The Impact of Sugar on the Brain – Addiction and Cognitive Impairment

The Impact of Sugar on the Brain

Everyone knows that too much sugar in your diet is bad for your health, causing excess weight gain and increasing* your risk of diabetes, cardiovascular disease, and even cancer. But a growing body of research is now finding that sugar can be just as damaging to your brain, causing cognitive impairment and possibly mental health problems. As it turns out, your brain on sugar is similar to the brains of those addicted to cocaine which explains why some of us experience sugar cravings. But other than sugar addiction, other consequences of a diet too high in sugar include impaired memory, depression, anxiety, and Alzheimer’s disease.

What is sugar anyway?

When speaking of sugar, most tend to associate the word with the white crystalline powder we use to make our desserts taste sweeter. But sugar, in its broadest definition, is a type of carbohydrate naturally found in foods like fruits, honey, and milk. These are classified according to their molecular structure into glucose, fructose, lactose, maltose, and sucrose. A narrower classification of carbohydrates is into simple and complex with complex carbs considered to be good for our health. Simple carbohydrates like sucrose found in sugar and fructose found in corn syrup are generally considered bad for your health and your daily intake of these sugars should not exceed 30g according to the NHS.

Why Your Brain Craves Sugar?

But a bit of sugar is good and even necessary for your health. Your body converts carbohydrates into glucose which is the main fuel for your cells. Interestingly, your brain requires more sugar than any other organ in the body, which is probably why sugar can trigger addictive behavior since the brain essentially runs on sugar. As explained in a 2014 issue of Trends in Neuroscience, in humans, the brain accounts for only 2% of total body weight but consumed 20% of the body’s glucose stores. Glucose is required for neurotransmitter synthesis and in the brain’s cell energy generation. As a result, any disruption in glucose metabolism is bound to show on your brain health. One way this could happen is by eating too much of the bad kinds of sugars.

Impact of Sugar on the Brain

Too Much Sugar and Brain Health

People who eat too much refined sugar and carbohydrates and who don’t exercise regularly are at a higher risk of developing diabetes. Diabetes is characterized by high blood sugar levels over a prolonged period of time because the body fails to metabolize glucose due to low insulin production. The result of this is less glucose feeding the brain and this is known to be damaging to the brain. A study published in Diabetes & Metabolism, the brain can be damaged by all types of diabetes being a glucose-dependent organ. This was made evident by brain imaging showing structural changes to the brain caused by diabetes as well as the high prevalence of co-morbid psychiatric disorders.

Sugar Causes Addiction

But sugar can cause damage to the brain long before it affects your glucose metabolism. According to the latest research, sugar can cause addiction because it leads to dopamine and opioids being released in the brain. While these chemicals make you feel good initially, once their levels in the brain drop (which inevitably happens), anxiety and depression set in. This was confirmed in a study published in Neuroscience & Behavioral Reviews that found four components of addiction in mice fed a high sugar diet. The mice exhibited bingeing, craving, and withdrawal symptoms due to such a diet and their brains showed definitive signs of addiction. Furthermore, a review published in the Current Opinion in Clinical Nutrition and Metabolic Care states that the sweet reward of sugar consumption is sufficient to explain why so many people today find it difficult to control sugar cravings.

Sugar and Cognitive Impairment

And while your sugar addiction is probably making your miserable now, forcing you to rely on chocolate bars in order to feel good, the long-term consequences of sugar consumption are even scarier. One study found that high glucose levels which are frequently seen in people who eat a carbohydrate-rich diet are strongly associated with a higher risk of dementia and Alzheimer’s disease, regardless of the presence or absence of diabetes. A different study even found that having type 2 diabetes is a risk factor for Alzheimer’s disease and this metabolic derangement was linked to a diet too high in fructose or sucrose.


Modern diets are often too high in sugar while being low in other nutrients such as fiber, vitamins, minerals, and protein. The most visible consequence of such diets is excess weight gain, but newer studies also link these diets to cognitive impairment and the risk of neurodegenerative diseases such as Alzheimer’s. In addition to this, reducing* your sugar intake can be tough given that sugar is the type of food most likely to cause addiction. Later on, sugar addiction can lead to depression and anxiety due to the shifting in feel-good hormones in the brain. However, limiting your sugar intake is important not just for your brain and mental health, but your overall health as well.

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Contributor : Dr. Ahmed Zayed (Consumer Health Digest)

Dr. Ahmed Zayed Helmy holds a baccalaureate of Medicine and Surgery. He has completed his degree in 2011 at the University of Alexandria, Egypt. Dr. Ahmed believes in providing knowledgeable information to readers. Other than his passion for writing, currently he is working as a Plastic surgeon and is doing his masters at Ain Shams University. You can connect with him on Linkedin.

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