Instead of just pitching expired vitamins you can add them to compost or dissolve them in water and give it to your plants.
Source: Had the idea and verified it at the Mayo Clinic website.
By ann from Saint Peters, MO
Put one vitamin tablet, I use Pre-natal Vitamins sold at Walmart, at the bottom of a dug hole for new transplants. As the tablet dissolves it feeds nourishment to the young plant.