Is Westerners' love of junk food and booze genetic?

Scottish scientists have identified a genetic region that may have a role to play in why humans crave 'fatty foods'. The researchers, from Aberdeen University, identified a DNA region close to the galanin (GAL) gene that helps to regulate the production of this protein.

Galanin is a neuropeptide — a protein-like molecule found in the brain — that has an important regulatory role in the hypothalamous and amygdala regions. The former region has many functions, including a role in controlling appetite and thirst, while the latter is believed to be involved in emotion. The study itself looked at GAL gene function and regulation in both animals and humans.

The scientists discovered that different genetic variants close to the GAL gene affected how much protein was produced. The researchers found that two specific bases — the letters that make up DNA, being G, A, C or T — in this region were different in certain populations. For example, CA variants were more common in Asians than Europeans. They also found that CA variants were less active than GG variants, reducing the amount of protein produced. 

Earlier studies in animals showed that increased levels of GAL protein meant that they were more likely to seek out calorific foods. The scientists involved in the latest study speculated that evolutionary pressures might have caused the CA variant to be less common in Europeans, because of the colder climate and the need for people to eat more calorie rich foods in order to survive.

This is only a theory and the researchers are careful to note that their data does not necessarily support these wider conclusions. However, the leader of the study, Dr Alasdair Mackenzie, told the Daily Mirror: 'If it [the GAL gene] is turned on too strongly, we are more likely to crave fatty foods and alcohol'.

Other groups claim to have found genetic variants in the same region that they believe are linked to major depressive disorder (MDD). Scientists have long suggested that mood, appetite and eating behaviour are closely linked.

This research was funded by a number of organisations, including the Wellcome Trust and UK Medical Research Council; and the findings were published in Neuropsychopharmacology Journal.