Does the Sweetener Fructose Cause Memory Problems?

The sweetener fructose has been under fire recently with reports that it contributes to heart disease and the rate of obesity in this country. Now, there’s new evidence that, at least in rats, the effects of fructose may include memory related problems, particularly problems with spatial memory tasks.

Fructose Effects on Spatial Memory Tasks: The Study

In this study, published in the journal Neurobiology of Learning and Memory, researchers found that rats that were given a diet containing sixty percent fructose performed more poorly on memory tasks, particularly those that involved spatial memory. Although fructose didn’t seem to affect the rats’ ability to learn a new task, it made it more difficult for them to complete a task successfully due to memory related issues.

Fructose Effects in Humans?

It’s not clear whether these same fructose effects would be seen in humans, but it adds to the growing body of literature pointing to the negative health risks of using fructose as a sweetener. Fructose appears to increase the risk of heart disease by raising levels of triglycerides and LDL cholesterol and has been associated with a higher rate of obesity and type 2 diabetes. It’s also difficult for many people to digest fructose which can lead to abdominal bloating and cramping. Although fructose is found naturally in fruits, it doesn’t appear to have the same adverse effects when consumed in this form, probably because the high fiber content of the fruit moderates the blood sugar response.

Problems With Memory Loss?

Why would fructose cause problems with completion of spatial memory tasks in rats? Fructose appears to increase insulin resistance making it more difficult for the body to use insulin it makes. A study done in hamsters showed that insulin resistance can affect the function of a part of the brain known as the hippocampus. This portion of the brain is involved in long term memory and spatial memory which could explain the difficulties the rats encountered with spatial memory tasks after eating a high fructose diet.

Fructose Effects: How Common Is It?

Unfortunately, most Americans, often unknowingly, consume a diet high in fructose. This sugar is used to sweeten a variety of beverages and packaged foods. Manufacturers find this sweetener to be appealing due to its low cost and its higher relative sweetness compared to table sugar or honey. Table sugar is made up of equal parts of both fructose and glucose, but is metabolized differently than straight fructose. Table sugar is normally metabolized by the liver before it enters the bloodstream and becomes available to cells whereas fructose can enter cells directly without the need for processing by the liver or the release of insulin.

Fructose Effects: The Bottom Line?

Whether or not fructose affects spatial memory in humans is unknown, but with increasing evidence of the negative effects of fructose, it’s probably best to avoid this common sweetener.