Written by Dr. Savannah Muncy, Pharm.D on:

If you’re feeling foggy, unfocused, and all-around icky, you might be dealing with brain fog. This frustrating condition can make it difficult to concentrate and get things done.

While there is no one magic cure for brain fog, avoiding certain foods can help.

In this article, we’ll discuss the ten brain fog foods to avoid and provide tips on how to eat smarter.

Let’s get started!

What is brain fog, exactly?

Brain fog is a term used to describe feelings of fuzzy thinking, mental fatigue, and brain drain. It can make it hard to focus, remember things, or even think clearly.

This mild cognitive impairment often lasts for a few days to a couple of weeks, but it could also develop into a cognitive dysfunction that lingers for a few weeks to a few months, depending on the severity of the cause of brain fog.

Take note that brain fog itself is not a medical condition, but it is usually a symptom of an underlying health issue, a medical condition, or the result of certain life choices.


The common causes of brain fog often include:

  • Dehydration
  • Lack of sleep
  • Sleep disorders
  • Poor diet
  • Nutritional deficiencies
  • Anxiety
  • Depression
  • Chronic stress
  • Hormonal imbalances (especially during menopause)
  • Medications and treatments
  • Certain medical conditions like multiple sclerosis, chronic fatigue syndrome, and fibromyalgia.


The symptoms of brain fog can vary from person to person, but the most common ones include:

  • Fatigue
  • Trouble concentrating or focusing
  • Poor memory recall
  • Difficulty completing tasks
  • Disorganization
  • Confusion
  • Irritability
  • Low mood
  • Struggles with decision-making
  • Difficulty in problem-solving
  • Trouble finding the right words in conversations

While brain fog can be caused by a variety of factors—from sleep deprivation to underlying medical conditions—what you eat plays a significant role in how you feel and how your brain functions.

Certain foods can cause inflammation, mess with your hormones, and contribute to symptoms of brain fog.

Other foods, on the other hand, are packed with nutrients that support brain health and help you feel more alert and focused.

To help you make the best choices for your brain, we’ve put together a list of the worst foods for your brain.

Top Nine Brain Fog Foods to Avoid

If you’re wondering what foods cause brain fog, look no further. Here are the top nine types of food that cause brain fog:

1) Added Sugars

Added sugars are one of the worst foods you can eat. That’s because they cause inflammation and mess with your hormones.

Research reveals that added sugars can lead to blood sugar spikes and crashes that leave you feeling exhausted and make it hard to concentrate.

To cut back on added sugars, avoid:

  • sugary drinks like soda, fruit juices, and sports drinks,
  • high fructose corn syrup,
  • processed foods, desserts, and other sweets.

Instead, opt for whole foods like:

  • fruits,
  • vegetables,
  • and unprocessed grains.

These foods will give you lasting energy and help keep your blood glucose levels stable.

2) Refined Carbs

Refined carbs are another brain fog food to avoid. That’s because they’re quickly digested and cause blood sugar spikes and crashes.

Moreover, refined carbs are often high in added sugars that can further contribute to brain fog and harm your blood vessels in the long run.

Studies also show that a high intake of refined carbs is linked to a higher risk of brain disorders like Alzheimer’s disease.

To avoid refined carbs, stay away from:

  • white bread,
  • pastries,
  • white rice,
  • and other processed foods made with bleached flour.

Instead, choose whole-grain alternatives like:

  • whole-wheat bread,
  • brown rice,
  • and quinoa.

These foods are packed with brain-boosting benefits from nutrients like fiber, vitamin E, and omega-three fatty acids.

Plus, they’re low on the glycemic index, meaning they won’t cause blood glucose spikes and crashes.

Make sure you also avoid hidden sources of refined carbs like:

  • pasta sauce,
  • cereals,
  • and granola bars.

Instead, opt for whole foods like:

  • fruits,
  • vegetables,
  • nuts,
  • and seeds.

These brain-healthy foods will give you sustained energy throughout the day.

You can also try swapping out refined carbs for healthier alternatives like:

  • cauliflower rice
  • or zucchini noodles.

Just be sure to avoid processed versions of these foods that often contain added sugars and other unhealthy ingredients.

3) Foods High in Trans Fat

Trans fat is a type of unhealthy, man-made fat that’s found in processed foods. Studies reveal that eating trans fat can lead to brain fog and other cognitive problems.

Trans fat can also harm your brain cell membranes and this increases your risk of developing Alzheimer’s disease and other neurological disorders.

To avoid trans fat, stay away from:

  • processed foods,
  • fast food,
  • and margarine.

Instead, choose healthy fats like:

  • olive oil,
  • avocados,
  • and nuts.

These brain-healthy fats will help improve your cognitive function and protect your brain from damage.

So, always make sure you also check food labels for trans fat.

If a product contains “partially hydrogenated oils,” it likely contains trans fat. Avoid these products and opt for brain-healthy alternatives instead.

4) Highly Processed Foods

These foods are the leading cause of brain fog. That’s because they’re usually high in sugar, saturated fat, and refined carbs.

Additionally, processed foods contain few brain-boosting nutrients like fiber and omega-three fatty acids.

Studies show that a diet high in processed foods is linked to an increased risk of cognitive decline, mood disorders, and brain disorders like Alzheimer’s disease and dementia.

To avoid processed foods, stay away from:

  • fast food,
  • pre-packaged meals,
  • processed meats,
  • Cookies and cakes,
  • Candies
  • Reconstituted meat products (e.g., hot dogs)
  • Sweetened juice products
  • White flour, pasta, and bread.

Instead, choose healthy whole foods like:

  • fruits,
  • vegetables,
  • nuts,
  • seeds,
  • whole grains,
  • lean meats,
  • fish,
  • eggs,
  • beans,
  • legumes.

These brain-healthy foods will help improve your cognitive function and protect your brain from damage.

So, make sure you always check food labels to see how processed a product is.

If a product contains lots of artificial ingredients, it’s likely highly processed. Avoid these products and opt for brain-healthy alternatives instead.

5) Aspartame

Aspartame is an artificial sweetener found in many diet sodas and sugar-free foods.

While it’s often touted as a healthy alternative to sugar, studies show that aspartame can actually cause brain fog.

According to a study published in Nutritional Neuroscience in 2017, aspartame has been linked to learning disorders, migraines, irritable moods, anxiety, depression, and sleeplessness.

That’s because aspartame breaks down into methanol in the body, which can then be converted into formaldehyde.

Formaldehyde is a neurotoxin that can damage the brain and nervous system.

So, if you’re looking to improve your cognitive function, it’s best to avoid aspartame-containing products, such as:

  • sugarless candy
  • zero sugar soda or diet soda
  • sugar-free salad dressing
  • sugar-free ice cream
  • no sugar energy bars
  • reduced-calorie fruit juice
  • light yogurt
  • sugar-free gum
  • reduced sugar ketchup

Instead, opt for brain-healthy alternatives like:

  • stevia
  • monk fruit extract
  • honey
  • dates
  • coconut sugar
  • maple syrup
  • molasses
  • agave nectar

These natural sweeteners won’t cause brain fog or other cognitive problems.

So, make sure you always check food labels to see if a product contains aspartame. If it does, avoid the product and opt for a brain-healthy alternative instead.

6) Fish High in Mercury

Mercury is a toxic heavy metal that can damage the brain and nervous system.

Research shows that higher blood mercury levels were linked to poorer performance on a memory test that assessed the ability to recall a complex, two-dimensional line drawing.

Unfortunately, many fish contain high levels of mercury.

To avoid fish high in mercury, stay away from consuming:

  • Shark
  • Swordfish
  • King mackerel
  • Tilefish
  • Orange roughy
  • Marlin
  • Tuna (fresh or canned)
  • Sea bass
  • Barramundi
  • Snapper
  • Grouper
  • Halibut.

Instead, choose fatty fish that are lower in mercury, such as:

  • Anchovies
  • Butterfish
  • Catfish
  • Canned light tuna*
  • Cod
  • Crab
  • Croaker (white)
  • Haddock
  • Herring
  • Pollock
  • Salmon
  • Sardines.

*Canned albacore tuna generally contains more mercury than canned light tuna. When buying canned tuna, look for “light” or “skipjack,” which are lower in mercury than “white” or “albacore.”

7) Fried Foods

Fried foods are often high in unhealthy trans fats, which can damage the brain.

Studies show that trans fats can cause memory problems and may lead to an increased risk of Alzheimer’s disease and other forms of dementia.

What’s more, fried foods contain acrylamide, a carcinogen that has been linked to brain tumors.

So, it’s best to avoid fried foods, such as:

  • French fries
  • Potato chips
  • Doughnuts
  • Fried chicken
  • Fried fish.

Instead, opt for brain-healthy alternatives, such as:

  • baked potato chips
  • air-popped popcorn
  • baked chicken fingers
  • grilled fish.

These alternatives are lower in saturated fat and chemicals that can damage the brain.

8) High-Glycemic-Load Carbohydrates

High-glycemic-load carbohydrates are foods that cause a rapid spike in blood sugar levels.

Studies show that eating high-glycemic-load carbohydrates can impair cognition by damaging the brain cells, and it can lead to higher risks of nutritional deficiencies.

Moreover, having high blood glucose levels or type 2 diabetes has been linked to an increased risk of Alzheimer’s disease and other forms of dementia.

So, it’s best to avoid high-glycemic-load carbohydrates, such as:

  • white bread
  • white rice
  • pasta
  • cereal
  • potatoes
  • cornflakes.

Instead, opt for brain-healthy alternatives, such as:

  • whole wheat bread
  • brown rice
  • quinoa
  • oatmeal
  • sweet potatoes.

These alternatives are lower on the glycemic index, which means they won’t cause a rapid spike in blood sugar levels.

9) Nitrates and Nitrites

Nitrates and nitrites are food additives that have been linked to brain fog and other cognitive problems.

Studies show that these additives can alter brain function and lead to an increased risk of dementia.

So, it’s best to avoid foods that contain nitrates or nitrites, such as:

  • cured meats
  • hot dogs
  • bacon
  • sausage
  • deli meats.

Instead, opt for brain-healthy alternatives, such as:

  • uncured meats
  • vegetarian protein sources.

These alternatives are lower in harmful additives that can damage the brain.

The Bottom Line

Avoiding brain fog-inducing foods is a great way to keep your mind sharp and your cognitive function in top form.

By making some simple changes to your diet, you can help protect your brain health and reduce your risk of developing dementia or other cognitive problems.

When it comes to brain health, what you eat matters, so make sure to choose the right foods for your brain that will help you stay sharp and focused all day long.

If you’re looking for more tips on how to improve your brain health, make sure to check out our blog. We have tons of great articles and resources that can help you boost your brain power.

And, if you’re looking for a great community to connect with others who are interested in brain health, feel free to join our online community.

It’s a great place to ask questions, share tips, and connect with others interested in staying sharp and keeping their brains healthy.

We hope you found this article helpful. If so, please share it with your friends and family to help spread the word about the importance of a healthy brain. And check back often for more great articles and resources about brain health and wellness. 

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