Neuroscience For Kids

Junk Food, Micronutrients, and the Brain

By Demetria Dickinson (Neuroscience for Kids Guest Writer)
[Edited by Ellen Kuwana, MS]

Junk Food Can Affect the Brain

Junk food is delicious. Humans crave salty, sugary, and fatty foods such as potato chips, candy, soft drinks, and french fries. When we eat these types of foods, our brains reward us by producing the chemical dopamine, which makes us feel good. If we eat a lot of these rewarding foods, the brain makes more receptors for dopamine. Having more dopamine receptors gives us a tolerance to dopamine that makes us want more junk food to get the same effect. Some nutritionists consider junk food to be addictive in the same way as alcohol or nicotine.

Do you ever eat junk food when you feel stressed out or in a bad mood? It might feel good at the time, but this choice actually often makes you feel worse. New research shows that junk food can also affect your mood and brain function -- and not in a good way.

Junk Food has Less Nutrients than Healthy Food

Why do we use the name "junk food" to refer to foods such as candy and chips? It's because these foods don't contain many nutrients. A nutrient gives you energy and helps you to grow.

Macronutrients (macro = large) are essential food components that humans require in large amounts. These include proteins, carbohydrates, and fats. Micronutrients (micro = small) are vitamins and minerals that humans require in small amounts. Junk food is very low in micronutrients.

Studies have shown that the average person in the United States does not get enough micronutrients. As a result, a person's health is not as good as it could be. Other studies have shown that eating better, with foods full of nutrients, can lead to better mental health.

Micronutrients are Essential for Good Health

The brain needs micronutrients to function. Micronutrients help neurons grow and communicate. A person without enough micronutrients can feel tired or in a bad mood. They could also have a hard time learning, focusing, or remembering things.

Also, people who don't eat enough micronutrients may have a higher risk for diseases such as cancer or diabetes. Lack of the micronutrient calcium, for example, can cause a person's bones to get weak, leading to a condition called osteoporosis.

Here are several important micronutrients, how your body uses them, and what foods have them.

Micronutrient	Uses	Major Sources
Potassium	Essential for cells (including neurons) to conduct electrical signals across membranes	Potatoes, apricots, plums, raisins, bananas, beans, spinach, dairy
Vitamin D	Important for bone development. Regulates gene expression. May help with brain function in older adults	Sunlight, fatty fish, fortified foods
Folate (a type of B-vitamin)	Essential for brain development and function	Lentils, beans, asparagus, spinach, other green leafy vegetables and fortified foods
Biotin	Helps cells (including neurons) perform chemical reactions. Important for brain development	Egg yolks, salmon, avocado, liver, yeast
Vitamin B12	Protects nerve fibers, essential for brain function	Fish, shellfish, meat, dairy, eggs

How to Consume More Micronutrients

The best way to get these micronutrients is to eat fruits, vegetables, nuts, whole grains, and other minimally processed foods. A good strategy is to make your meals as colorful as possible by eating different fruits and vegetables. Replace junk food with nutrient-rich food (see suggestions in the table below).

Some processed foods, such as cereal or baby food, have been fortified. Fortified foods have nutrients added to them. Enriched foods lose nutrients during processing and have those nutrients added back in.

Micronutrients don't work alone. Many brain and body functions require more than one of these important molecules. It can be difficult to study the effects of micronutrients because of these interactions. For example, vitamin C helps the body to absorb iron. As such, this interaction means that nutritionists recommend that people with low iron levels take vitamin C along with an iron supplement.

Do supplements help? Maybe. People who don't have enough of a particular nutrient can get healthier when a doctor prescribes a supplement. Too much of a micronutrient can also cause health problems, so it's important to talk with a doctor or nutritionist before trying any supplement.

What Do You Crave?	Try This Healthy Food	Micronutrients In These Foods
Something salty	Baked vegetable chips (such as dried carrots, kale, or sweet potatoes)	Folate, vitamin C, vitamin A, vitamin K, magnesium, iron, calcium
Something oily	Nuts, seeds, avocados	Vitamin B6, vitamin E, magnesium, chromium, manganese
Something sweet	Fruit	Folate, vitamin C, vitamin A
Something crunchy	Popcorn, plain or lightly salted	Magnesium, manganese

Selected References

Kaplan, B., & Rucklidge, J. J. (2021, December 8). Junk food and the brain: How modern diets lacking in micronutrients may contribute to angry rhetoric. The Conversation. Retrieved January 10, 2022.
Reichelt, A. (n.d.). Five ways junk food changes your brain. RMIT News.
O'Connor, A. (2021, March 25). This is your brain on junk food. The New York Times.
Micronutrient Inadequacies in the US Population: An Overview. (2019, April 13). Linus Pauling Institute.
Weisenbeger, J. (2013, September 9). Micronutrients. Innerbody Research.