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How Does Sugar Affect the Brain?

by Aviv Clinics
June 13, 2021

From the Paleo diet, to the Mediterranean diet, to the ketogenic diet, to DASH and beyond, there’s one thing that nearly all modern diets agree on — if you want to maintain a healthy body and mind, cut out sugar. While there is wisdom to be found in this advice, blanket statements like “cut out sugar” can leave room for confusion. It leaves many people wondering, is all sugar bad for you? Should you avoid sugar in any form, including in fruits? What about carbohydrates found in vegetables like potatoes?

With so many complicated questions like these and no clear answers to be found, it’s no wonder that so many people feel confused. As a center dedicated to improving brain health and performance, Aviv Clinics understands the importance of proper nutrition and its direct effect on cognitive and physical functioning. It’s worth examining sugar in detail, and clarifying what dietitians really mean when they tell you to cut out sugar.

Is sugar really the enemy?

Foods that contain high amounts of sugar can still be healthy! Apples contain lots of sugar, but they also contain water, vitamins, nutrients, and dietary fibers that are vital for a healthy body. Dietary fiber is especially important for maintaining a thriving wealth of gut flora, which builds our immune system and fights off ailments like leaky gut disease.

Besides fruits, natural sugars are found in many different whole foods. They also come in many different chemical forms, including glucose from carbohydrates. Glucose provides our bodies with energy, helping fuel our muscles and vital organs as it circulates throughout the bloodstream. We depend on the glucose that comes from carbohydrates and we wouldn’t be able to function normally without it.

At the end of the day, any leftover glucose in our bloodstream gets processed into glycogen by the liver and put into storage in our fat reserves. Our bodies can then re-convert that stored glycogen back into glucose when blood sugar levels are low and we need to burn extra energy. It’s just one of our body’s numerous survival mechanisms ensuring that we’ll always have glucose to draw on, even when food supplies are low.

Does your brain need sugar?

Although the brain can use alternative fuel sources for fuel if you’re insulin resistant, such as ketones, glucose is the brain’s preferred fuel source. The brain relies heavily on glucose when performing complex tasks that require a lot of thought. Experiments in both animals and people have revealed that when the brain needs an extra boost of power, blood vessels in the brain dilate to deliver more glucose and oxygen through the bloodstream. So when you’re concentrating extra hard on a crossword puzzle or a complicated passage in your favorite book, your brain is burning glucose on overtime to help you get the job done. If your blood sugar dips too low, you can experience problems like brain fog or trouble concentrating. It’s your brain’s way of telling you that it needs more fuel and that you need to grab a healthy snack.

While getting adequate glucose through your diet is paramount for a healthy brain, it is possible to have “too much of a good thing”. Modern western diets are filled with refined sugar and carbohydrates in the form of ready-made snacks, treats, and processed foods. There’s a difference between consuming natural sugars found in fruits and vegetables and consuming the added sugar in processed foods.

What is the difference between natural sugar and refined sugar?

When you eat an apple, your body does all the work of processing the unrefined fruit into digestible nutrients all on its own. First, you have to chew the apple, breaking it down into apple sauce. Then, your gut does the hard work of absorbing the vital nutrients and breaking down the sugar to send circulating throughout your bloodstream, and the leftover fiber is used to nourish your gut’s network of microflora. When you eat whole foods, your body is the factory, and the natural sugars in your foods are the fuel that runs it.

However, processed foods are a different story. Candies, cookies, chips and other pre-packaged snacks don’t offer your body the same kind of fuel as whole foods. Your body doesn’t have to go through the work of breaking these highly processed foods down — it’s already been done for you at a factory.

These kinds of foods are loaded with refined sugar without any of the nutrients, vitamins and fibers your body needs. This leaves your gut flora starved of the materials they need to function and your immune system vulnerable. You may end up feeling sluggish once the “sugar high” wears off. Eating excess amounts of sugar can also make you susceptible to health conditions like type 2 diabetes.

How does excess sugar affect the brain?

Eating foods high in refined sugar can also impact your cognitive performance. When rats were fed a high-sugar diet that resembles the average western diet, their cognitive performance suffered. The rats struggled to complete tasks that relied on their memory, suggesting that their diets were directly responsible for impairing the prefrontal lobe and hippocampus regions of their brains.

Further research echoes this idea. Eating a diet high in sugar can reduce the production of a chemical called “brain-derived neurotrophic factor” (BDNF). This chemical is active in areas of the brain that are vital to learning, memory and higher thinking. Low BNDF levels are associated with poor memory function and have been linked with Alzheimer’s Disease and dementia. It’s clear that a diet high in refined sugar can directly impact your brain function.

Tips for healthy eating

The natural sugars found in whole foods are nothing to be afraid of. Eating a diet that contains enough carbohydrates and natural sugars is important for keeping your body and brain healthy. Here are a few ways to stay on track:

  1. Make sure the bulk of the sugar you consume comes from whole foods like fruits and vegetables, not processed junk foods.
  2. Just because a food is labeled “sugar-free,” that’s not always the case. It may be true that a food doesn’t contain added sugar, but remember that carbohydrates turn to glucose in your body.
  3. You can rack up carbohydrates quickly on a typical day. Try to aim for around 45 total carbs at every meal if you’re a woman, or 60 every meal if you’re a man. You’ll be surprised how quickly you can meet that quota with just a handful of whole foods!
  4. You don’t have to cut out refined sugar altogether. Obsessing over eating a “perfect” diet only stresses you out, and it doesn’t leave any room for you to feed your soul. Spending a relaxing afternoon baking with your grandkids? Go ahead and treat yourself to a warm cookie fresh from the oven.
  5. If you’re eating healthy at most meals, there’s no need to feel guilty about indulging in rich foods every now and then. Just be smart about it, and always make conscious decisions about what kind of foods you put into your body.

Aviv Medical Program provides you with a unique opportunity to invest in your health while you age