There are many PO Skin Whitening Supplements in the market. Many contain glutathione which is a strong antioxidant that helps defend the skin from oxidative stress damage and can have skin whitening effect. But sadly, glutathione is poorly absorbed when taken orally, so the effectiveness of oral glutathione supplement is questionable. On the other hand, the precursor of glutathione, L-Cysteine, is readily absorbed by our body when taken orally and it boosts our liver to produce glutathione. Carotenoids is another group of natural chemicals which can act against UV damage and melanin (dark pigments) synthesis. Tomatoes are rich in carotenoids but consuming high number of normal tomatoes will cause tan-orangy staining on the skin. To combat this, scientists have come out with a new form of carotenoids from a breed of non-GMO tomatoes which contain CLC, colourless carotenoids. Therefore, an oral supplement which contains both L-Cysteine and Colourless Carotenoids (eg. Crystal Tomato Plus) is proven to be very effective in skin whitening.