HOW SUGAR AFFECTS THE BRAIN

 

Picture warm, goey cookies, cunchy candies, velvety cakes, waffle cones piled high with ice cream. Is your mouth watering? Are you craving dessert? 

Why?

What happens in the brain that makes sugary foods so hard to resist? Sugar is a general term used to describe a class of molecules called carbohydrates, and its found in a wide variety of food and drink.

Just check the labels on sweet products you buy. Gluscose, fructose, sucrose, maltose, lactose, dextrose, and  are all forms of sugar. So are high fructose corn syrup, fruit juice, and honey.

And sugar isnt just in candies and desserts, its also added to tomato sauce, yogurt, dried fruit, flavored waters, or granola bars. Since sugar is everywhere, its important to understand  how it affects the brain.

What happens when sugar hits your tongue?

And does eating a little bit of sugar  make you crave more? You take a bite of cereal. The sugars it contains activate the sweet taste receptors, part of the taste buds on the tongue.

These receptors send a signal up to the brain stem, and from there, it forks off into many areas of the forebrain, one of which is the cerebral cortex.

Different sections of the cerebral cortex process different tastes:  bitter, salty,  and in our case sweet. From here, the signal activates the brain's reward system. This reward system is a series of electrical and chemical pathways  across several different regions of the brain.

Its a complicated network, but it helps answer a single, subconscious question: should I do that again? That warm, fuzzy feeling you get when you taste grandma's chocolate cake? Thats your reward system saying, mmmm, yes!

And its not just activated by food. Socializing, sexual behavior, and drugs are just a few examples of things and experiences that also  activate the reward system. 

But overactivating  this reward system kickstarts a series of unfortunate events: loss of control, craving, and increased tolerance to sugar.

Lets get back to our bite of cereal. It travels down into your stomach and eventually into your gut. And guess what? There are sugar receptors here too. They are not taste buds, but they do send signals  telling your brain that you are full or that your body should produce more insulin to deal with the extra sugar you are eating.

The major currency of our reward system is dopamine, an important chemical or neurotransmitter.  There are many dopamine receptors in the forebrain, but they are not evently distributed.

Certain areas contain dense clusters of receptors, and these dopamine hot spots are a part of our reward system. Drugs like alcohol, nicotine or  send dopamine into overdrive,  leading some people to constantly seek high, in orher words to be addicted.

Sugar also causes dopamine to be released, though not as violently as drugs. And sugar is rare among dopamine inducing foods. Broccoli for example has no effect, which probably explains why its so hard to get kids to eat their veggies.

Speaking of healthy foods, lets say you are hungry and decide to eat a balanced meal. You do and dopamine levels spike in the reward system hot spots. But if you eat that same dish many days in a row, dopamine levels will spike less and less, eventually leveling out. 

Thats because when it comes to food, the brain evolved to pay special attention to new or different tastes.

Why?

Two reasons: 

First to detect food thats gone bad. And second because the more variety we have in our diet, the more likely we are to get all the nutrients we need. To keep the variety up, we need to be able to recognize a new food, and more importantly we need to want keep eating new foods.

And thats why the dopamine levels off when a food becomes boring. Now back to that meal. What happens if in place of the healthy balanced dish, you eat sugar rich food instead?

If you are really eat sugar or dont eat much at a time, the effect is similar to that of the balanced meal. But if you eat too much the dopamine response does not level out.

In other words eating lots of sugar will continue to feel rewarding. In this way sugar behaves a little bit like a drug. Its one reason people seem to be hooked on sugary foods.

So think back to all those different kinds of sugar. Each one is unique but every time any sugar is consumed, it kickstarts a domino effect in the brain that sparks a rewarding feeling.

Too much too often and things can go into overdrive. So yes overconsumption of sugar can have addictive effects on the brain, but a wedge of cake once in a while wont hurt you.