Written by Brittni Bresee on
July 6, 2021
Reading Time: 8 minutes

Medically Reviewed by our Medical Affairs Team

Written by Brittni Bresee on:

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What foods cause brain fog?

This is a question that I often get in my practice. It can be frustrating when you start to feel tired, foggy and like your memory isn’t as good. You want to know what you’re doing wrong or how to fix it. The answer is not about how much of any one thing you eat but also what you don’t eat.

In this post, I’m going to share some of the worst foods for your brain with you and what they do when eaten in excess. This includes things like saturated fats, refined sugars, fried oils and more.

All these things can lead to some serious consequences such as weight gain, digestive issues, inflammation and high cholesterol levels just to name a few.

What are the worst foods for your brain? What will it take to reverse memory loss and stay sharp as you age? The answer is simple, yet not what most would expect.

Let’s get into it!

What Foods Cause Brain Fog? Here are the Top 9

1. Fish High In Mercury

Mercury is a poisonous heavy metal that builds up in the tissue of fish. If there is more mercury in the human body than it can deal with, neurological damage can occur. Once mercury is ingested, it travels throughout the body, concentrating in the liver, brain and kidneys. And eventually into the blood brain barrier. In pregnant women it also concentrates in the placenta and fetus.

Mercury toxicity is very dangerous. Since mercury is difficult for the body to get rid of, it builds up. This is one of the reasons it’s considered a poison. Once a person has reached this point, the body then is unable to flush it fast enough before brain damage occurs. You can also experience brain fog in this process.

In pregnant women and young children it can contribute to cerebral palsy and other developmental delays. The effect mercury toxicity has on the body can be extreme. It disrupts communication between our central nervous system and our neurotransmitters. Our body is a magnet and communicates by our nerves and brain sending electrical signals. If you think about how certain metals stick to magnets, you can see how difficult mercury must be for our brain and body.

2. Refined Sugar

There have been many studies on how sugar impacts our emotions, increases brain fog, memory and eating habits. Our brain uses more sugar for energy than any other organ. The secret is feeding your brain good sugars from whole foods. Refined sugars are too processed for our body to recognize as helpful and in turn causes chaos in the brain.

Sugar impairs cognitive skills and in many people, self control. A single instance of elevated blood sugars can be harmful to the brain. This can result in poor memory and attention span.

Research shows these symptoms are from the inflammation that sugar causes in the brain.

Brain scans have also shown that blood sugar levels inhibit options elevated blood sugar levels inhibit a person’s ability to process emotions. It’s common for those struggling to keep their blood sugar within normal range, battling with depression and sadness.

High blood sugar levels also damage blood vessels. This has a great impact on brain health, and can bring up brain fog. We need our blood to flow freely and strong throughout our brain to maintain good brain health. Simply removing all processed sugars from your diet will help get rid of brain fog.

Eating whole fresh fruits will provide natural sugars the brain can use. Keeping fresh whole foods in your diet will satisfy your brain, helping you to avoid consuming toxic refined sugars.

Sugars to avoid:

  • High Fructose Corn Syrup
  • White Sugar
  • Inverted Sugars
  • Dextrose
  • Maltose
  • Rice Syrup
  • Carmel

A lot of foods in grocery stores these days are loaded with hidden sugar. Make sure to read labels on all food products. 

What foods cause brain fog? Here are the most common foods to look out for:

  • Salad Dressings
  • Ketchup
  • Mayonnaise
  • Pickles
  • Dried fruit with sugar added
  • Lunch Meats
  • Diet or Fat Free Labeled Foods
  • Canned Foods
  • Jarred foods
  • Sauces

3. Gluten

Gluten free diets have been a trend these last few years, but.. why? What is gluten? Is eliminating gluten better for us? Do I have a gluten intolerance? Is gluten causing my brain fog?

Gluten is a protein found in grains like wheat, spelt, barley and rye. It acts like a “glue”, giving it it’s name. It makes baked goods soft and fluffy.

Having light, white, soft and fluffy bread has been in high demand. To make bread even fluffier, scientists have engineered wheat to give it a higher amount of gluten.

Hundreds of years ago wheat was a different product than found at the grocery store today. Studies today show that the high amount of gluten is too difficult to process. This interrupts the gut-brain communication contributing to neurological symptoms and conditions. From mild symptoms like brain fog, clumsiness, headaches and hyperactivity. To more severe conditions like depression, chronic anxiety, epilepsy, bi-polar disorder and vertigo

4. Fried Foods

We all know fried foods aren’t a healthy option causing symptoms like heartburn and weight gain. But, did you know fried foods are one of the worst foods for your brain? Here’s why… A study by the Journal of Nutritional Science showed, people who ate a lot of friend foods had lower cognitive abilities.

They struggled more with memory, brain fog, concentration and learning abilities. While those who ate a plant based diet showed higher brain function. Scientist believe this is caused by inflammation in the blood vessels. This would slow down blood supply down to the brain.

People who eat too much fried or processed food generally don’t do as well on tests that measure their thinking skills. The likely cause is the inflammation these types of food can produce when eaten in excess, which can interfere with blood flow to brain and/or damage the brain itself.

Fried foods are also unhealthy because they’re high in trans fats. Trans fats without enough omega-3s can help fry your brain cells and inflammation can interfere with blood flow to the brain, causing various types of neurological damage.

Fried foods also have a high amount of inflammatory omega 6 oils. These are found in vegetable oils like soybean and corn oil, as well as the fats used to make fried foods.

Often times frying is done at very high temperatures which begins to break down the structure of whatever “food” you are eating. It also changes your food into an unrecognizable form which we don’t have a mouth and stomach to digest properly.

Fried chicken is a perfect example of this. The omega 6 oils are highly inflammatory, when they are heated to such high temperatures it creates advanced glycation end products (AGEs). Aging does that naturally to our bodies but eating foods like fried chicken speeds up the process.  AGEs are found in many foods but fried foods and processed foods contain the highest amount.  AGEs cause inflammation which contributes to every major disease, including degenerative brain disease. This inflammation of course can also lead to milder symptoms such as brain fog.

5. Trans Fats

Trans fats have a negative impact on the brain and nervous system and here are a few reasons why.

Our brain consists of at least 60% fat. We need to eat healthy fat to maintain the vitality of the brain. Because of this need for fat, our body’s natural process is to add whatever fat was consumed into our brain cells.

When trans fat gets incorporated into our cellular membrane, it can reduce the brain’s performance. Studies have linked trans fats to many diseases and disorders. The prominent conditions being; ADD, ADHD, depression, anxiety and Alzheimer’s disease.

Where do Trans Fats, or Trans Fatty Acids come from? Some foods like pork, lamb, milk and butter, have small amounts of trans fats. But the body has a different reaction to these because they are a whole food. Whole foods have a balance of nutrients that our body’s can use much more efficiently.

Foods high in trans fats are made by manufacturers. They heat liquid fats to very high temperatures and add hydrogen. This gives processed foods a longer shelf life and helps the food keep its flavor.

For better brain health here is a list of foods to avoid that are high in trans fats.

  • Margarine
  • Vegetable shortening 
  • Frosting 
  • Baked goods
  • Fried foods 
  • Chips 
  • Crackers
  • Granola bars 
  • Cereals 
  • salad dressings
  • Boxed foods

6. Sugary Drinks

We are all pretty aware that sodas are bad for our health, but why? And what about, tea, fruit juice and energy drinks? Are they all bad for our brain? There are so many drink options at the store these days, it can be confusing. I’m here to help clarify!

Studies were surprising! People who had less than one sugary drink per day, resulted in lower brain volume and a smaller hippocampus. The hippocampus is a very vulnerable part of the brain. It deals with outside stimuli and handles memory and learning. When this part of our brain is effected, it results in different types of neurological damage

This study also included those who drank fruit juice. “High amounts of sugars cause neurological damage because they trigger inflammation“, says Wesley Delbridge, RDN and spokesperson for the Academy of Nutrition and Dietetics.  Needless to say, it’s best so skip on sugary drinks of all kinds. Instead opt for stevia extract, or a squeeze of fresh citrus in your tea.

7. Margarine and Frosting

Processed foods high in trans fats, along with packaged snack foods, may not only be bad for your heart and blood vessels. New research has found that they also negatively impact mental health.

A study from the journal Neurology found that older adults who had high levels of elaidic acid (a type of trans fat) in their blood, were more likely to develop dementia. Dementia is a condition that affects memory, thinking and behavior. It marks the beginning of Alzheimer’s disease or other types of dementia.

High concentrations of the acid were especially associated with those who already had suspected mental decline. According to the study, this was “consistent with neuronal damage.” In layman terms… harmful trans fats can kill brain cells.

8. White Bread and White Rice

Refined carbohydrates that are not even sweet on your taste buds can spike your blood sugar. When your body shoots up glucose, it provides your brain with plenty of energy. But this often leads to a crash, which can make you feel mentally foggy (brain fog). Research shows that refined carbs may increase the risk of Alzheimer’s disease in people who are genetically predisposed to it- which is especially true for those who suffer from diabetes.

A study from the journal Neurology found that older adults who had high levels of elaidic acid (a type of trans fat) in their blood, were more likely to develop dementia. Dementia is a condition that affects memory, thinking and behavior. It marks the beginning of Alzheimer’s disease or other types of dementia.

High concentrations of the acid were especially associated with those who already had suspected mental decline. According to the study, this was “consistent with neuronal damage.” In layman terms… harmful trans fats can kill brain cells.

9. Alcohol

Drinking alcohol in moderation is enjoyable, but excessive consumption can lead to dangerous consequences.

Alcohol use can result in brain volume reduction, brain fog, metabolic changes, and the disruption of neurotransmitters. This disruption in neurotransmitters is linked to poor memory, and even Alzheimer’s disease. What exactly do I mean by neurotransmitters??

Your brain releases chemicals that bind with receptors in the synapses of your brain cells. Molded together they create electrical impulses that move throughout your body. You may have heard of some popular ones: serotonin, dopamine, GABA (gamma aminobutryic acid), and acetylcholine.

These are all neurotransmitters that effect your mood, happiness, sleepiness, etc. What’s worse is the effects of alcohol on your brain can last up to 7 DAYS after you have consumed alcohol!


You may be surprised at how many of these foods that are considered healthy contain high levels of mercury. It is important to consider this when you’re looking for a new diet plan, or even just deciding what type of food to eat on any given day.

For example, tuna fish has been shown to have high levels of mercury which can cause brain damage and other serious health problems in children who consume it regularly.

If you think you or your child might have a brain imbalance such as ADHD, anxiety, or depression, take our assessment quiz here produced by our medical staff.

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