A lotion that stimulates production of the skin pigment melanin induces a deep tan in specially bred laboratory mice. Those mice have skin similar to that of red-headed, fair-skinned people, who are notoriously poor tanners.
The animals developed their tans without being exposed to the sun and its ultraviolet (UV) rays. Further tests showed that the additional melanin protected the mice against UV-induced DNA damage, sunburn, and skin cancer.
The active ingredient in the lotion is forskolin, an Asian plant extract that has been used to treat health problems. But scientific studies of the compound in the past few decades have shown no clear benefit, says study coauthor David E. Fisher, an oncologist at the Dana-Farber Cancer Institute and Children's Hospital in Boston. Nevertheless, past tests had shown that forskolin can rev up production of cyclic AMP, a molecule that's instrumental in producing melanin.