They will help your body break down meals better thus increasing utilization.

I would take digestive enzymes if your having a hard time digesting big doses of protein, your feeling bloated after meals, or your food is not coming out fully digested. Some people take them when their caloric intake gets pretty high to help aid in digesting the large amounts of food they are taking in.

They aren't 100% necessary, but they won't hurt you unless you over do it. Just make sure if your taking a vitamin multipack that your not doubling up because a lot of the packs already digestive enzyme tablets.