Omega-3s, particularly a variety called DHAs, have been shown in studies to be “associated with better non-verbal reasoning, mental flexibility, working memory, and vocabulary,” says Lisa Mosconi, PhD, author of Brain Food: The Surprising Science of Eating for Cognitive Power. And a vitamin B12 deficiency, she says, has been shown to trigger “cognitive deficits” similar to what happens to people with dementia. (A B12 deficiency can also manifest as depression and fatigue, and has been linked to neurological disease.)

Do you lose any brain-boosting nutrients by going vegan?

https://www.wellandgood.com/good-food/vegan-diet-brain-health/

Possibly. Research shows it can be a lot harder to get all the vitamins, minerals, and nutrients essential for proper health with such a limited diet. That’s particularly true when it comes to brain health—in nixing all animal products, you’re eliminating key sources of omega-3 fatty acids and vitamin B12. Omega-3s, particularly a variety called DHAs, have been shown in studies to be “associated with better non-verbal reasoning, mental flexibility, working memory, and vocabulary,” says Lisa Mosconi, PhD, author of Brain Food: The Surprising Science of Eating for Cognitive Power. And a vitamin B12 deficiency, she says, has been shown to trigger “cognitive deficits” similar to what happens to people with dementia. (A B12 deficiency can also manifest as depression and fatigue, and has been linked to neurological disease.)

And that’s where veganism can make things tricky. DHA omega-3s are generally only found in seafood, says Dr. Mosconi. Plant-based foods do contain omega-3s, she adds, but it’s a different type known as ALA. “The brain is able to convert ALA to DHA, but the conversion is not very efficient,” she says—so relying on just foods with ALAs for your DHA needs is not going to cut it. There is one vegan-friendly exception to this rule: Supplements made from algae, Dr. Mosconi says, have DHA but are okay for vegans to eat.

As for vitamin B12, Dr. Mosconi says, “the good bacteria in our gut make some vitamin B12, but the rest needs to be obtained from the diet, which means animal food and fish since plant-based foods contain no B12.” This would be bad news for vegans except that supplements are available in vegan-friendly form. You can also look for fortified foods like nutritional yeast, which contains tons of vitamin B12.