Genes and love for coffee 19.10.2014

There are people who cannot live without coffee for a day, and there are those who are completely indifferent to it or cannot stand it at all. Of course, the reason for such a difference in tastes may lie in different upbringing, different cultural environments, etc. - it can be assumed that if the adults in the family all drink coffee, then the children will get used to it, and there, you see, they will fall in love. But is there also a genetic background here?

An article appeared in the journal Molecular Psychiatry, the authors of which - several dozen researchers from different scientific centers - talk about the genes on which the love of coffee depends. Such interest in coffee on the part of scientists is quite understandable: on the one hand, it is one of the most popular products, on the other hand, coffee and caffeine have many interesting physiological properties. For example, coffee consumption is known to reduce the risk of type XNUMX diabetes, liver disease, and Parkinson's syndrome; there are suspicions that coffee also affects the likelihood of cancer and cardiovascular diseases, but how and in what way this effect manifests itself is not yet completely clear. The intrigue in coffee affairs is also added by the fact that it is not always clear to whom to attribute this or that effect: whether the reason is in caffeine, or in some other substances, since, as it turned out, decaffeinated coffee can also have a beneficial effect. to physiology.

To find out why some love coffee and some don't, Marilyn Cornelis of the Harvard University Health Department (USA) and her colleagues analyzed the genes of more than 120 people, Europeans and African Americans. They found eight loci in the genome, which depended on the love of coffee; single nucleotide substitutions in them led to the fact that coffee consumption increased or decreased.

What genes correspond to the discovered zones of "coffee love"? Firstly, the authors of the work thus managed to find two new genes involved in caffeine metabolism - POR and ABCG2. Modifications in them greatly influenced the amount of coffee consumed. The other two genes that it depends on, BDNF and SLC6A4, are associated with the work of the brain, or rather, with the work of the pleasure center and the reward system. Some genetic modifications reduce the synthesis of the BDNF protein (or brain-derived neurotrophic factor), and then a person becomes indifferent to coffee - apparently due to the fact that he does not enjoy it. On the other hand, changes in the SLC6A4 gene, which determines the transport of the neurotransmitter serotonin, increase coffee cravings.

Another pair of "love or dislike coffee" genes are GCKR and MLXIPL. They are not related to caffeine metabolism or neurotransmitters, but are involved in the metabolism of fats and carbohydrates. Modifications in the GCKR gene increase the brain's sensitivity to glucose, and thus likely affect a person's craving for the popular drink. (Here, perhaps, we should collect more information about the difference between lovers of coffee with sugar and those who love coffee in any form, even with sugar or without.) As for the MLXIPL gene, in its case one simply has to state the connection between him and the love of coffee - so far there is not even any guesswork about the mechanism of this connection.

Of course, taste buds (and their genes) should also influence our attitude to coffee, but, as we see, it is not only and, perhaps, not so much about them: love for coffee depends not only on the actual taste sensations. Here we can recall a similar work that was recently published in the journal Alcoholism: Clinical and Experimental Research - in which researchers from the University of Pennsylvania (USA) report that love for alcohol depends on sensitivity to bitter. Addiction to drinking comes from many reasons, including the effect of alcohol on pleasure centers, but the role of purely taste sensations here has long been underestimated. Meanwhile, it is precisely the taste impressions from alcohol that different people can differ dramatically: for some, vodka is delicious, for others it is unbearable bitterness. And it's understandable why John E. Hayes and his colleagues focused primarily on bitter taste receptors.

Humans have 25 genes for these receptors, and it turns out that some of them affect how alcohol tastes. For example, if a person had two copies of the TAS2R38 gene, he became more sensitive to bitterness, while the presence of the TAS2R13 gene, on the contrary, decreased the sensitivity to bitterness. And, most importantly, such genetic variations did affect taste sensations and alcohol consumption, which was confirmed both in statistics and in experimental data. Now it remains only to understand how taste sensations contribute to the emergence of alcohol dependence - that is, whether a person with a weakened sense of bitterness is really more likely to "drink bitter" than someone who is especially sensitive to such taste.