“Dis moi ce que tu manges, je te dirai qui tu es,” (Tell me what you eat, and I will tell you who you are) wrote the French culinary philosopher Jean Brillat-Savarin in 1848. With modern science, we can now change that to “Tell me what you eat, and I will tell you how you think.” We’ve known for a long time that there’s a direct link between diet and physical health (in fact, Brillat-Savarin was one of the first to recognize that too much sugar and starch leads to weight gain). Now, however, there’s increasing evidence that your diet has an immediate, and often negative, impact on how your brain works – and therefore how well you’re able to think and remember.

For example, a recent study done by researchers and scientists at UCLA found that eating too much fructose can actually slow down the function of your brain. Fructose is a naturally-occurring sugar found in honey, fruits (fructose means “fruit sugar”), berries, and sweet root vegetables such as carrots and beets, and in general you won’t have a problem getting too much of it if you’re eating a healthy diet rich in fiber, fresh produce, and healthy proteins. Unfortunately, many of the processed foods sold in the United States and around the world have fructose added to them to enhance taste and/or appearance. And you’ve probably heard about “high fructose corn syrup,” a chemical compound that’s often the first ingredient in soda, condiments, or breakfast cereal, among many other food items. All of these non-natural foods, when eaten over the course of several weeks, deliver a large dose of fructose to your body and brain.

In a study involving lab rats, Professor Fernando Gomez-Pinilla discovered that the rats who were fed diets high in fructose were unable to remember the paths through mazes, even when the mazes contained obvious markers to help the rats trace their paths. The rats without the added fructose in their diets were able to use these markers to help them remember. Dr. Gomez-Pinilla emphasized in his report that the effects of high fructose consumption were obvious after only six weeks. Think about all of the sugary energy drinks the typical university student drinks in an effort to keep their brain charged, and you’ll soon realize that such a student is in fact getting the opposite result!

Dr. Gomez-Pinilla also discovered that including omega-3 fatty acids (such as those found in oily fish and flaxseed) counteracts some of the effects of fructose. While it’s a good idea to include those good supplements in your diet, it makes the most sense to avoid the high levels of fructose in processed food in the first place, so that you don’t run the risk of slowing your brain down and losing your memory.