Nutrition & Brain Function
Hi, my name is Sydney Carroll and I am a dietitian in Seattle, WA. Today’s article marks the beginning of a three-part Nutrition & Brain Health Series. Today we will cover the functions of the brain, the importance of nutrition in providing the brain with energy, and the role that carbohydrates play in feeding our brain. In Part Two we will discuss the effects of restrictive eating on the brain, and in Part Three I will share nutrition tips to support brain health. Ready to learn? Let’s dive in.
Day in and day out, our bodies work to keep us alive. The body’s intricate dance is conducted by a sophisticated internal communication system. Our heart pumps, our lungs breathe, our muscles contract, our brains process information, our digestive tract extracts energy and produces waste, and our nervous system fires. 1
In order to perform all of these important tasks, the human body needs energy. This is where nutrition comes into the picture! When we eat food, our body receives the energy blocks it needs to function. This energy is absorbed and distributed into the body to be used or stored.
How your brain uses energy
Building
Your brain contains nerve cells called neurons. Neurons are responsible for communicating information throughout the body. 2 The brain uses energy to grow new neural connections. It also produces something called a myelin sheath, which is a fatty coating on the neuron that helps with signaling. 3
Microscopic image of a neuron.
Functioning
The brain is responsible for functions that coordinate and operate our whole body. These include; 4 5
Thinking and cognition: decision making and judgement, learning, concentration, organization, problem solving, planning
Sensing through the 5 senses: vision, hearing, smell, taste, touch
Speech & language
Experiencing emotion
Circadian Rhythms: breathing, heart Rate, sleep & wake cycles
Balance and coordination
Energy Needs
Body
An adult human needs to take in a substantial amount of energy each day in order to carry out its functions. This energy is found in food. Nutrition science describes the energy contained in foods in a unit of measure called a calorie. Depending on age, sex, and level of activity, the amount of calories an adult human needs can range anywhere from 1600-3200 calories a day. 6
A Note on Calories: As a dietitian, I do not recommend calorie counting, as it is tedious, time consuming, and often a slippery slope to disordered eating. Though if you are unsure about your baseline energy intake, it may be helpful to ballpark your current energy intake for a few days to see if you are eating enough to meet your energy/calorie needs.
One way to do this is working with a dietitian. Another way is to keep a food journal for a day or two. This information gives you an idea if you are eating enough. Beyond this information gathering stage, the best way to ensure you are meeting your body’s energy needs ongoing is to respond to hunger cues with eating.
You can think of calories like logs that are added to a furnace to fuel a fire. The fire needs new wood added to keep burning and producing heat just like the body requires energy input in the form of calories from eating food to function properly.
Brain
Our brains take a lot of energy to function. In fact, the brain alone uses about 20% of the total energy your body consumes each day. 7 This is pretty remarkable when you consider that the brain makes up only 2% of the body’s weight! 8 One fact that surprises me is that the brain uses the same amount of energy when we are asleep as it does when we are awake.
Carbs are Brain Food
Did you know that the brain’s preferred fuel source is carbohydrates? Carbohydrates, aka carbs, are an essential macronutrient. It is recommended to consume about 1/2 to 2/3 of your daily energy from carbohydrates. 9 A good way to ensure you are getting enough carbs is to include a source of carbs with each snack and meal you eat.
Foods that contain carbs:
Grains, fruit, starchy vegetables, sugar, syrup, honey, dairy and legumes
Carbs & Accessible Energy
Something important to know about the brain is that it does not store energy the way other parts of the body can. For this reason, it needs to be constantly fueled with energy to function. The brain relies on us to eat in order to be supplied with energy. 10
The food we eat breaks down and is circulated in the blood stream in the form of glucose, a small and simple sugar. 11 If the glucose in the blood stream is not used immediately, it is stored in the muscles and liver in a condensed form called glycogen. 12
This set up ensures that at any given moment, the brain will have energy to use. If there is a supply of glucose in the blood, also called blood sugar, the brain will use this. If blood sugar dips too low, a state known as hypoglycemia, the body will mobilize stored carbohydrate from the muscle and liver and convert it back into blood sugar to feed the brain.
In Summary
Time to wrap it up! Here’s what we learned today:
Our brains work really hard for us every day
Our bodies and brains use a lot of energy
We need to eat food to provide our body energy
The brain runs on glucose
Eating carbs is important
Stay tuned for Part 2 and Part 3 of the Nutrition & Brain Health Series! We will cover the impact that undereating has on the brain, and I will share nutrition tips to support brain health.
With Heart,
Sydney
Meet the Author
Sydney Carroll is a dietitian based in Seattle, WA. She supports people who are healing from eating disorders, disordered eating, and body image shame.
Sources
1 University of WA Neuroscience Resources How the Nervous System Interacts with Other Body Systems
2 National Institute of Neurological Disorders and Stroke Brain Basics: The Life and Death of a Neuron
3 University of WA Neuroscience Resources Nutrition and the Brain
4 University of WA Neuroscience Resources That’s Tasty
5 Brain Injury Association of America Brain Functions
6 Dietary Guidelines for Americans 2020-2025 Appendix 2: Estimated Calorie Needs
7 BrainFacts.org How Much Energy Does the Brain Use?
8 Proceedings of the National Academy of Sciences Appraising the Brain’s Energy Budget
10 HopeWay Carbs and Anxiety: How Can Carbs Affect Your Mental Health?
12 Cleveland Clinic Glycogen
