We have all heard the touted benefits of “smart” foods that can boost our brain power by increasing alertness, memory, and even brain cell production. While we try to eat our way to good physical and mental health, we often ingest willingly, and unknowingly, foods that can have an impact on our brain development. These “dumb” foods (and food additives), ranging from monosodium glutamate (MSG) to tofu, can be toxic to our brain cells even in small doses, affecting our alertness, memory, mood, and nervous system.

1. Caffeine

Many of us rely on this stimulant to get us through the day, whether we have one cup or three cups of coffee a day. When we drink caffeine, the body absorbs it quickly and passes it to the brain, according to Medline Plus, and then gets excreted through urine hours later. Although it is not associated with brain damage, psychologists like Dr. Lauren Napolitano at Bryn Mawr Hospital in Pennsylvania believe in order to get a clear picture of someone’s baseline mental health, you must eliminate coffee. “The number one thing people with mental health issues should avoid is caffeine,” Napolitano told Medical Daily in an email. “Many people drink caffeine in order to combat symptoms of depression (lethargy, anhedonia) but unintentionally throw themselves into a manic episode or a panic attack.” Although caffeine withdrawal may hurt for a day or two — you may find yourself accompanied by a headache — people tend to feel much calmer without it.

2. MSG

It is common to get a headache, a tightness in the chest, or even have vivid and bizarre dreams after eating Chinese food. A popular additive in Asian cuisine — MSG — is used by chefs to enhance the flavor, but it can wreak havoc on your brain health, attacking the brain stem. As an excitotoxin, MSG overstimulates neuron receptors, causing a firing of impulses that they become extremely exhausted, and die hours later. Dr. Chad Laurence, a corrective chiropractic in Delaware, warns any MSG derivative is negatively impactful on the brain. “MSG is hidden in various sources, including: natural flavors, spices, hydrolyzed protein, autolyzed yeast extract, sodium caseinate, bouillons, soy protein isolate,” among many others, Laurence told Medical Daily in an email.

3. Precooked and Processed Foods

These types of foods overstimulate the production of dopamine, also known as the “pleasure” neurotransmitter that leads to excessive cravings. Precooked and processed foods contain preservatives, additives, dyes, and artificial flavors that have the ability to affect our behavior and our cognitive functioning. “Processed foods and any foods that are hyper-allergenic can take a toll on brain health,” said Brandon Mentore, sports nutritionist, and functional medicine practitioner, to Medical Daily in an email. “The more chemical and synthetic the compounds in food are the harder they are to digest and detoxify.”

A 2012 study published in the Journal of Clinical Investigation found high-fat processed food consumption can cause damage to the hypothalamus part of the brain. This area is responsible for regulating hunger and thirst levels, and the body’s natural rhythms and cycles.

4. Salt

It comes as no surprise a high salt intake can take a negative toll on our health, including our mental health. Salt helps with the transmission of nerve impulses and water migration in and out of cells. “A high salt intake particularly table salt can cause cellular activation to be hypertonic, which can be a good thing but in excess over time your body’s ability to relax and have proper fluid balance and nerve transmission will be down regulated as a protective measure in the body,” Mentore said.

A 2011 study published in Neurobiology of Aging found poor vascular health — associated with high-sodium diets, and a lack of exercise — may be related to a faster cognitive decline in old age. Participants with the highest daily sodium intake — defined as 3,091 milligrams a day or more and a sedentary lifestyle — were more likely to show declining scores on tests of cognitive function over a three-year period compared to their counterparts. Consuming processed foods can increase the risk of dementia, since they are typically high in sodium.

5. Sugar

If you’re constantly seeking a sugar rush, you could be putting your mental health in danger. Consuming high amounts of sugar over a period of time can cause neurological problems ranging from memory to the ability to learn. Too much sugar in the blood can slow down your brain cells’ use of insulin to break down sugar to help process thoughts and emotions. "The body’s ability to monitor this is usually handled by insulin but if consumption of sugar is too high inflammation encroaching on the brain will happen at some point,” Mentore said.

A 2012 study published in the Journal of Physiology found fructose slows down the brain and memory functions in rats. High fructose corn syrup is widely used in the U.S. and alters the brain’s ability to learn and remember information. Americans should try to limit their sugar intake, which includes high-fructose corn syrup, and high-carb foods.

6. Tofu

This may come as a surprise to many, but the “healthy food” can be harmful if consumed in large quantities. A 2008 study published in Dementias and Geriatric Cognitive Disorders found evidence that a high consumption of tofu is associated with worse memory, especially for those over 68. Although it is not entirely clear what effect soy products high in phytoestrogens have in the aging brain, they can heighten the risk of dementia and lower memory function.

7. Trans Fat

Trans fat is known to raise our “bad” (LDL) cholesterol levels and lower our “good” (HDL) cholesterol levels. A high consumption of trans fat can even lead to brain shrinkage. The synthetic trans fats increase the amount of oxidation in our body and create an arterial stiffness, Mentore explained. “All of this plays into the vascularity and the plasticity of your brain and nerve transmission. This can increase inflammation and plaguing in the brain."

A 2012 study published in Neurology found a high intake of trans fat is linked to brain shrinkage. Scientists scanned the brains of the participants to ensure the brain volume would be measured accurately. It was those who had high vitamin levels who had larger brains, and vice versa. Those with high trans fat diets were found to experience brain shrinkage similar to people with Alzheimer’s Disease.

Avoid or limit the consumption of these foods to age-proof your brain at any age.