Written by Dr. Savannah Muncy, Pharm.D on
August 29, 2022
Reading Time: 6 minutes

Medically Reviewed by our Medical Affairs Team

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

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Do you often feel tired and have trouble thinking clearly? If so, you may be experiencing brain fog.

Brain fog is a common symptom of food sensitivities and other health conditions. While the cause of brain fog can vary from person to person, there are certain foods that are known to cause this condition.

In this article, we will discuss the foods that cause brain fog and provide a list of healthy alternatives. We hope that this information will help you feel better and think more clearly.

Let’s get started.

What is brain fog, exactly?

Brain fog is a term used to describe the feeling of mental fatigue, confusion, and forgetfulness. This condition can make it difficult to concentrate, remember things, or even think clearly.

Brain fog has been linked to various health conditions, including food sensitivities, stress, anxiety, and sleep disorders. However, the exact cause of brain fog is often difficult to pinpoint.

What causes brain fog?

There are many potential causes of brain fog, but the most common culprit is usually a combination of several factors.

This can include everything from an unhealthy diet and poor sleeping habits to stress and underlying health conditions.

Let’s take a closer look at some of the most common causes of brain fog:

  • Poor diet: A diet high in processed foods, sugar, and unhealthy fats can lead to brain fog. These types of food can cause inflammation and disrupt the delicate balance of hormones in the body.
  • Food sensitivities: Many people experience brain fog as a result of food sensitivities or allergies. Common culprits include gluten, dairy, soy, and eggs.
  • Stress: Chronic stress can take a toll on your physical and mental health. It can lead to problems with concentration, memory, and focus.
  • Anxiety: Anxiety is a common cause of brain fog. This condition can make it difficult to focus and concentrate on tasks.
  • Sleep disorders: Sleep disorders like insomnia can cause brain fog. When you’re not getting enough sleep, it can be difficult to think clearly or stay focused.
  • Underlying health conditions: Brain fog can also be a symptom of underlying health conditions, such as adrenal fatigue, hypothyroidism, and Lyme disease.

What are the common brain fog symptoms?

In addition to difficulty thinking clearly, brain fog can also cause other symptoms, such as:

  • fatigue
  • headaches
  • trouble concentrating
  • challenges with decision making
  • struggles with organizing thoughts
  • memory problems
  • forgetfulness
  • confusion or disorientation

If you’re experiencing any of these brain fog symptoms, it’s essential to see a doctor to rule out any underlying health conditions.

Top Foods that Cause Brain Fog

Now that we’ve discussed some of the common symptoms and causes of brain fog, let’s take a look at the types of food that can trigger this condition.

Here are some of the top foods that cause brain fog:

Refined Carbs

Refined carbs are a type of processed carbohydrate that has been stripped of its natural nutrients. These include:

  • white bread
  • pastries
  • sugary cereals
  • white rice
  • pasta
  • sweet desserts

Refined carbs are quickly absorbed into the bloodstream, which can cause a spike in blood sugar levels. This can lead to brain fog, as well as fatigue and irritability.

What to Eat Instead

If you’re experiencing brain fog, it’s best to avoid refined carbs and opt for complex carbohydrates instead. These include whole grains, fruits, and vegetables.

More specific examples include:

  • Quinoa
  • Sweet potatoes
  • Brown rice
  • Oatmeal
  • Berries
  • Broccoli
  • Brussels sprouts

These complex carbs are rich in fiber and other nutrients that can help to improve focus and mental clarity.

Foods High in Trans Fat

Trans fat is a type of unhealthy fat found in processed meals. It’s made by adding hydrogen to vegetable oils, which makes them solid at room temperature.

Some common examples of foods high in trans fat include:

  • fried meals
  • vegetable shortening
  • stick margarine
  • hydrogenated oils
  • frozen pizza
  • microwave popcorn
  • dairy products
  • refrigerated dough, such as rolls and biscuits
  • commercial baked goods, such as pies, cakes, and cookies.

Trans fat has been linked to a number of health problems, including heart disease, high blood pressure, stroke, and diabetes. It can also cause brain fog by promoting inflammation and disrupting hormone levels.

What to Eat Instead

If you’re hoping to avoid brain fog, it’s best to steer clear of foods high in trans fat. Instead, opt for healthy, unsaturated fats, such as those found in:

  • avocados
  • olives
  • nuts and seeds
  • fatty fish
  • flaxseeds
  • chia seeds
  • extra virgin olive oil.

These healthy fats can help you lose weight, improve brain function, and protect against inflammation.

Sugary Foods

Sugary foods are another common trigger of brain fog. When you eat sugary meals, your blood sugar levels spike, which can lead to a number of problems, including:

  • fatigue
  • irritability
  • mood swings
  • difficulty concentrating
  • headaches
  • memory problems.

Popular sugary foods that most Americans eat daily include:

  • soda
  • fruit juice
  • sports drinks
  • candy
  • cookies
  • cake
  • pastries
  • sweetened dairy products,
  • any food with artificial sweeteners.

What to Eat Instead

To avoid brain fog, it’s best to limit your intake of sugary meals and opt for healthy alternatives instead. These include:

  • water
  • herbal tea
  • unsweetened coffee
  • vegetables
  • dark chocolate
  • snack bars
  • chia seeds
  • legumes
  • yogurt
  • fruits like berries, watermelon, and bananas.

These foods can help to improve your focus and mental clarity while also helping you fight sugar cravings and keep your energy levels stable.

Highly Processed Foods

Processed foods are another common trigger of brain fog. These meals are usually high in artificial sweeteners, unhealthy fats, and additives that can lead to inflammation.

Some examples of highly processed foods include:

  • fast food
  • packaged snack foods (e.g., crisps, sausage rolls, pies, and pasties)
  • processed meat (e.g., hot dogs, sausage, hams)
  • microwave meals
  • instant noodles
  • soda
  • sweetened juice products
  • sweetened breakfast cereals
  • canned soup.

Processed meals are often high in calories and low in nutrients, which can lead to weight gain and a host of other health problems. These foods can also cause brain fog by disrupting hormone levels and increasing inflammation.

What to Eat Instead

If you’re hoping to avoid brain fog, it’s best to limit your intake of processed foods and opt for whole, unprocessed meals instead. These include:

  • fruits
  • vegetables
  • legumes
  • whole grains
  • nuts and seeds
  • healthy fats
  • lean protein.

And eating foods such as artichoke, avocado, and pumpkin can help to enhance cognitive function and ward off inflammation.


Aspartame is an artificial sweetener found in many diet sodas and sugar-free ea. Although it’s much sweeter than sugar, it doesn’t contain any calories.

Despite its popularity, aspartame has been linked to a number of health problems, including brain fog. Some studies have shown that aspartame can impair memory and cognitive function.

What to Eat Instead

If you’re hoping to avoid brain fog, it’s best to limit your intake of aspartame and opt for natural alternatives instead. These include:

  • stevia
  • coconut sugar
  • honey
  • maple syrup
  • erythritol
  • xylitol
  • yacon syrup
  • monk fruit sweetener.

Not only can these natural sweeteners help improve your cognition and memory, but they can also fight sugar cravings.

Fish High in Mercury

Fish is a healthy food that’s high in protein and omega-three fatty acids. However, some fish can contain high levels of mercury.

According to the World Health Organization, high levels of mercury can produce harmful effects on the central nervous system, immune and digestive systems, kidneys, lungs, and in severe cases, death.

Studies show that these types of fish are high in dietary mercury:

  • Bigeye tuna
  • Swordfish
  • Shark
  • King mackerel
  • Gulf tilefish
  • Marlin
  • Orange roughy
  • Grouper
  • Bluefish
  • Halibut
  • Sablefish (black cod)
  • Spanish mackerel (gulf)
  • Fresh tuna (except skipjack)
  • Chilean sea bass.

Mercury is a toxic metal that can damage the central nervous system. If you eat fish high in mercury, it can lead to problems with:

  • memory
  • attention span
  • language skills
  • mood swings.

What to Eat Instead

Consumer Reports listed a guide of low to lowest-mercury fish:

Lowest-mercury fish:

  • Shrimp (wild or farmed in the U.S.)
  • Scallops
  • Sardines
  • Wild and Alaskan salmon
  • Oysters
  • Squid (domestic)
  • Tilapia

Low-mercury fish:

  • Haddock
  • Pollock
  • Flounder and sole (flatfish)
  • Atlantic croaker
  • Crawfish
  • Catfish
  • Trout
  • Atlantic mackerel
  • Crab
  • Mullet

These fish are lower in mercury and higher in omega-three fatty acids, which can help improve cognitive function. If you’re pregnant or breastfeeding, it’s important to limit your intake of fish high in mercury.


Monosodium glutamate (MSG) is a common food additive that’s used to enhance flavor. It’s found in many processed and packaged foods (e.g., hot dogs and hams), as well as restaurant meals.

MSG has been linked to a number of health problems, including brain fog. Some studies have shown that MSG can impair memory and cognitive function.

What to Eat Instead

If you’re hoping to avoid brain fog, it’s best to limit your intake of MSG and opt for natural alternatives instead. These include:

  • salt
  • pepper
  • garlic powder
  • onion powder
  • cumin
  • chili powder
  • paprika
  • cayenne pepper
  • ginger
  • cilantro
  • lemon juice
  • vinegar.

These spices can enhance the flavor of your food without the negative side effects of MSG.

Final Thoughts

If you’re struggling with brain fog, it might be time to take a closer look at what you eat and start transitioning to a healthy diet.

Processed foods, artificial sweeteners, and certain types of fish can all contribute to cognitive problems.

Instead, opt for whole, unprocessed foods like fruits, vegetables, and lean protein. And be sure to include natural sweeteners and spices to enhance the flavor of your food.

If you want to learn more about clearing brain fog effectively and improving your overall brain health, check out these educational resources on our blog.

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