I think moderation is always the key, in anything. From vitamins to chocolate.
My husband just quit drinking. He read a book about enzyme therapy and that alcohol damages the liver, and it all has to do with the body's ability to eliminate toxins, the function of the liver, and if the liver is damaged, or not working as good as it should, at a lesser percent of toxin removal than a fully-functioning liver, the toxins build up in the body, and cause health problems, premature aging, ....
I think a danger can lie when the liver is not completely damaged, therefore you aren't aware that it perhaps is not working at it's fullest capacity, and so it's not doing a full job of eliminating all toxins from your body, therefore some toxins remain in the body without you being aware cause it's not causing damage, but at a certain point the toxins buildup and cause a health problem which you might not link to toxins because it's been such a slow process.
Which is why when your body is not functioning as it should, you should start with a body cleansing, getting rid of toxins, changing your diet so the body will begin to work at it's strongest capacity, and aim to heal the underlying problem, not just the sympton.
I have a lot of respect for doctors, and they definitely know way more than I do, but I also think my health and healing lies in my court, and that oftentimes doctors deal with symptons rather than root causes of illness. I would go to the doctor to find out what my illness is, but I don't know if I'd follow their prescribed path of medication, rather I would take a more total approach that would deal with the entire body, not just the sickness itself.