Little packets of silica gel are found in all sorts of products because silica gel is a desiccant -- it adsorbs and holds water vapor. In leather products and foods like pepperoni, the lack of moisture can limit the growth of mold and reduce spoilage. In electronics it prevents condensation, which might damage the electronics. If a bottle of vitamins contained any moisture vapor and were cooled rapidly, the condensing moisture would ruin the pills. You will find little silica gel packets in anything that would be affected by excess moisture or condensation.