EPISODE 90 - ADRB2 GENE

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This week we turn our attention to a gene called ADRB2, which plays a role in response to exercise, VO2max trainability, and sensitivity to both fats and carbohydrates. When talking about ADRB2, we are actually interested in two single nucleotide polymorphisms (SNPs) found in the gene, given the imaginative and catchy names of Arg16Gly and Gln27Glu. This gene codes for something called the beta-2 adrenergic receptor, whose job it is to bind to adrenaline.

The small changes in this gene that we are interested in are therefore related to how sensitive our body can be to the effects of adrenaline. As such, changes in this gene can affect the heart, increasing heart rate, allowing more blood to be pumped around the body, transporting nutrients and oxygen to muscle; increasing the size of our bronchus and bronchioles (commonly known as the windpipe), allowing more oxygen to be taken in to the body; and increasing the breakdown for fat as use for a fuel during exercise. Due to these effects, different versions of ADRB2 have been associated with better response to endurance exercise, and also better improvements in VO2max.

One study that looked at this, for example, was published in 2007. The researchers compared a group of elite endurance athletes with a group of sedentary people. The elite athletes all had a VO2max of over 75ml/kg/min, whilst the sedentary people all had a VO2max of under 50ml/kg/min. After analysing the groups, it was found that those with the G allele of the Arg16Gly SNP were more likely to be in the sedentary group, whilst the A allele was over-represented in the elite athletes. Similar results have been found for the Gln27Glu SNP, with the G allele again associated with a lower VO2max.

So that’s the response to exercise, but this gene also plays a role in carbohydrate sensitivity. A paper published in 2003 in The Journal of Nutrition found that G allele carriers of the Gln27Glu polymorphism were more sensitive to carbohydrates, such that with a high carbohydrate intake, those people had a much higher obesity risk. Other research suggests that this gene can affect how much weight people lose when on an energy-restricted diet.

Overall, then, the two SNPs within ADRB2 can have an impact on how well you respond to both training and carbohydrates and fats.