What Sugar Does To Your Brain?

What is the correlation between sugar and brain function? It turns out that this relationship, like any relationship, has it’s good points and it’s bad points. Have you ever felt the excitement and agitation of a sugar buzz? And then the lethargy of a sugar crash? Your brain needs some sugar to function, yet too much sugar can be harmful. We all love to have those sweets but must learn to enjoy them in moderation.Overeating, poor memory formation, learning disorders, depression—all have been linked in recent research to the over-consumption of sugar. And these linkages point to a problem that is only beginning to be better understood: what our chronic intake of added sugar is doing to our brains.

According to USDA,  the average American consumes 156 pounds of added sugar per year. That’s five grocery store shelves loaded with 30 or so one pound bags of sugar each. If you find that hard to believe, that’s probably because sugar is so ubiquitous in our diets that most of us have no idea how much we’re consuming. The Centers for Disease Control (CDC) puts the amount at 27.5 teaspoons of sugar a day per capita, which translates to 440 calories—nearly one quarter of a typical 2000 calorie a day diet.The key word in all of the stats is “added.” While a healthy diet would contain a significant amount of naturally occurring sugar (in fruits and grains, for example), the problem is that we’re chronically consuming much more added sugar in processed foods, generally in the rapidly absorbed form of fructose.


Glucose is a form of sugar that your body creates from the carbohydrates you eat. Once the glucose is made it gets into the bloodstream so that your muscles and organs can use it for energy. In fact, your brain needs at least 125 to 150 grams of glucose per day to function. It’s usually the only source of energy for the brain. The brain’s neurons must have this supply of energy from the bloodstream since they aren’t capable of storing energy, like fat, for later use.

But not all sugar is equal. There are different forms of sugar that your body uses for energy, some more harmful than others. The brain needs a steady supply of energy that will last until more energy comes along. Spikes in this supply are dangerous and cause things such as hyperactivity and ‘sugar crashes’. The sugar from fruit will get into the bloodstream at a steady rate as the fruits digests in the stomach. Fruits also provide great sources of vitamins, minerals and fiber, so fruit sources of sugar are great for the brain and your body.

Complex carbohydrates such as starch also break down in the liver to form sugar. These strands of energy take a longer amount of time to break down, so this source of sugar works well with the brain in much the same way as fruit. They can provide energy for hours without diminishing. One thing to think about though about complex carbohydrates is that they contain appetite enhancers and so tend to cause people to overeat, unlike fruit.

Refined sugars and brain function are a big no-no. These are the sugars we typically find in abundance on store shelves and in the average North American diet. The sugar energy from soda, cookies and desserts, flood your bloodstream with glucose almost immediately. At first you get an initial ‘sugar high’ as the sugar queues serotonin, a brain chemical that makes you feel happy, to be released into the brain. The massive increase in blood sugar signals the pancreas to start pumping out large amounts of insulin. Once the insulin gets into the bloodstream it soaks up the sugar to store for later use, depriving the brain, other organs and muscles of energy. These are the beginnings of the infamous ‘sugar crash’ as you become weak, tired and unable to focus. The ‘sugar high’ combined with the ensuing ‘sugar crash’ causes you to crave even more sugar, most likely resulting in a damaging cycle of sugar binging. So avoid refined sources of sugar as much as possible.

David DiSalvo of Psycholgy Today writes that Research indicates that a diet high in added sugar reduces the production of a brain chemical known as brain-derived neurotrophic factor (BDNF). Without BDNF, our brains can’t form new memories and we can’t learn (or remember) much of anything. Levels of BDNF are particularly low in people with an impaired glucose metabolism—diabetics and pre-diabetics—and as the amount of BDNF decreases, sugar metabolism worsens.

In other words, chronically eating added sugar reduces BDNF, and then the lowered levels of the brain chemical begin contributing to insulin resistance, which leads to type 2 diabetes and metabolic syndrome, which eventually leads to a host of other health problems. Once that happens, your brain and body are in a destructive cycle that’s difficult if not impossible to reverse.

Another connection between sugar and brain function concerns dysfunction. People who regularly eat too much sugar over a long period of time often become diabetic. These people often have dwindling mental capabilities. They are more at risk to develop depression and different cognitive problems with memory, processing information and recognizing spatial patterns. It can even lead to dementia. Also, people who suffer from diabetes have a 65% higher incidence of Alzheimer’s disease than those who are not diabetic.
Research has also linked low BDNF levels to depression and “Psychology Today looks at Dementia” dementia. It’s possible that low BDNF may turn out to be the smoking gun in these and other diseases, like “Psychology Today looks at Alzheimer’s Disease”

Alzheimer’s, that tend to appear in clusters in epidemiological studies. More research is being conducted on this subject, but what seems clear in any case is that a reduced level of BDNF is bad news for our brains, and chronic sugar consumption is one of the worst inhibitory culprits.

Other studies have focused on sugar’s role in over-eating. We intuitively know that sugar and obesity are linked (since sugar is full of calories), but the exact reason why eating sugar-laden foods seems to make us want to eat more hasn’t been well understood until recently.

New research has shown that chronic consumption of added sugar dulls the brain’s mechanism for telling you to stop eating. It does so by reducing activity in the brain’s anorexigenic oxytocin system, which is responsible for throwing up the red “full” flag that prevents you from gorging. When oxytocin cells in the brain are blunted by over-consumption of sugar, the flag doesn’t work correctly and you start asking for seconds and thirds, and seeking out snacks at midnight.

What these and other studies strongly suggest is that most of us are seriously damaging ourselves with processed foods high in added sugar, and the damage begins with our brains. Seen in this light, chronic added-sugar consumption is no less a problem than smoking or alcoholsm. And the hard truth is that we may have only begun to see the effects of what the endless sugar avalanche is doing to us.

Manufacturers today put sugar in everything from the bread in your pantry to the turkey on your table. That makes sweet ol’ sugar the ultimate supervillain—or at the very least a driving force behind heart disease and diabetes.




Asian sauces—or at least American versions of Asian sauces—are notorious sources of hidden sugars. The viscous liquids that give us sesame chicken, sweet and sour pork, and beef teriyaki aren’t all that dissimilar from pancake syrup. Check the nutrition label for ingredients like corn syrup and high-fructose corn syrup, and watch out for anything that ends in “-ose” (dextrose, maltose). These are all forms of sugar. Then be prepared to do some math—most bottled sauces list nutrition information for impractically small serving sizes. Who uses only 1 tablespoon of sauce?


Jams, jellies, and preserves seem like healthy breakfast alternatives to butter and cream cheese—and they are if they contain only fruit. But many fruity toppings house a shocking amount of added sugar. Smucker’s, for instance, packs three different sweeteners into its classic Strawberry jam. Why three? Because if the company used only one, it would have to list “sugar” as the first item on the ingredient statement. By spreading the impact over three sweeteners, it can push fruit to the top of the ingredient list and hide the sweeteners below. It’s a common trick used by food processors to make their products look healthier than they are. Just remember that fruit is its own natural sweetener. Opt for an unadulterated version like Polaner’s All Fruit spreads, which—true to name—contain nothing more than fruit and fruit juice.



You may not be aware of that salad saboteur lurking in your pantry. When the so-called “light” dressings take out fat, they often add sugar in its place. Take Ken’s Sun-Dried Tomato Vinaigrette, pictured here. It contains as much sugar in each serving as some ice creams do in each scoop. And what’s worse, it’s laced with food starch. Although technically not sugar, it reacts in your body in almost exactly the same way. That means that in addition to the 12 grams of sugar on the label, you’re also taking in a heavy dose of blood-sugar-spiking starch. Let’s call this dressing what it really is: salad frosting.



There’s no need to add sugar to tomato sauce because tomatoes are naturally sweet. So why do processors insist? Because instead of using fresh olive oil and vegetables, they’re often making their sauces from cheaper vegetable oils, dehydrated veggies, and other subpar ingredients. Sugar is a quick fix: It makes everything taste like candy! To that point, Francesco Rinaldi lists sugar as the second ingredient in this sauce, which brings the total impact to nearly 3 teaspoons of sugar in each serving. Your best bet? Go with a no-sugar-added option like Ragu’s Tomato Basil. It contains just tomatoes, onions, and spices. And be sure to also look out for the sugar count of barbecue sauces—another tomato-based sauce notorious for sneaky sweeteners.


Oats have been linked to heart health, weight loss, and cancer prevention, so it’s natural to assume that oatmeal is always a nutritious breakfast choice. But many food producers spoil the whole-grain goodness by flavoring their oats with artificial ingredients and loads of sugar. Quaker’s Cinnamon Roll Oatmeal Express, for example, takes its name very seriously—it contains as much sugar as two Pillsbury cinnamon rolls! A touch of sugar is one thing, but unless you want to eat dessert for breakfast, go with a lower-sugar option. Or better yet, make your oatmeal from scratch so you can control the sugar load. (Tip: Berries are the perfect way to sweeten naturally.



Studies have shown that whole grains improve your heart health, keep you full, and help you lose weight, but not all bread products labeled “wheat” are true whole grains. Restaurants and supermarket aisles are rife with whole-wheat imposters containing enriched flours and sugars intended to improve the taste of wheat products. So even though you don’t typically file bread under the “sweets” category, your daily sandwich could be loaded with refined carbs and sugars. The best example of the whole-wheat bait-and-switch is the “Honey Wheat” bread Arby’s uses on its Market Fresh sandwiches. First, it’s not whole wheat (enriched flour is the first ingredient). And second, there are 15 grams (!) of sugar in every two slices. That’s more sugar than you’ll find in a Hostess Ho Ho!


Yogurt is low in calories and high in protein, which is why a recent Harvard study found that regularly consuming the stuff helps you lose weight. The problem? Many producers pump their “fruit flavored” yogurts with sugar. Case in point: The cups in Yoplait’s Original 99% Fat Free line pack as much sugar as a bag of peanut M&M’s. Unless yogurt is your weekly diet splurge, go with a less dessert-y option like Dannon Light & Fit, or opt for plain yogurt and add your own healthy toppings like fresh fruit and nuts.



The idea of a frozen meal packed in a nuke-able box probably doesn’t get your taste buds giddy with anticipation. Food manufacturers are aware of this fact, so they go heavy on the sugar and/or salt. Some of the worst offenders? Low-cal or otherwise “light” entrées. When food companies remove fat or carbs from their items, they usually replace those calories with excessive doses of sugar or sodium. Take Lean Cuisine’s Roasted Turkey Breast entrée, for example. Chances are you don’t think of turkey as dessert, but with 7 teaspoons of sugar, that’s exactly what you’re getting if you pop one of these babies in the microwave. Again, it’s all in the nutrition label. Don’t just focus on fat and calories; make sure to look out for sneaky sugars and sodium as well.


In recent years, tea has received a lot of good press for its impressive antioxidant properties, and beverage companies have taken advantage by flooding the market with options. But the taste of plain herbal tea doesn’t draw in the crowds, so many drink purveyors pump their teas with high-fructose corn syrup and other cheap sweeteners to boost flavor. Before you buy a bottle, flip it over and read the nutrition label. If you’re looking at Arizona’s Green Tea, you’ll notice that it has more sugar than a Snicker’s bar.