6 Foods Brain Experts Recommend You Limit for Optimal Cognitive Health

Leading neurologists and psychiatrists reveal the foods most likely to compromise cognitive well-being and mental sharpness.

By Medha deb

Created on Sep 28, 2025

Leading neurologists and psychiatrists reveal the foods most likely to compromise cognitive well-being and mental sharpness.

Your brain is your most vital organ when it comes to focus, mood, and memory. Scientific research shows that the foods you choose have a direct and lasting impact on its health. While a well-balanced, whole-food-based diet can sharpen cognition and lower your risk for neurodegenerative diseases, certain foods may actually heighten your risk of memory problems, mood disorders, and even long-term cognitive decline. We spoke with leading neurologists and psychiatrists to determine which foods pose the greatest threat—and what you can do to support your brain health instead.

1. Artificial Sweeteners

Artificial sweeteners, like aspartame and saccharin, are marketed as low-calorie alternatives to sugar. However, brain doctors urge caution:

Neurotransmitter disruption: Artificial sweeteners may affect the brain’s chemical messengers, with some evidence suggesting an impact on mood and cognition.
Potential for anxiety and headaches: Some studies have linked certain sweeteners to symptoms like headaches, irritability, and anxiety, especially in sensitive individuals.
Glucose intolerance: Regular consumption of artificial sweeteners may alter gut microbiota, leading to issues with blood sugar control. Impaired regulation of glucose is a known risk factor for cognitive impairment and dementia.

Expert note: Brain health experts recommend minimizing artificial sweeteners. Opt for natural alternatives like stevia or simply reduce added sweetness in foods and beverages.

2. High-Mercury Fish

Mercury is a neurotoxin that accumulates most in large predatory fish, such as swordfish, king mackerel, shark, and certain types of tuna. According to brain specialists:

Mercury targets the cerebellum, responsible for balance, coordination, and visuals.
Long-term exposure affects memory, mood, and cognitive function, especially in sensitive populations and developing children.
The effects can be subtle or severe depending on the dose and frequency.

What you can do:

Limit consumption of high-mercury fish to once per week or less.
Choose lower-mercury options such as salmon, sardines, trout, and anchovies.
Follow EPA and FDA guidelines, particularly for pregnant women, young children, and vulnerable groups.

3. Prepared Biscuits and “Flaky” Packaged Baked Goods

The convenience of prepared or packaged biscuits and flaky pizza crusts comes at a cost. Brain experts call out these products because they often contain trans fats, even after regulatory crackdowns:

Trans fats are linked to brain shrinkage, inflammation, and impaired nerve transmission.
Eating foods with trans fats, even in small amounts, may damage memory and slow cognitive processing.
Manufacturers can list “0g trans fats” if per-serving amounts are under 0.5 grams—meaning you might still be getting it in trace yet cumulative amounts.

Check ingredient lists for “partially hydrogenated oils” and avoid regular consumption of:

Packaged biscuits
“Flaky” prepared pizza or pastry crusts
Margarine and microwave popcorn

4. Sugary Drinks

Sodas, sweetened teas, energy drinks, and even some fruit-flavored beverages are loaded with added sugars. Here’s why neurologists warn against them:

High sugar intake drives insulin resistance, which increases the risk of developing dementia and memory problems.
Frequent consumption is linked to brain inflammation, disrupted neuron communication, and a higher risk for mood disorders.
Sugar-sweetened beverages add unnecessary calories but no nutrients, often displacing water, tea, and nutrient-rich drinks from the diet.

Switch to: Water, unsweetened herbal teas, or naturally flavored sparkling waters to satisfy your cravings without risking cognitive health.

5. Gluten (For Sensitive Individuals)

Gluten is a protein found in wheat, barley, and rye. While most people can consume gluten without harm, brain-focused doctors highlight that:

Individuals with celiac disease or gluten sensitivity may experience neurological symptoms like headaches, mood changes, and memory difficulties when exposed to gluten.
Even without classic digestive symptoms, gluten can trigger brain-related issues in some, sometimes called “gluten ataxia.”
Currently, there’s no evidence that avoiding gluten benefits brain health in people without a sensitivity or celiac disease.

What to do: Consult a health provider if you suspect a gluten issue. Otherwise, whole grains (including wheat) provide beneficial brain nutrients and fiber when tolerated.

6. Processed and Ultra-Processed Foods

Ultra-processed foods—including fast food, packaged snacks, candy bars, and sodas—make up a significant portion of the standard Western diet. Brain experts caution that:

Ultra-processed foods are high in added sugars, trans and saturated fats, and artificial ingredients while being low in nutrients vital to brain function.
Regular consumption leads to increased inflammation, obesity, and higher risk of memory problems and neurodegenerative diseases.
These foods often crowd out nutrient-rich options, reducing intake of brain-friendly vitamins, minerals, and antioxidants.

A recent study found a significant link between frequent consumption of ultra-processed foods and an elevated risk of dementia. Even small daily amounts had an impact, making moderation key to protecting brain health.

Brain-Boosting Foods: What Should You Eat Instead?

While it’s important to limit risky foods, you can make a powerful difference to your brain by emphasizing nourishing alternatives. Nutritionists and researchers suggest the following are especially protective:

Leafy green vegetables (such as spinach, kale, and broccoli)
Berries (like blueberries, raspberries, and strawberries)
Whole grains (oats, brown rice, farro, etc.)
Fatty fish low in mercury (salmon, sardines, trout)
Nuts and seeds
Beans and legumes
Olive oil as the main dietary fat
Poultry and eggs in moderation

Mediterranean and MIND Diets have been associated with lower risk of Alzheimer’s and cognitive decline. Their key strategies include:

More vegetables and whole plant foods
Fewer red meats, processed foods, and sweets
Consistent inclusion of healthy fats, particularly olive oil and nuts

Brain-Risky Food	Reason for Concern	Safer Alternative
Artificial sweeteners	May affect brain chemicals and blood sugar control	Small amounts of natural sweeteners, stevia
High-mercury fish	Mercury toxicity impacts balance and memory	Low-mercury options like salmon, sardines
Prepared biscuits, flaky baked goods	Trans fats increase inflammation and memory loss	Homemade or whole-grain baked items without industrial fats
Sugary drinks	Linked to insulin resistance and cognitive issues	Water, herbal tea, unsweetened coffee
Processed & ultra-processed foods	Associated with dementia risk, low in nutrients	Fresh fruits, vegetables, minimally processed snack choices

Frequently Asked Questions (FAQs)

Q: Is it necessary to avoid all the listed foods completely to protect brain health?

A: Experts stress that moderation is key. Occasional consumption is unlikely to cause harm for most people. Making these foods a rare treat, rather than a staple, is a practical and protective strategy for cognitive health.

Q: Can occasional consumption of high-mercury fish or processed snacks have immediate effects?

A: Occasional exposure is unlikely to cause immediate brain harm for healthy adults, but consistency over time increases risk. It’s the cumulative effect of regular consumption that experts worry about.

Q: What should I eat for optimal brain power?

A: Emphasize more vegetables (especially greens), berries, whole grains, nuts and seeds, olive oil, fish, beans, and lean poultry. These support antioxidant defenses, reduce inflammation, and promote robust brain function at any age.

Q: Are gluten-free diets beneficial for everyone’s brain?

A: Only people with diagnosed celiac disease or gluten sensitivity will benefit cognitively from avoiding gluten. For others, whole grains provide essential brain nutrients and should be included as tolerated.

Q: Where can I learn more about brain-healthy nutrition?

A: Registered dietitians, reputable brain health organizations, and neuroscientific research journals offer ongoing advice. Look for information based on strong scientific evidence and consult your healthcare provider for personalized guidance.

Key Takeaways for Brain-Smart Eating

Limit artificial sweeteners, high-mercury fish, prepared biscuits, ultra-processed foods, and sugary drinks for better brain health.
Balance is crucial. Occasional treats aren’t harmful, but daily habits shape cognitive destiny.
Build a brain-protective plate centered on fresh produce, lean proteins, healthy fats, nuts, seeds, and whole grains.
Consult healthcare professionals for individual concerns, especially if you have a family history of neurodegenerative disease.

Making these mindful changes can nourish your brain and support cognitive clarity, energy, and mood throughout your life.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

Read full bio of medha deb