Sugar and Your Brain

Sugar is found in 75 to 80 percent of our food sources, and once it’s converted to glucose, it’s the primary fuel source for the entire body, including the brain. Because of all the nerve cells in the brain, it uses one-half of all the sugar energy in the body. Optimal brain function is dependent upon glucose levels. If there is not enough glucose being supplied to the brain, things like memory, learning and overall cognitive function are impacted negatively.

However, as important as sugar is to the brain, consuming too much can damage the brain. According to Natasa Janicic-Kahric, associate professor of medicine at Georgetown University Hospital, “Many Americans eat about five times the amount of sugar they should consume.”

The USDA states that you should consume no more than 40 grams, or 10 teaspoons, of sugar per day. Sugar is everywhere in the food we eat, particularly in processed or “convenience” foods. The majority of these have added sugars as a preservative, to enhance flavor or both. Many “low-fat” products, for example, have added sugars to replace the flavor of the fat.

Neuroscience classifies food as a “natural reward.” A natural reward is something that creates pleasure in the brain, which ensures that the behavior is repeated. We have to eat in order to live, therefore our brain reacts to food by releasing dopamine and serotonin. These are the “mood-boosting” chemicals in the brain that are released when we do something that feels good. They motivate us to continue doing the activity that created the pleasure. Consuming sugar will stimulate these chemicals and can create a vicious cycle of wanting more and more sugar in order to keep feeling good.

So what happens in the brain when we consume sugar?

When you eat, the taste receptors on your tongue send a signal to the brain, which then activates a surge of hormones, dopamine included, to be released. According to neuroscientists Nicole Avena and Jordan Gaines Lewis, over-consumption of sugar “hijacks the brain’s reward pathways and kickstarts a series of events – loss of control, cravings and increased tolerance to sugar.” Similar to an addiction to drugs, more sugar and more frequent consumption of sugar is needed to achieve the same level of pleasure.

In a 2012 study done on rats at UCLA, researchers discovered that a diet high in sugar impairs learning and memory by damaging the synaptic activity, literally slowing down the brain. The high sugar intake caused the rats to develop insulin-resistance. Insulin controls blood-sugar levels and also strengthens the synaptic connections between brain cells. So, lower insulin levels caused by sugar consumption was linked to impaired cognition in the rats.

Over-consumption of sugar can also cause unstable moods as well as contribute to depression and anxiety. When you eat a sugary food or drink a soda, your blood-sugar level spikes suddenly, then decreases as the body processes the sugar. When your blood sugar drops, you may feel irritable or experience fatigue, which causes you to crave more sugar in order to increase your blood-sugar level. High blood-sugar levels have been linked to inflammation in the brain, which has been named as a possible cause of depression. Also, continued stimulation of serotonin can deplete the brain’s supply of this chemical, which can contribute to depression.

Endocrinologist Dr. Medha Munshi discovered, in a 2013 study, that research shows “evidence that the brain is a target organ for damage by high blood sugar.” Insulin-resistance and blood-glucose levels, hallmarks for diabetes, are also associated with a greater risk for developing Alzheimer’s and other neurodegenerative disorders.

It’s clear that a high-sugar diet can potentially do damage to brain function and overall mental health. The occasional sugary treat is harmless, but it’s important to be aware of just how much sugar we are actually consuming. Following a low-sugar diet will keep the brain healthy and functioning properly.

Be Well Tips

  • Speak to a physician before changing your diet.
  • The USDA says 10 teaspoons or less of sugar per day.
  • Sugar consumption has been linked to depression and Alzheimer’s disease.
  • Sugar causes blood-sugar levels to spike.
  • A low-sugar diet will keep the brain healthy.