It is a rabbinic prohibition to eat something non-kosher, even if not eaten in the normal way of eating. However, swallowing pills which may be non-kosher is permissible for a person who is unwell, for a combination of two reasons: 1) because the pills are swallowed whole, and 2) because they are tasteless. Regarding this halachah, illness is defined as a general feeling of malaise, or what is termed miktzas choli, a minor sickness or pain. (The halachah is different for a child; anything a child needs is considered an illness.) However, if an alternative kosher medication is available, the heter does not apply. If a pill has a taste, a solution would be to enclose it in a kosher capsule or wrap tissue paper around it before swallowing it. Healthy people may not take non-kosher vitamins or supplements to strengthen their bodies in any way, as the heter only applies in a case of illness.