How Sugar and Artificial Sweeteners Affect Your Brain

It’s a well-known fact that diabetes is a serious chronic disease in which the body either doesn’t make enough insulin to control blood sugar (glucose), or can’t use the insulin it makes as well as it should.

Both sugar and artificial sweeteners also have an impact on the brain. And that effect is felt by everyone — not just diabetics.

Dalia Lorenzo, M.D., a neurologist with Miami Neuroscience Institute.

“Any substance that is able to stimulate that dopamine — sort of rewards that circuitry in the brain — has a potential to become habit-forming,” explains Dalia Lorenzo, M.D., a neurologist with Miami Neuroscience Institute, part of Baptist Health. “Addiction is a strong word, obviously, because addiction implies that you are going to go out and seek out the substance. There is some evidence that sugar can become very habit-forming.”

A recent Baptist HealthTalk podcast, Sugar, Artificial Sweeteners & Your Brain, featured Dr. Lorenzo. Host, Jonathan Fialkow, M.D., deputy medical director and chief of cardiology at Miami Cardiac & Vascular Institute, asked Dr. Lorenzo for her insights on the effects of sweeteners — natural and artificial — on mood, memory and even Alzheimer’s Disease. They also talked about the effects of alcohol and caffeine on the brain.

“We all know that excess sugar in our diet can lead to diabetes and weight gain,” said Dr. Fialkow. “But did you ever stop to think about how sugar affects your brain? If you’re thinking — ‘I switched to artificial sweeteners, so I’m O.K.’ — then listen up. They come with their own set of impacts on your brain chemistry.”

Here are question-and-answer excerpts from the Baptist HealthTalk podcast, which can be heard in its entirety here:

Dr. Fialkow: Our brains do need some sugar in the form of glucose as a fuel function. Can you talk about how the brain uses glucose?

Dr. Dalia Lorenzo:
“That’s actually very important because the brain only uses glucose as a fuel supply, as opposed to some of the other organs. So, for example, a muscle can use glucose. But then when it runs out, it has some reserves in the form of the glycogen and fat. In the brain, the situation is different. The brain doesn’t have any stores or reserves of energy, and it really depends minute-to-minute on the glucose that is provided through the circulation. So, it’s minute to minute. And if you really think about it, the brain per weight uses a lot more fuel source, the glucose fuel source, than any other organ in the body.”

Dr. Fialkow: If the brain doesn’t get enough glucose, if our blood glucose drops, what are the effects of the brain?

Dr. Dalia Lorenzo:
“As you can imagine, without the fuel the nerve cells are not going to function well. And so you’ll start to see some problems with performance. For some people, it’ll be hard for them to think. They can’t concentrate. Many times, they can actually start to show symptoms as if they were having a stroke. They can get confused, and if it gets very, very low, then it can do damage. There can be actual damage done to the nerve cells.”

Dr. Fialkow: Now, is there any risk from too high a sugar? So, if the blood sugar is very elevated, does that affect the brain?

Dr. Dalia Lorenzo:
“Yes, definitely… First of all, you can see a lot of mood changes when the glucose gets too high. People get irritable. Many times, they just can’t concentrate well; they can’t think rapidly. They’ve actually done studies where they show that … just can’t think as rapidly.”

Dr. Fialkow: So, if we’re saying that sugar in the diet, especially in its simple forms like fructose and various other forms, might have some negative impact, then are we obviating that negative impact by using artificial sweeteners?

Dr. Lorenzo:
“You’re negating a lot of the caloric effects. You are using substances that have other drawbacks — and specifically drawbacks that can affect you in the brain. There are many different types of artificial sweeteners. Aspartame is metabolized to an amino acid, that is aspartate, which is actually a very stimulatory neurotransmitter. So, that substance actually will overstimulate the nerve cells.

“And if there’s a lot of it, it can overstimulate the nerve cells to the point where it damages or kills the nerve cells. There are a few amino acids that will do that. Aspartate is stimulatory. Glutamate is very stimulatory, and that’s found in other food substances that we’re exposed to, like monosodium glutamate. Also, in a lot of energy drinks there’s taurine. Taurine is another stimulant to the neurotransmitter. So, you have to be a little cautious because you’re trading one thing for another. You’re not having the caloric intake, but you’re now exposing your brain to other effects.”