Mohammad Sa'idi, international affairs deputy of the Iranian Atomic Energy Organization, claims heavy water (which Iran is now producing) is medicinal. He states in this Iranian News Channel interview that it's used to treat AIDS and cancer.
Yes, heavy water in high enough concentrations inhibits mitosis, stopping cell division. But if you drink it, it rapidly diffuses throughout your body, as opposed to concentrating at a tumor or infected T-cells; since your body is about 70% water, you'd need to drink only heavy water for a week or so to make any difference — and it would be a bad difference for you, similar to the effects of radiation poisoning.
As a general principle, nobody this nutty should be involved with nuclear anything.