According to a new study by UCLA life scientists, published online in EBioMedicine, dietary ‘fructose’ can damage the genes in our brain which in turn leads to the formation of metabolic disorders (MetDs), but the effects may be reversed by eating foods rich in omega-3 fatty acids.

When hundreds of the essential genes present in our brain are disturbed or changed, they can cause a range of diseases such as diabetes, cardiovascular disease, Alzheimer’s disease, attention deficit hyperactivity disorder, Parkinson’s disease, depression, bipolar disorder, and other brain diseases etc. The sugar fructose, which is reaching the status of a staple in the Western diet due to the presence of high fructose corn syrup (HFCS), has been found to cause those damaging changes in the genes. However, even if such damages have occurred, there may be a solution to reversing the detrimental effects in the form of omega 3 fatty acids. The study also found consumption of foods rich in the polyunsaturated fatty acid i.e., PUFA ‘Docosahexaenoic acid’ (DHA) can reverse damages caused by fructose to the genes.

Since its introduction in 1967, HFCS has been added in almost all types of processed foods in the US, either to enhance taste or to increase the shelf life of the edible products. In 2005, it was found an average American consumes about 142 pounds of ‘added sugars’. Likewise, in 2014, the US Department of Agriculture (USDA) reported an individual consumed more than 27 pounds of HFCS sweeteners from their food, and that the rate of consumption is not expected to reduce in the near future. HFCS is an inexpensive ‘fructose-glucose’ liquid sweetener made from corn starch and added heavily in beverages, processed products, syrups, desserts, baby foods and even fruits. In recent years, HFCS has generated a negative image since studies have accused the corn sweetener of being one of the main culprits behind advent of the child obesity epidemic in the US in the last 30 years.

The genomics research being discussed is the first time all of the effects of fructose consumption on genes, pathways and gene networks have been studied in those particular regions of the brain, which control metabolism and brain function.

Xia Yang, a UCLA Assistant Professor of ‘Integrative Biology and Physiology’, was the senior author of the study while Fernando Gomez-Pinilla, a Professor of both ‘Neurosurgery’ and ‘Integrative Biology and Physiology’ at UCLA, was the co-senior author. Qingying Meng, a post-doctoral scholar in Yang’s laboratory, was the lead author of the study.

“DHA changes not just one or two genes; it seems to push the entire gene pattern back to normal, which is remarkable,” said Xia Yang, who also is a member of UCLA’s Institute for Quantitative and Computational Biosciences. “And we can see why it has such a powerful effect.”

DHA is found naturally in human brain cells but cannot be produced by the body. In the brain DHA helps strengthen the synapses which enhance our memory and learning capabilities, but the quantities although sufficient are not high enough to fight MetDs. Foods rich in dietary DHA include fish and fish oil like, salmon, but not the farmed quality, walnuts, flaxseed, and different fruits and vegetables.

“The brain and the body are deficient in the machinery to make DHA; it has to come through our diet,” said Fernando Gomez-Pinilla, who is also a member of UCLA’s Brain Injury Research Center.

In the study the researchers tested the effects of fructose and DHA in rats trained to escape from a maze. The rats were divided into three groups and two of the groups were given water supplemented with fructose. The amount of fructose added to the water was equal to the amount of soda a person roughly consumes in one day. Out of the two test groups one was only given the fructose water, while the other was also given a diet rich in DHA along with the fructose water. Meanwhile, the third rat group was set as the control group and given only simple water.

After a period of six weeks the rats were put back in the maze. It was found the maze crossing ability of the rats given only fructose water became slower than both of the other groups. The results indicate the high fructose diet had impaired the memory of the rats. Meanwhile, the group given both fructose and DHA had a maze crossing speed equal to the control group which had retained its normal speed. It was concluded that DHA may be useful in eliminating the harmful effects of fructose on the brain.

Other tests performed on the rats revealed the group consuming only fructose water had very high levels of blood glucose, triglycerides and insulin, when compared to the other two groups. High levels of glucose, triglycerides and insulin have been implicated as the precursors of obesity, diabetes and other MetDs in humans.

More than 20,000 genes in the rats’ brains were sequenced by the researchers. It was found there were more than 700 genes in the hypothalamus, which is the metabolic control center of the body, and 200 genes in the hippocampus, which regulates learning and memory, are changed or damaged by fructose. All of the genes impaired by fructose consumption are known to work for the regulation of metabolism, cell communication and inflammation. It was suggested fructose adds or removes the biochemical group to the protein ‘cytosine’ is one of the four nucleotides which make up the DNA structure, indicating fructose plays a critical role in turning genes ‘on’ or ‘off’.

Two genes called ‘Bgn’ and ‘Fmod’ were found to be the first genes altered by fructose in the brain and their alteration causes a chain reaction which affects other genes. Studying and targeting these two genes can be the next step in developing drugs to target MetDs.