome (a combination of high blood pressure, high blood sugar, excess fat around the waist, and abnormal cholesterol levels) are at increased risk of Alzheimer’s [34].

Managing weight and metabolic health through midlife is one of the most important steps you can take to avoid memory loss as you age. A healthy diet and lifestyle are critical for preventing Alzheimer’s disease.

Does Diet Help Alzheimer’s Patients?

While there is no cure for Alzheimer’s disease, research suggests that dietary interventions may be somewhat helpful for Alzheimer’s patients.

  • A 2020 systematic review evaluated the effect of ketogenic interventions (extreme carbohydrate restriction) on patients with Alzheimer’s disease or mild cognitive impairment [35]. Ketogenic interventions were generally effective in improving general cognition and episodic memory (memory of past experiences) and secondary memory (long-term storage and recall of information).
  • Another systematic review published in 2020 looked at dietary interventions for Alzheimer’s patients more broadly. The researchers concluded that the effects of most dietary interventions are inconclusive and better research is needed [36]. However, omega-3 fatty acids, probiotics, ginseng, inositol, and specialized nutritional formulas appeared to have positive effects on cognition in Alzheimer’s disease.

Diet and Brain Injury

An emerging topic for research is the use of dietary interventions to control the inflammation associated with traumatic brain injury and to improve recovery [37].

Although there is not yet a lot of direct research available, one brain injury patient has done remarkable work in synthesizing available research about inflammation, diet, and brain health in order to develop new options for brain-injured patients. Calvin Balaster also provides an inspirational story of recovery from severe brain injury.

Calvin’s work makes it apparent that we still have much to learn about the best diet for brain health.

Probiotics and Brain Health

Different words forming the shape of a brain

A healthier diet should be your first step towards improving gut health and lowering inflammation. Your next best step for better gut health is taking high-quality probiotic supplements.

A 2018 systematic review that examined the relationship between brain function and the gut-brain axis concluded that gut dysbiosis alters brain function and suggested that probiotics have the potential to treat psychiatric and or neurological conditions.

Let’s look at what we know so far about probiotics and brain health.

Probiotics and Cognitive Function

Recent research suggests that probiotics can be helpful for patients with mild to severe cognitive issues:

  • A clinical trial in South Korea examined probiotic supplementation in 100 people with mild cognitive impairment [38]. Half of the participants were given probiotic capsules and half were given a placebo. At the end of 12 weeks, the probiotic group had improved cognitive performance, particularly in terms of attention.
  • A clinical trial in Tokyo prescribed probiotics or placebo to 117 older adults with memory complaints [39]. After 12 weeks, participants in the probiotics group who initially scored low on cognitive function tests saw improvements in tests of immediate and delayed memory (the best measurement for identifying the earliest stage of dementia).

However, for healthy patients, probiotics appear to have no effect on cognitive function [40]. Basically, if your gut is already healthy, don’t expect probiotics to improve your brainpower.

Probiotics and Alzheimer’s Disease

Two clinical trials showed that 12 weeks of probiotic supplementation can improve cognitive function and some metabolic profiles for Alzheimer’s patients [41, 42].

Probiotics and Mood

We’ve already shown a strong association between mood disorders and gut conditions. So, it’s not surprising that research shows probiotics are helpful for depression:

  • A meta-analysis found that treating the gut with probiotics can result in significant improvements in the mood of individuals with mild to moderate depressive symptoms [43]. This effect was not seen in healthy individuals.
  • Another systematic review with meta-analysis of clinical trials has found probiotic supplements significantly reduce depression [44].
  • One clinical trial found probiotics to be effective for patients suffering from major depressive disorder [45].

Research also shows that anxiety may be improved with probiotics. The data here are not as strong, but there is a documented anti-anxiety effect in some human clinical trials [4647, 48, 49]. However, in four meta-analyses of available research, all of the researchers agree that while there may be some anti-anxiety effect from probiotics, current data is insufficient [50, 51, 52, 53].

The Best Diet for Brain Health

The available research into diet and brain health aligns well with my standard dietary advice for good gut health. Since we know there’s a gut-brain connection, this makes sense.

Four Principles of a Healthy Diet infographic

Here are four important principles when it comes to healthy eating:

  1. Eat to control inflammation.
  2. Eat to control and balance blood sugar.
  3. Find your ideal intake of carbohydrates and prebiotics.
  4. Identify your food allergies and intolerances (this will help control inflammation).

Keeping these guidelines in mind, what’s the best diet for better brain health? Let’s look at some options.

Mediterranean Diet

Much of the research has focused on the Mediterranean diet and shows it is a good choice for brain health. The Mediterranean diet is anti-inflammatory and can help to control and balance blood sugar, so it covers our first and second principles of healthy eating.

If you are currently eating a standard American diet, with lots of processed foods, sugars, and trans fats, the Mediterranean diet is an excellent choice.

Paleo Diet

The paleo diet has not been included in much of the research on brain health. However, it shares many similarities with the Mediterranean diet. It is anti-inflammatory [54, 55] and focuses on whole, healthy foods.

The paleo diet is lower in carbs than the Mediterranean diet since it eliminates grains such as brown rice, beans, legumes, and lentils. This makes it even more effective for helping you to stay off the blood sugar roller coaster [56, 57].

The paleo diet also restricts gluten and dairy, which are some of the most common food intolerances. Following the paleo diet for a few weeks and then reintroducing gluten or dairy is a good way to identify your tolerance for these foods.

Choose the paleo diet if you already follow standard guidelines for a healthy diet and want to address the third principle of a healthy diet by experimenting with a reduced carbohydrate diet.

The paleo diet doesn’t usually emphasize fatty fish (like sardines and mackerel) in the same way as the Mediterranean diet. However, it’s a good idea to incorporate plenty of fish into your Paleo diet.


The low FODMAP diet takes another step in reducing the specific types of carbohydrates that feed bacteria overgrowths. This diet is much more restricted and is tailored for patients with chronic gut conditions like IBS, IBD, and SIBO.

The low FODMAP diet restricts most grains, beans, and dairy, like the paleo diet. It also restricts some types of fruits and vegetables but allows certain foods in those categories like flaxseed, chia, leafy greens, and leafy vegetables.

More Tips for Brain Health

In addition to a better diet and probiotics, research suggests other strategies for improving brain health:

  • Research shows that regular aerobic exercise improves cognitive performance [58, 59].
  • Getting enough sleep is very important for gut health, managing inflammation, and better cognitive function [60, 61, 62, 63].
  • Healthy sun exposure and adequate vitamin D levels can also boost brain health.

A Better Brain and Better Overall Health

What’s the best diet for brain health?

There’s no one best diet and what matters most is a long-term commitment to healthy eating. Standard medical advice leans towards the Mediterranean diet. However, there are many good dietary options.

Like so many other health conditions, cognitive decline begins in the gut. Once you start to improve your gut health, you’ll discover health benefits for your brain, your heart health, your hormonal health, and so much more.

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