At UTHSC, my postdoctoral fellows and I found that melatonin may help prevent cancer by serving as DNA’s personal bodyguard. We made this discovery by injecting rats with safrole, a toxic substance known to cause cancer by unleashing large amounts of free radicals. We injected half of these rats with melatonin as well. Twenty-four hours later, we examined their liver cells for DNA damage. The animals that had been given safrole alone had sustained significant damage to their DNA; if the experiment had continued, many of them would have developed liver cancer. Careful measurements revealed that the DNA of the melatonin-treated rats had sustained only 1 percent as much damage.

I was astounded by these results. Most scientific studies produce barely significant results. Scientists long for those rare studies that provide dramatic evidence–what we call a robust effect. Well, this was a robust effect if we had ever seen one. In fact, my initial thought was that something must have gone wrong in the experiment, and I suggested that we do it again. We got the same results the next time, and the next. As the significance of the study began to sink in, I was awestruck by the apparent potency of melatonin. We had given the animals 750 times more of the toxin than melatonin, yet the hormone had offered near total protection.

Free radicals damage surrounding molecules in a nanosecond. Unless an antioxidant is in the immediate vicinity, they cannot be prevented from doing so. Thus an antioxidant must offer “on-site” protection. But most antioxidants cannot do this. For example, vitamin C is water soluble, which limits it to fluid environments su9ch as the cytosol, the watery interior of the cell. Cell membranes are fatty molecules; taking vitamin C to protect them would be like trying to put out a fire in the attic when the fire extinguisher is locked in the garage. Melatonin is both fat and water soluble–a rare occurence in nature–making it the only known antioxidant that can protect all parts of the cell. Furthermore, because melatonin can navigate all the barriers in the body with ease, including the blood-brain barrier and the placental barrier (which protects the unborn child), the antioxidant-hormone can protect every cell in the body.

Excerpted from Melatonin: Your Body’s Natural Wonder Drug, Chapter 3, pages 24-34.