Does your body odour change as you get older?

From your forties onwards, your body odour contains a compound that is completely absent in younger people: 2-nonenal. This is a waste product formed when certain fatty acids in the outermost layer of your skin slowly oxidise. It has a greasy, grassy smell that is perceived as unpleasant. In test subjects between the ages of 26 and 39, 2-nonenal was not detected at all; from age 40 onwards it was, and the amount continues to rise with age.

The mechanism is reasonably well understood. As we age, the quantity of certain unsaturated fatty acids on the skin surface increases, as do the oxidation products released in the process. That combination leads to the formation of 2-nonenal. This has not only been demonstrated in laboratory research, but positive associations have also been found between the concentrations of those fatty acids, the oxidation products, and 2-nonenal in people themselves.

A study focused on developing new measurement techniques names four other volatile compounds as potential age indicators in body odour. However, that finding is still in its early stages: it was not the primary aim of that research, and for now you cannot draw many firm conclusions from it.

There is another factor to consider: as you age, you also perceive smells less well yourself. Both sensitivity to odours and the ability to identify them decline, even when measured over a period of five years. Older people also notice this themselves. This means that a change in odour that others can detect may be less readily noticed by yourself.