It is no secret that glucose, a form of sugar, is the main source of energy for every cell in our bodies, including our brain cells. Because the brain is packed with neurons, it uses more energy than any other organ in the body.
Our brains reward us for consuming sugar. Whether you are eating a delicious meal, sharing a kiss with someone you love, or enjoying a sugary treat, the mesolimbic dopamine system activates, releasing dopamine (a feel-good brain chemical) and reinforcing that behavior.
While our brains depend on sugar to function properly, too much of this fuel can be detrimental to brain health. Below, we break down how sugar impacts the brain, including its effect on cognitive function, mood, and disease risk.
Even if you don't have a sweet tooth, you might be consuming significantly more sugar than you think, particularly if your diet includes a lot of processed foods. Sugar is one of the most common ingredients in processed foods. The average American adult, teenager, and child consume about 17 teaspoons of added sugar per day, which is well over the amount recommended by the American Heart Association—no more than 6 teaspoons (25 grams) and 9 teaspoons (36 grams) per day for most adult women and men, respectively.
With that in mind, let’s take a look at how sugar impacts the brain.
Brain functions, such as thinking, memory, and learning, are closely linked to glucose levels. When glucose levels are low, such as with hypoglycemia, the lack of energy for brain function can cause poor cognitive function. When glucose levels are high over a prolonged period, such as with diabetes, the brain’s functional connectivity is affected, and the brain volume can reduce (atrophy). High blood glucose levels can also damage blood vessels in the brain, restricting blood flow. This restricted blood flow can cause cognitive impairment or even lead to the development of vascular dementia.
A 2016 study found that high sugar consumption may cause neuroinflammation (inflammation in the brain) in regions of the brain that are crucial for memory. A 2017 study found that a higher intake of sugary beverages was associated with lower total brain volume and poorer performance on tests of episodic memory. They also found that daily fruit juice intake was associated with lower total brain volume, hippocampal volume, and poorer episodic memory. This implies that excess sugar consumption was associated cross-sectionally with markers of preclinical Alzheimer’s disease.
While sugar consumption may boost your mood momentarily, high sugar consumption has been linked to poor emotional regulation and an increased risk of mental health problems. As we mentioned before, sugar consumption affects the mesolimbic dopamine system. Because this system influences emotion and behavior, sugar consumption can impact our mental health and behavior.
A 2017 study of 23,245 individuals found that men who consumed the most sugar were 23% more likely to be diagnosed with a mental disorder after five years compared to those who consumed the least sugar.
High-sugar diets have long been associated with health problems such as diabetes, heart disease, and obesity. However, many people don’t know that these conditions are also risk factors for Alzheimer’s disease and other causes of dementia. Research suggests that a high-fat, high-sugar diet is associated with greater risk and earlier onset of Alzheimer’s disease, whereas a low-sugar diet high in unsaturated fats, fiber, and protein is associated with lower rates of Alzheimer’s disease.
Like most things, sugar can be okay in moderation. We all deserve a sweet treat every now and again, but we should also be observant and mindful of what we are putting into our bodies. Here are some helpful tips to help manage your sugar intake:
Aside from cutting down your sugar intake, there is plenty you can do to maintain a healthy brain, including:
It is never too early—or too late—to make changes to your lifestyle and understand and monitor your brain health.
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