VFOOD1940 - Items benefiting from the relief: what is food?: food supplements (dietary supplements): enriched foodstuffs
The addition of a supplement to an otherwise normal food product (such as vitamin-enriched bread, fruit juice with added fibre) does not change the usual liability of the product; this is judged according to the nature of the product as a whole.
In the case of Smith Kline Beecham (LON/95/1704A) the tribunal ruled that the inclusion of added fibre in Ribena blackcurrant drink did not change its essential nature as a beverage, and it was therefore still standard-rated under excepted item 4.