Effects of diets rich in fructose on our brain

Hi, my name is Julia Jarosławska and I am going to tell you what effect does fructose have on our brain. Sugar is becoming the leading ingredient in the contemporary diet and is readily

available in many forms: from chocolates through ice creams to soft drinks and flavored coffee. And sugar is not only in sweets and desserts. It is also added to ketchup, dairy products, bread, salad dressing and breakfast cereals. If you check the nutrition labels on the products you buy, you will find sugar

hidden under a number of names: glucose, sucrose, dextrose, maltose, fruit juice extract, raw sugar, palm sugar, corn syrup, starch, honey and many others - these are all forms of sugar. One could think that sugar is sugar, but actually some sugars are better for us than others. One of the examples of a sugar that is damaging for our health when consumed in excess is fructose. Fructose is naturally occurring in fresh fruits and some vegetables. However, most of fructose intake in our diet originates from “table sugar” sucrose, containing 50% of glucose and 50% of fructose, and soft drinks containing high fructose corn syrup (HFCS).

High fructose corn syrup is a sweetener made from processed cornstarch and, similarly to sucrose, it is a combination of glucose and fructose, but in variable proportions. Its flavor is similar to sucrose, but it is 1.5 times sweeter and cheaper to produce. As a result, you can find high fructose corn syrup in just about anything. Although glucose and fructose are both simple carbohydrates with the same chemical composition of carbohydrate and oxygen, they have different structures and behave quite differently in our bodies. Glucose is the best source of energy for nearly all organisms on earth and it can be metabolized by all organs in the body.

Fructose, on the other hand, is metabolized primarily in the liver, and when the liver is overloaded with sweet fructose, the excess is metabolized to fat. In fact, up until the last few decades, our diet contained only a small amount of fructose from natural sources like fruits. In addition to lower concentration of fructose, fruits contain water, vitamins, fiber as well as many antioxidants and minerals. Fructose in fruits does not cause overload, because the fiber in fruits slows down its absorption and the liver has the time to deal with fructose. On the other hand, high fructose corn syrup adds an unnatural amount of fructose to our diet. It contains plenty of calories, but absolutely no essential nutrients.

While the effect of the diet high in simple carbohydrates, and more specifically a high-fructose diet, has been established as negatively influencing body weight and metabolism, much less is known about the corresponding effects on brain. Animal studies are being used to study how sugars affect brain functioning and physiology. Interestingly, in the brain, fructose appears to promote feeding behavior. Fructose may be a weaker suppressor of appetite. Unlike glucose, fructose does not stimulate pancreas to secrete insulin, a hormone that signals the brain to increase satiety and to blunt the reward value of food. Additionally, fructose fails to suppress levels of the appetite stimulating the ghrelin hormone.

And, relative to glucose, consumption of fructose produces smaller increases in the circulating satiety hormones such as GLP-1 and leptin. What is more, fructose has a sweeter taste than glucose, and the sweet taste is known to activate brain pathways involved in the reward and motivation. Current research suggest that an excessive fructose intake may lead to impaired cognitive functions and memory deficiency. Rats consuming high fructose corn syrup performed poorly in an experiment in which they were learning how to navigate and escape the maze. The effect of fructose on cognition seems to be agedependent, since the impairment of memorization process was particularly noticeable in the adolescent rats. As it turns out, fructose is not that sweet.

Besides causing weight gain and metabolic abnormalities, a diet high in fructose may also negatively impact mental performance and increase appetite. Therefore, a good strategy for a healthy nutrition would be to cut down on sugar, eat less processed foods and check the ingredients tables.