I really have not heard this but I still believe - everything in moderation.
For those fighting a disease and will have dye off, the coffee enema is something is important for your health. Not being able to rid yourself of the cells will make your body toxic; use the coffee enemas therapeutically.
If you are worried about malabsorption of fat soluble vitamins you might want to adjust when you take them so as to eliminate that risk. Give your body time to absorb them before doing the coffee enema.