American scientists have bred a new strangely - colored variety of tomatoes called Indigo Rose, which is being heralded as a new superfood with even greater health benefits than normal red varieties.The new type of tomatoes was bred by Professor Jim Myers at the University of Oregon in the United States. The idea came about when a graduate student was pursuing interests in looking at the health benefits of tomatoes. The scientists found some tomatoes with purple pigmentation and tests revealed that an antioxidant called anthocyanin was providing the color, the same as that of blueberries. They crossed the purple tomatoes with some wild tomatoes and eventually came up with a black strain. During the growth process, Indigo Rose starts out green like all tomatoes; but, when the sun hits the fruit, it turns black rather than red. Dark tomatoes are not as sweet as normal red tomatoes and have a more savory flavor. American nutritionists advise people to eat more of the jet-black variety and less of the sweet version. Black tomatoes are said to be healthier than their red cousins as they have more anti-oxidants to help fight diabetes and obesity. Black tomatoes are just the latest in a long line of oddly-colored vegetables hitting supermarket shelves. This time last year, white asparagus went on sale for the first time, joining the ranks of yellow zucchinis and purple-sprouting broccoli.