Can a Vegan Diet Cause Brain Fog or Memory Loss?

Brain fog is the general inability to access memories or perform cognitive tasks. It can feel like everything is hazy—or like you’re groggy, even though you’ve been awake all day. Brain fog can have many causes, but it’s often linked to our diet.

Vegan diets do not typically cause brain fog or memory loss. However, vegans may need to monitor specific nutrients, such as DHA, vitamin B12, and iodine, which are linked to brain health. Many authorities recommend vegans take an algae-based DHA (omega-3) supplement for peak brain health.

Below, I’ll share more about the 4 nutrients most commonly discussed when looking at vegans and brain fog—and how you can get them. I’ll also look at the pros and cons of eating fish for brain health. Then I’ll share 5 practical tips for maintaining your memory!

Vegan Nutrition and Brain Fog

Our society tends to be suspicious about vegan nutrition. Whether it’s protein or B12, there are no shortages of concerns when it comes to the vegan diet. Some people have questions about brain fog and memory issues.

Most vegans have no problem with brain fog or memory loss. But there are a few key nutrients linked to brain health that can potentially be lower on a vegan diet. Let’s take a look at what those are.

1. DHA (Docosahexaenoic Acid)

DHA is a vital omega-3 fatty acid that plays a role in everything from brain health to our skin. Research shows that DHA is linked to healthy cognitive functions. Making sure you get enough DHA is vital for vegans.

While it’s possible to get omega-3 fats from vegan plant foods—like flax, walnuts, and hemp seeds—this is a less bioavailable form of omega-3, called alpha-linolenic acid (ALA). Your body still needs to convert that to DHA.

And some of us are not very good at converting it. This has led many vegan authorities, including Dr. Michael Greger, to recommend supplementing with DHA,

The good news is that algae-based vegan omega-3 supplements with DHA are shown to be just as effective as fish oil that non-vegans take. (See my post about vegan omega-3 vs fish oil for more on that.)

So there’s no need for vegans to have lower DHA levels. And there’s no need for vegans to eat fish to raise their DHA levels, either.

Personally, I take the Future Kind Essential Multivitamin every day for my DHA and omega-3s. It also includes vitamin D and B12, the other nutrients Dr. Greger recommends supplementing as a vegan. Read my review post for more on this multivitamin.

2. Vitamin B12

Vitamin B12 maintains many of our body’s systems, including healthy nerve cells. Low levels of B12 are associated with memory loss. This means getting enough B12 is key to fighting off brain fog.

Vegans tend to have a bit lower B12 levels than non-vegans. This is because animal foods naturally contain some B12, and obviously, vegans aren’t eating those foods.

However, as with DHA above, this issue with vitamin B12 is easily prevented. Supplemental B12 is shown to be effective in raising B12 levels and avoiding deficiency.

“Deficiency can be prevented at a very low cost and low hassle by taking a multivitamin with the average daily recommended amount of 2.8 micrograms of B12.”

– Dr. Meir Stampfer, professor at Harvard T.H. Chan School of Public Health (source)

Like I said above, I take the Future Kind Essential Multivitamin to get my daily B12 and DHA. But you could also eat B12-fortified foods like plant-based milks.

The B12 in vitamin supplements and injections is derived from bacteria—not animals—so it’s safe for vegans. (I actually have a post explaining how B12 supplements are made.)

3. Choline

One of the foods highest in choline: Broccoli.

Choline is another vital nutrient the human body needs.

Not getting enough choline can lead to liver problems and, according to some sources, brain fog. There are studies showing higher cognitive performance with higher choline intake.

Thankfully, there are many plant-based sources of choline:

  • Cruciferous vegetables like broccoli, cauliflower, and Brussel sprouts
  • Tofu and soy products
  • Peanut butter
  • Peas
  • Carrots
  • Kidney beans
  • Quinoa
  • Kiwi
  • And many more

We tend to get enough choline from our diets. In fact, getting too much choline may contribute to worse outcomes for certain types of cancer, plus higher heart disease risk. (source)

There is some speculation out there that vegans may not get enough choline. But here’s what Medical News Today has to say about it:

“Although some people believe that vegetarians and vegans may be at risk of choline deficiencies, there is only mixed evidence to support this.

In fact, some of the foods with the highest choline content include soybeans, potatoes, and mushrooms. Eating a nutritious diet that focuses on whole foods should be enough to prevent deficiency.” (source)

Overall, choline is probably not a problem for many vegans. If you suspect for any reason that it could be for you specifically, I’d suggest eating more of the high-choline foods listed above.

4. Iodine

Iodine is vital for both cognitive performance and brain development. Iodine deficiencies are still the single greatest contributor to preventable brain damage in infants.

Thyroid function is also directly linked to getting enough iodine. When iodine levels are low, people start to feel sluggish due to thyroid problems.

Therefore, getting enough iodine can help prevent brain fog.

Iodine is plentiful in the diet in most developed countries. In America, iodine is added to table salt to increase its general supply. If you just use iodized table salt on your food, that is likely enough. (source)

You can also get iodine from seaweed. It can be healthier than getting it from iodized salt because, well, getting too much salt isn’t healthy. However, you should take caution that you don’t get too much iodine from seaweed.

Some seaweeds, like kelp, can quickly give you too much. And too much can be just as bad as not enough. So if you’re getting iodine from seaweed, look into the specific serving sizes!

Iodine can also be found in vitamins and supplements. Future Kind has a vegan iodine supplement that I’d recommend if you worry you could be low on this nutrient.

Is Fish a Solution For Brain Fog?

do vegans eat fish
Fish contain brain-helping DHA… but many types also contain brain-harming mercury.

Given the compelling evidence linking DHA and other essential nutrients to memory and cognitive health, is adding fish to a vegan diet a solid solution to these problems?

The answer is that, yes, it’s one possible solution. But there are some problems that fish can also bring to a diet.

Fish are a historically important part of the human food supply. They do supply essential fatty acids that could theoretically reduce brain fog. But our modern fish supply isn’t as reliable as it used to be. Pollution has changed how we relate to fish as a food source.

Today’s fish supply contains mercurywhich can potentially cause brain fog. This “fish fog” is caused by a buildup of mercury in the body.

In fact, here’s a story of a woman who ate fish every day and ended up with significant brain fog and memory loss. The mercury levels in her blood were found to be over 4x of the normal range (43 ng/ml). She recovered after removing fish from her diet.

Granted, she was eating a lot of fish, including swordfish, which is extra contaminated. Not everyone who eats fish will get brain fog like she did.

But the point is that fish is not actually “the solution.” Look at the specific nutrients of concern. Get your DHA somehow. More and more authorities recommend algae-based omega-3 supplements as a cleaner, vegan alternative to fish.

Learn more here, or check out my review of the multivitamin I take to get DHA and other key vegan nutrients.

Common Causes of Brain Fog For Everyone

If you’ve recently adopted a vegan diet or you’ve been vegan for years and you’re concerned about brain fog, it might not be your diet that is to blame. There are plenty of people who have been vegan for decades without brain fog.

Personally, I’ve been vegan for 14 years, and I don’t feel hindered by my brain health at all. I work in an intellectually rigorous field, and I recently completed a year of graduate school with a 4.0 GPA.

Many vegans report increases in mental clarity early after making the switch to plant-based. So if you’re struggling, it could be something besides diet entirely.

Brain fog is a general symptom of a wide range of problems. So here are a few non-diet factors you should check out if you’ve had a sudden cloud of brain fog.

Mental Health

Mental health problems from anxiety to dementia can all cause brain fog. In fact, mental illness can even contribute to memory loss.

While our diets and our minds are closely linked, even individuals with the most well-rounded vegan diets can still experience mental illness.

Sedentary Lifestyle

Staying sedentary is another cause of brain fog outside of diet. Whether the sedentary lifestyle is caused by illness or just an old-fashioned lack of fresh air, it can lead to brain fog.

When we get up and get moving, we can dramatically improve our mental clarity, memory, and clear up brain fog. Even short bouts of activity can help you cut through the fog.

Research has shown that regular exercise also helps improve your memory and retain your brain function as you age.

Medications and Medical Conditions

All medications come with side effects. One of the most common sets of side effects are changes to our cognitive abilities and to our moods. Both of these factors come into play when it comes to brain fog.

Medicines including methotrexate, a common treatment for arthritis; medications for mental illness; and hormonal medications can all have brain fog as a side effect.


Injuries, including concussions, are common causes of brain fog.

While we tend to associate a concussion with a dramatic injury, the reality is that concussions can actually be caused by seemingly mild incidents. Even minor concussions can cause brain fog.

If you’ve experienced a concussion yourself, you know this to be true. Often, you’ll just feel like your brain is not fully available to help you answer questions or solve problems.

This can also happen with fevers and other physical illnesses besides injuries.

So how should you keep your mind healthy and prevent brain fog while on a vegan diet?

5 Tips to Avoid Vegan Memory Loss and Brain Fog

Keeping our minds healthy is a lifelong project. See which of these 5 tips you’re not implementing yet:

1. Exercise

Keeping the body moving is one of the keys to preventing brain fog. Exercise has been shown to help all kinds of mental health issues from alleviating brain fog to helping with mental illness. Even a little exercise can help.

Light jogging, yoga, and active stretching are all easy ways to start to introduce activity into your daily life. Doing just a small workout daily can boost your mental health.

2. Sleep

Sleep is fundamental to human health. The longer we go with poor sleep habits, the worse our health becomes. Brain fog sets in quickly when sleep is poor.

We’ve all woken up from a rough night of sleep feeling groggy and out of it. This is brain fog caused by poor sleep.

Luckily, getting the sleep you need can quickly reverse this. Setting regular bedtimes, taking a nap, or sleeping in can all help you get better sleep.

3. Improve Your Diet

There is a reason the term “junk food vegan” exists. It’s possible to eat unhealthy even as a vegan. So look at your diet and be honest about what could be improved.

A little junk food every now and then likely won’t do any harm. But having a diet that is dominated by processed snack foods can lead to brain fog.

Shake up your diet by trying new recipes or adding in more fresh produce. There are plenty of healthy alternatives to junk food that still deliver flavor while helping you achieve mental clarity.

4. Workout Your Brain

Your brain is like a muscle: The more you exercise it, the stronger it becomes. The link between brain games and memory loss is not entirely clear—but there are still benefits gained from working out your mind.

When we engage in more cognitive activities, we also tend to socialize more and get more physical activity in our lives. This combination of mental and physical activity can help keep our cognitive abilities up throughout our lives.

5. Take a DHA/EPA Supplement

I mentioned this a few times above, but it’s a big key for vegans.

DHA is the nutrient most commonly associated with brain fog issues—and it’s one that many vegans don’t get in their diet.

I recommend Future Kind vitamins because they’re all-vegan company and their formulations are on-point.

They have a vegan multivitamin with DHA (that’s what I take). Or they also have a separate vegan omega-3 supplement if you’re already getting B12 and vitamin D from other sources.