People are so nutrition obsessed that they dose themselves constantly with various vitamin, mineral and herb supplements. Many pet owners impose this obsession onto their animal companions, assuming the pet just can’t get by without some sort of pill or liquid supplement.
While the intention is good, most commercial foods are already well supplied with vitamins and minerals. In the case of some vitamins, such as A and D, there is even a danger of overdosing to the point of toxicity. In a word, be conscious of nutrition (your own, and your pet’s) but don’t go overboard.