One of these DNA segments are located close to the CYP1A2 gene, encoding a cytochrome protein 450, which is responsible for the caffeine is metabolized in the body. The second fragment is in close proximity to the AHR gene, which controls the activity of CYP1A2. The identified DNA fragments may regulate the activity of these two genes.
As stress researchers, caffeine consumption associated with various physiological health effects (both harmful and beneficial). Knowledge of genetic conditions that consumption may thus help to study its effects on human health.
Caffeine is the most popular psychoactive substance in the world, for example, about 90% of US adults admit they regularly drink coffee and other drinks containing this substance.
However, people are very different with respect to the consumption of foods with caffeine. Some can not imagine life without coffee, while others do not understand, how can you be dependent on him.
As the co-author Dr. Marilyn Cornelis, at Harvard University in Boston, the study of twins showed that differences in the consumption of caffeine depends to a large extent - from 43% to 58% - of the genes.
To find out which genetic factors may play a role here, Doctor Cornelius, and his colleagues analyzed data collected from five large studies involving more than 47 million Americans of European descent.
Each intake of caffeinated beverages was assessed using questionnaires. The analysis includes, among others, age, gender, smoking history, which often goes hand in hand with coffee.
It turned out that people who have two copies of a particular variant of a DNA fragment, which lies close to the AHR, daily consumed about 44 mg of caffeine, and more than the persons deprived of this option at all. As explained by one of the co-authors of the study, this corresponds to the amount of caffeine contained in a cup of tea or cola, or about one-third of a cup of coffee. In the case of the second DNA fragment, the holders of two copies of a particular embodiment of consumed daily for more than 38 mg of caffeine.
Smoking had no effect on noticed by communication.
As suggested by the researchers, the genetic variations that have been found in fans of caffeine is likely impair the metabolism of this compound in the body and means to maintain that level, which produces the same effect - they must consume it in large quantities.
But to understand these differences at the level of physiology experiments are needed, not just a statistical analysis - the authors say.
According to studies, two genetic variants identified are responsible for less than 1% difference in the consumption of caffeine. This indicates that there should still other embodiments, which to this effect.
The latest work is seen as an expressive link between variants of CYP2C9 gene and ADORA2A and caffeine consumption.
Scientists emphasize that the search for the genes that determine susceptibility to addiction is difficult. Sometimes because it is unknown whether it is necessary to search among the genes that are responsible for the metabolism of the substance, or among the genes that regulate the process. As commented Dr. Kaporaso, in the case of caffeine was able to find the answer at the liver, but not brain.