Your brain is one of the most energy-hungry organs in your body, relying on a steady supply of nutrients to think, focus, and remember. Many of the foods that support overall health also help keep your brain sharp, but some can do the opposite.
Here are five kinds of foods and drinks that are the worst for your brain health, according to research.
1. Alcohol (Yes, Even in Moderate Amount)
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Alcohol interferes with normal brain function, making it harder for brain cells to communicate and do their jobs. Over time, it can damage nerves, impair memory, and affect mood and behavior. Drinking heavily or frequently is also linked to problems with decision-making and emotional control. In the long run, sustained high alcohol intake can raise the risk of dementia.
Brain damage linked to alcohol is most often associated with long-term, heavy drinking. But it doesn’t take that much for alcohol to affect the brain, which you might notice after just one drink. Studies have found that even light or moderate drinking can lead to some deterioration of the hippocampus.
2. Fish High in Mercury
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Mercury is a heavy metal known to be neurotoxic, meaning it can damage the brain. Most people are exposed to mercury through their diet, particularly by eating certain types of fish, such as tuna and mackerel.
Mercury can harm the central nervous system. That risk is why health agencies set recommendations on how much mercury-containing fish people can safely eat each week.
Being mindful about fish choices is especially important for children, whose brains are still developing, and for pregnant people, since mercury exposure during pregnancy can interfere with fetal brain development. In severe cases, high levels of mercury exposure have been linked to symptoms such as hallucinations and psychosis.
3. Sugar and Artificial Sweeteners
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We need some sugar, specifically glucose, for the brain to use as energy. But when we consume more than needed, sugar can start to have negative effects.
Sugar can trigger the release of dopamine, a feel-good brain chemical, which explains why we have sugar cravings sometimes. Repeated, frequent blood sugar spikes might affect energy, mood, and sleep.
Artificial sweeteners have also been linked to poorer brain health, including a higher risk of cognitive decline, stroke, and dementia.
4. Refined Carbs
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The body can quickly break down refined carbohydrates, such as white rice and white bread, and convert them into glucose. This can give a quick boost of energy, but refined carbs have similar effects to high sugar intake.
Your brain does need carbohydrates to function, but whole grains don’t appear to trigger the same harmful inflammation, blood sugar spikes, or negative effects on the brain as refined carbs do.
In fact, swapping refined carbs for whole grains may help protect cognitive function and lower the risk of age-related brain conditions like dementia and Alzheimer’s disease, which some studies have linked to diets high in refined carbohydrates.
5. Ultraprocessed Foods
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Heavily processed foods often contain high levels of trans fats, along with added sugar or artificial sweeteners, sodium, preservatives, and other additives linked to negative health effects.
Ultraprocessed foods tend to pack many of these ingredients into a single product, often in large amounts. Research has linked diets high in processed foods to a greater risk of neurodegenerative conditions, including dementia and Alzheimer’s disease.
It’s not just packaged snacks—some foods like deli meats are also considered ultraprocessed.