Nutritional boffins are singing the praises of a green veg that's packed with more vitamin C than your average orange, and Harvard hotshots are flagging up spinach as a top-notch immune system booster. Vitamin C, also dubbed ascorbic acid, is a bit of a wonder nutrient, famed for its cell-protecting prowess, skin and blood vessel maintenance, bone and cartilage support, and even its role in healing our scrapes and bruises. The history books first mention spinach cropping up in 7th-century China