You should def eat when you take them and it can help to take them before bed. People who feel sick from taking them are usually taking a vitamin that their body doesn't need. There is actually a blood test where you can see exactly what vitamins your body is lacking. GNC has the option of hand picking your vitamin packs. I cant take anything with iron, makes me sick. My iron is really high...even when I was prego my iron was perfect and I could not take prenatal vitamins. Hugs