How fructose changes the brain

Christiane Fux studied journalism and psychology in Hamburg. The experienced medical editor has been writing magazine articles, news and factual texts on all conceivable health topics since 2001. In addition to her work for, Christiane Fux is also active in prose. Her first crime novel was published in 2012, and she also writes, designs and publishes her own crime plays.

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Too much fructose can apparently reduce the performance of the brain. Nevertheless, it is added to many foods because of its great sweetening power. But there is an antidote: fish.

Yogurt and lemonade, cake and ice cream, ketchup and ready meals - fructose is not only found in fruits. The type of sugar is particularly sweet - and particularly cheap, which is why it is used on a large scale in the food industry. This is problematic because when consumed in large amounts, fructose, which comes from actually healthy fruits or corn, is quite unhealthy. Not only does it make you fat, it also puts a strain on the liver and promotes diabetes and cardiovascular disease.

And: “A high fructose consumption changes hundreds of genes in the brain. Among other things, memory suffers as a result, ”Xia Yang from the University of California in Los Angeles told The US researcher and her team found this out in experiments with rats.

For their examination, they gave the animals water containing fructose to drink. For several weeks, the rodents consumed amounts of fructose that correspond to a daily lemonade consumption of one liter in humans.

Lost in the maze

The sugar cure worsened the animals' memory performance considerably: it took them twice as long to find their way out of a familiar labyrinth. "We assume that the fructose has weakened your memory," says Yang. Previous studies have already shown that high fructose consumption is associated with mental decline in the long term. “It is therefore believed that fructose could even be a risk factor for Alzheimer's,” says Yang.

An analysis of more than 20,000 genes in the rat brain showed that more than 900 genes had changed under the high-fructose diet. Some of the sugar had attached certain groups of molecules to the DNA building block cytosine or decoupled them from the cytosine. In this way - one speaks of epigenetic changes - genes can be activated or shut down. In this way, the body essentially controls the function of the cells.

900 incorrectly programmed genes

More than 200 genes in the hippocampus, which are crucial for memory performance, were changed. Far more, namely around 700 genes, were affected in the hypothalamus, which plays a central role in regulating metabolic processes. "Our study shows that fructose interacts in a special way with the biochemical machinery of the body and brain," explains Yeng.

Protective fatty acid

And the researchers found something else: Protection against the fructose-related changes in the brain apparently offers a special fatty acid: Docosahexaenoic acid (DHA), which is one of the omega-3 fatty acids. Rats that ate a diet particularly high in DHA in addition to the fructose water were not impaired in their memory performance. They could remember the path that led out of the labyrinth as well as animals that had only received water. "DHA restores the changed genes to their original state," explains Yang, "and not just one or two, but all of them."

Lubricant for the brain

DHA is an important part of cell membranes, especially those of brain cells. It helps to link the synapses of nerve cells together and is therefore important for learning and memory. The body can produce the substance itself, but not in sufficient quantities. Therefore, DHA must be ingested with food. "The best source of this is wild salmon, but walnuts also contain a lot of DHA," says Yeng.

The scientists are currently analyzing the influence of fructose on other organs such as the liver, but also on adipose tissue, which play a decisive role in the development of cardiovascular diseases and diabetes. “We want to understand what role fructose plays there,” says Yang. The researchers have already observed some physiological changes - for example, the blood lipid levels and the insulin secretion change. "We expect to find seriously altered genes in other tissues as well," says Yang.

Despite the numerous negative effects of fructose - the researchers still recommend consuming whole fruits. Yeng emphasizes: “Fruits contain many healthy components such as antioxidants, vitamins and fiber. And the latter in particular are not only good for the intestines, they also prevent the fructose from entering the body too quickly. "

Source: Qingying Meng et al .: Systems Nutrigenomics Reveals Brain Gene Networks Linking Metabolic and Brain Disorders, http://dx.doi.org/10.1016/j.ebiom.2016.04.008

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