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February 16, 2023

mbg Health Contributor

By Jenny Fant

mbg Health Contributor

Jenny is a San Francisco-based mbg contributor, content designer, and climate & sustainability communications specialist. She is a graduate of the University of California Santa Barbara. An avid open-water swimmer, Jenny has worked for healthy living and nutrition brands like Sun Basket, Gather Around Nutrition, and Territory Foods.

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February 16, 2023

Alzheimer’s disease remains a major health concern, with nearly 6 million1 people estimated to be living with it. A recently published narrative review presents the theory that fructose, a common sugar found in fruits and packaged food across the globe, might lead to the development of the disease.

A recent narrative review2 published in the American Journal of Clinical Nutrition explores how the relationship between fructose and humans’ ancient foraging instincts might be to blame for the onset of Alzheimer’s disease (AD).

Lead author Richard Johnson, M.D., theorizes that because humans evolved to sometimes be quick-thinking risk-takers in the pursuit of food, fructose may actually enhance that instinct by getting in the way of our memory centers and attention to how much time has passed. 

In other words, a human with less regard for time and recent memory may be more likely to forage for food more quickly and effectively, tending to ignore risk or other distracting factors.

But as with anything, too much of a good thing can lead to unintended problems.

“We hypothesized that the fructose-dependent reduction in cerebral metabolism in these regions was initially reversible and meant to be beneficial,” Johnson wrote. “However, the chronic and persistent decrease in cerebral metabolism driven by recurrent fructose metabolism leads to progressive brain atrophy and neuron loss with all of the features of AD.”

So, this once-lifesaving brain function may be firing too often in the modern brain and leading to permanent damage, leading to diagnoses like AD.

Scientists noted that wandering off—a common symptom of AD—may even be linked to the foraging instinct promoted in early humans.

It’s clear that a diet too high in sugar is bad for overall health and longevity. And while this review explores why fructose might lead to AD specifically, there are plenty of reasons to limit your sugar intake and consider alternatives.

Fructose, sometimes referred to as fruit sugar, can be found in many foods these days. While fruit is nutrient-dense and healthy in moderation, other common sources of fructose are not. Take high-fructose corn syrup: Made from corn, it shows up all over grocery aisles and presents a long list of negative health effects—including potentially harming brain function3, according to animal research.

We know that too much fructose or sugar of any kind can also have lasting health effects beyond AD, such as obesity, diabetes, inflammation, and high blood pressure.

Science just got closer to explaining why excessive sugar intake could lead to cognitive decline and diseases like AD. In line with a wealth of research telling us to avoid consuming too much sugar, this review is a good reminder to focus on healthy habits and moderate your intake of sugar and processed foods.

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