...as are many other foods.
Everyone is different, and it all depends on the amount of exercise you are doing, your normal intake, and the individuals body. You need to do what works for you.
If you can get the nutrients & vitamins through natural means (fruit, veg.), by all means, do it.
I suggested the vitamin supplements as they worked well for me. I had a healthy diet while losing weight, plenty of fruit & vegies, but it wasn't enough intake of the vitamins. As soon as I started taking Vit C & D, I stopped getting sick.