Final answer:
The 'old man smell' is primarily caused by the production of 2-nonenal, a chemical that results from the breakdown of omega-7 unsaturated fatty acids on the skin through oxidation. Factors like hygiene practices, diet, and overall health can also influence the strength and presence of this scent.
Step-by-step explanation:
The 'old man smell' commonly referred to is actually a result of a natural process involving the breakdown of certain skin glands that produce sweat and oils. As people age, their body chemistry changes, and one of the changes is that the skin produces more of a chemical called 2-nonenal. 2-nonenal is created when omega-7 unsaturated fatty acids on the skin degrade through oxidation. The process is a normal part of aging and may be more pronounced in men due to higher concentrations of these fatty acids.
Further contributing factors include personal hygiene, diet, and the overall health of the individual. For example, a lack of proper hygiene practices can lead to the accumulation of bacteria on the skin, which then break down the sweat and oils, potentially exacerbating the odor. Additionally, certain foods can alter the body's scent. Finally, as we age, our body becomes less efficient at repairing and regenerating cells, which can also contribute to different body odors.