Alcohol does certain universal things to our bodies, so why do we offer a variety of different advice to people, depending on their age and sex. The simple answer is that alcohol affects our bodies differently depending on our age and on our sex.
The recommendation of 18 years being the ‘legal age’ was based on the effect alcohol has on our developing organs, from our brains to our livers and stomachs. So the younger you drink the more adverse the effects on your internal organs. This again come into play when we get older, we should look at our consumption, as this again effects us to a greater degree with age. People who start drinking younger tend to drink more the older they get, thus they have more alcohol problems.
While our age affects us, so does our sex, women for reasons of biology suffer from the effects of alcohol more than males, this is why women are more liable to suffer medical issues around, for example their livers than men. This is why women should consider abstaining from alcohol when they are pregnant, it may not be easy, help is available, so is advice. Alcohol can have a serious adverse and non-reversible effect on the unborn child, this is why the zero alcohol limit is now agreed across the UK.
There is information available on this from Tayside Council on Alcohol and Alcohol Focus Scotland.