6 Foods That Cause Brain Fog - Neuropedia

6 Foods That Cause Brain Fog

Dealing with brain fog can be incredibly frustrating. A task that should take five minutes ends up taking 20 minutes or more, and focusing on any one thing feels like a heroic effort. 

What you eat can significantly impact how well your brain functions. Certain foods dial down your ability to focus and can create or exacerbate brain fog, forgetfulness, and confusion. 

This article will discuss what causes brain fog and which foods you should avoid if you’re dealing with a foggy head. 

What Causes Brain Fog?

Brain fog can be the result of many different factors. Sometimes it’s just a poor night of sleep that leaves you feeling a bit “off” and unable to focus. 

However, there can be more chronic issues happening behind the scenes that create brain fog more consistently.

These include:

Hormonal Fluctuations 

Hormonal fluctuations are a prevalent cause of brain fog for women. This typically shows up as a sign of PMS during pregnancy or as women move through menopause. The two hormones, estrogen and progesterone, play a crucial role in women’s reproductive health and must maintain a delicate balance for things to run smoothly. When they are out of balance, it can result in issues like anxiety, depression, and of course, brain fog.[1]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6843314/


Another common cause of brain fog is inflammation in your body. Research shows that certain inflammatory molecules, such as histamine, can cause neuroinflammation, which results in symptoms like brain fog and anxiety.[2]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4490655/

Blood Sugar Dysregulation 

Blood sugar dysregulation can create issues with the way your brain consumes energy. Glucose (sugar) is your brain’s primary fuel source, so when there are fluctuations in the way your body processes energy, your brain can be directly impacted. It takes energy for your brain to come up with ideas, send messages, and recall information. When fuel is not efficiently provided to the brain, a foggy-headed feeling is a common side effect.[3]https://hms.harvard.edu/news-events/publications-archive/brain/sugar-brain


Stress, which often leads to feelings of anxiety, can be all-encompassing and overwhelming for your brain and body. When you are in a state of stress, your cognitive resources are taken up by brain chatter and worries, leaving very little leftover for concentration and focus. Unfortunately, more people are feeling the cognitive effects of stress these days than ever before.[4]https://pubmed.ncbi.nlm.nih.gov/32378938/

6 Foods To Avoid If You Have Brain Fog

If you’ve been struggling with brain fog, taking a look at your diet is crucial. Below are the top 6 foods to avoid when you have brain fog.

1. Sugar

As previously mentioned, sugar, in the form of glucose, is your brain’s primary fuel source. When your blood sugar is stable, your brain gets a nice steady stream of fuel and can function optimally. This leads to faster retrieval of stored information, a greater ability to take in new information, and faster processing and conceptualization. 

On the other hand, when your blood sugar is unstable, it can lead to fluctuations in energy that’s sent to your brain. With hypoglycemia (low blood sugar), your brain simply doesn’t get enough fuel to carry out all of its vital processes. With hyperglycemia (high blood sugar), the excess sugar can affect your brain’s functional connectivity, eventually leading to serious issues that may result in cognitive impairment.[5]https://hms.harvard.edu/news-events/publications-archive/brain/sugar-brain

Either way, if you have brain fog, your number one goal should be to keep your blood sugar levels stable. 

It can be challenging to avoid sugar altogether these days, as many manufacturers add sugar to foods that you would never suspect; bread, sauces, even “healthy” meal replacement bars. 

With that being said, you can keep your sugar intake low by keeping an eye on nutrition labels. Always read ingredient labels of packaged foods, and if the nutrition facts say more than 5 grams of sugar per serving, look for an alternative option. 

And as for cookies, ice cream, cake, brownies, candy, and all the other sugar-laden foods out there, try to find alternatives that use lower sugar or no sugar (there are a lot of keto-friendly products that are sugar-free). 

2. Processed Foods

Keeping with the blood sugar discussion, processed foods are stripped of their nutrients and tend to be pretty rough on your blood sugar. What’s more, due to the low-quality ingredients that are often added to processed foods, they tend to also be inflammatory. 

One of the most inflammatory ingredients in processed foods is trans fats. You won’t see trans fats on labels anymore because it’s largely been phased out, but most people don’t realize that manufacturers can still add in trans fat as long as it is only 0.5 grams per serving. This is why avoiding unhealthy processed foods altogether is your best bet.

When it comes to avoiding processed foods, steer clear of foods that are fried, have artificial colors or flavors, or otherwise don’t really represent something that people would consume 200 years ago—for instance, candy bars, colorful cereal, white bread, and so on. 

3. Mercury-Rich Fish

Most people regard fish as one of the most nutrient-rich foods you can consume for brain health. But, unfortunately, our oceans are so contaminated these days that fish are no longer the holy grail of brain health that they used to be. While fatty fish is still an excellent source of omega-3 fatty acids, they’re also a pretty good source of the heavy metal mercury. 

Research shows that among the environmental pollutants out there, heavy metals are one of the most dangerous for neurological health. Mercury in large doses can impact the function of your nervous system and lead to a range of symptoms, including anxiety, irritability, fatigue, headaches, cognitive loss, and even hallucinations.[6]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3395437/

Some of the worst offenders for high mercury include tuna, swordfish, sharks, mackerel, and marlin.

4. Coffee

This one may seem counterintuitive, but coffee may not be your friend if you have brain fog. 

Although coffee, due to its high caffeine content, can give you a little cognitive boost in the moment, the effects that coffee can have on your nervous system may be making matters much worse. 

This is due to its impact on your adrenal glands and the hormone cortisol. As mentioned earlier, hormonal fluctuations are a common cause of brain fog. While imbalances in the sex hormones estrogen and progesterone are common culprits for brain fog, cortisol may also play a role. 

Keep in mind that all of the hormones in your body work together to keep you in balance. This means that when one is out of balance, there is a cascading effect that can also throw others off balance. 

When you drink coffee, it naturally elicits a cortisol spike from your adrenal glands. Cortisol is what gives you that burst of energy and alertness that keeps you coming back for more. However, if you’re caffeine-sensitive or you’re consuming too much caffeine, your adrenal glands can get overworked. This makes it challenging to produce enough cortisol to keep you going. The result? Brain fog, fatigue, and that “tired but wired” feeling.[7]https://www.sciencedirect.com/science/article/abs/pii/S2212962614000054

Many people try to keep upping their dose of caffeine, hoping to reach that place of clear-headed thinking once again. Unfortunately, this usually just makes matters worse, and you end up fatiguing your adrenals even more. 

5. Artificial Sweeteners

Many people turn to artificial sweeteners as a way to avoid sugar. While the intention here is very good, artificial sweeteners may be worse for your neurological health than plain old sugar. 

Aspartame is a common artificial sweetener that’s added to many “sugar-free” products on the market. Research shows that despite its wide use in the food supply, aspartame may act as a neurotoxin, causing oxidative stress and inflammation in the brain. What’s more, due to its chemical makeup, aspartame may cause an imbalance in neurotransmitters such as norepinephrine, epinephrine, and dopamine.

It’s proposed that excessive aspartame ingestion may lead to neurological issues like learning, emotional functioning, irritability, and depression.[8]https://pubmed.ncbi.nlm.nih.gov/24700203/[9]https://www.nature.com/articles/1602866

If you’re going low-sugar, look for ingredients like monk fruit, stevia, erythritol, and xylitol. Stay away from chemical sweeteners like aspartame (also called Equal or Nutrasweet), Sucralose (Splenda), and acesulfame (Ace-K, Sunett, and Sweet One).

6. Conventionally Raised Animal Products

Most, if not all, of the conventionally raised animal products in the US are given antibiotics and hormones. The antibiotics help them stave off illness in their close quarters, while the hormones help them grow faster and produce more milk.

As mentioned, hormone imbalance is one of the most common causes of brain fog. When you consume foods that have been injected with hormones, those hormones may be digested and absorbed and could create imbalances in your natural hormonal activity.[10]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3834504/

Meanwhile, the antibiotics that you consume via conventional animal products can create imbalances in your gut bacteria. The same is true if you take antibiotics over the counter. Your gut bacteria and intimately involved in your gut-brain axis, and research shows that antibiotic use is linked to cognitive issues like confusion.[11]https://www.sciencedaily.com/releases/2016/02/160217180235.htm[12]https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6040098/

Opting for hormone-free and antibiotic-free animal products also means that you’re supporting farms that take care of their animals. These products are also typically much more nutrient-dense with higher levels of healthy fats. 


Brain fog can make everything in life feel a little bit harder. If you’ve been struggling to concentrate or just feel like your brain has a big wool blanket pulled over it, begin to find clarity by looking at your diet. 

In addition to removing the above foods, think about adding in more whole, unprocessed foods like whole grains, fruits, and veggies. Also, try incorporating high-quality animal products like 100% grass-fed beef, organic chicken and eggs, and organic dairy (all hormone and antibiotic-free, of course).

And for an even faster resolution of your brain fog, give nootropic supplements a try. These supplements can help boost brain function and get you back in tip top shape. There are a lot of different nootropics out there, so if you want to find the one that’s right for you try taking this quiz  to find your unique formula. 

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