What does sugar do to the brain?

Glucose is the primary fuel for the human brain, but what happens when the brain is exposed to the excessive added sugars of the standard American diet?

Elevated blood glucose damages blood vessels, and this blood vessel damage is the major cause of vascular diabetes complications, such as retinopathy. The vessels in the brain can also become damaged by elevated blood glucose and there is evidence that this damage contributes to a progressive decline in brain function. Studies on those who have lived with diabetes for many years have found deficits in learning, memory, motor speed, and other cognitive functions. Frequent exposure to high glucose levels likely diminishes mental capacity, as higher HbA1C levels have been associated with a greater degree of brain shrinkage. Even in those without diabetes, higher sugar consumption is associated with lower scores on tests of cognitive function. These effects are thought to be due to a combination of not just the episodic high blood glucose, but also the metabolic effects on cholesterol, fat storage and blood vessel disease that results. It is not surprising that higher blood sugars increase the risk of Alzheimer’s Disease, and that Alzheimer’s has even been called “type 3 diabetes.”

Sugar’s harmful effects on the brain don’t only occur in the long term; even a single and episodic instances of high blood sugar can slow cognitive function and lead to deficits in attention and memory. Excess sweets can also affects your mood. Eating commercial sweets and baked goods are linked to higher rates of major depression. Brain imaging suggests that high glucose levels impairs the brain’s ability to process emotion, even in healthy young people.

In addition to the damaging effects on cognition and mood, sugar also has drug-like effects in the reward system of the brain. Our physical and hormonal satiety signals seem to be overwhelmed by the unnatural concentrations of such concentrated sweeteners.

The ability of sugar to produce a powerful reward response was demonstrated by a study in which rats were allowed to choose between pressing two levers: one lever gave them access to sugar-sweetened water, and the other a dose of intravenous cocaine. The rats preferred sugar over cocaine. In humans, high-glycemic foods have been found to activate regions of the brain associated with the same reward response as illegal drugs. They produce an intense desire to overeat.

It is not easy to rid oneself of their desire for sweets. It takes knowledge and experience to help people with the nutritional tips and emotional techniques to beat sugar addiction, and take back control of their health. My book, The End of Dieting focuses on the factors most effective to recover from food addiction, emotional eating and keep the weight off forever. 

Remember, added sugar is a dangerous food, and the only way to avoid these dangers by enjoying sweet, delicious dried and fresh fruits in place of refined sugars, in recipes and deserts. You won’t sacrifice enjoyment of food, even sweet desserts can be healthful when you learn the innovative cooking techniques using only dried and fresh fruits to make healthy food taste great.

Dr. Fuhrman is a #1 New York Times best-selling author and a board certified family physician specializing in lifestyle and nutritional medicine. The Eat To Live Cookbook offers over 200 unique disease-fighting delicious recipes and his newest book, The End of Heart Disease, offers a detailed plan to prevent and reverse heart disease using a nutrient-dense, plant-rich eating style. Visit his informative website at DrFuhrman.com. Submit your questions and comments about this column directly to [email protected] The full reference list for this article can be found at DrFuhrman.com.