Tomatoes can cause yellowing of the palms of the hands when eaten in excess. Tomatoes are rich in carotenoids and eating too many of them can increase the concentration of carotenoids in the blood and tissues thereby causing yellowing of the skin on the palms of the hands; the yellowing of the palms may be more pronounced if you have hyperlipidaemia and diabetes, so such patients have a reduced ability to convert beta-carotene to vitamin A. As a result, the concentration of carotenoids in the body will be higher and the skin will be more yellow and harder to fade.