Purple carrots originated in Persia and have been used for thousands of years.
Why are they good for you?
Carrots are a great source of fibre and vitamins A, K, C and B6. They're low-GI and the red-orange pigment that gives carrots their colour (beta carotene) provides protection against macular degeneration and the development of cataracts for the elderly. Purple carrots contain all the nutrients of orange carrots, but they've also been shown to have greater anti-inflammatory and anti-oxidative effects. A recent Australian study showed that the purple pigment that cases the carrot contained up to 28 times more anthocyanin antioxidants than those in orange carrots. Carrots in general help protect against cardiovascular disease and cancer.
How do you use them?
They may look different, but there's no trick to cooking purple carrots. Just treat them the way you would orange carrots. To store your carrots, place them in a plastic bag in the coldest part of your fridge. If the carrots still have their green tops, remove them as they'll take moisture from the carrots and cause them to wilt.
Source - Notebook: - November 2010 , Page 81