Sorry to double-post, but two further things occurred to me:
1) A very recently-qualified doctor once told me to avoid caffeine. She said that, 'Earl Grey tea is fine, though - it's decaffeinated'. (It's not: doctors do make mistakes and sometimes, they're very simple ones. Doctors are human too.)
2) In the UK, increasingly, doctors are recommended to tell all pregnant women to avoid alcohol entirely, throughout their pregnancies. Many doctors have acknowledged that a small glass of wine every now and then is not harmful, and that - especially later in pregnancy - it may be quite good for the mother if she feels she is able to drink a little red wine on rare occasions.
Despite this, many of the same doctors nevertheless agree that they would recommend pregnant women to avoid alcohol, despite the above. Firstly, they do so because, sadly, some people will think that if a small amount of wine infrequently is ok, then so is a large amount regularly. Secondly, they do so because there is so much scaremongering in the press about the dangers of alcohol that it is much better for women's peace of mind if they have a single, simple piece of advice to follow.
It seems to me that there could be something similar going with Aspartame, Quinault?