There is an old saying that 'if the fire is hot enough, anything will burn'. The idea is that if you are doing enough exercise, you can eat whatever you like. It is true that if you are burning enough calories you can eat high calorie food without weight gain (if calories in = calories out). However, the body is a complex system, and there are countless studies that show the impact of nutrition on health. For instance, there is evidence that moving from Omega-6 to Omega-3 oils and boosting protein, Vitamin-C and Zinc intake can aid in recovery .
Running keeps you fitter and helps prevent illness, but it does not grant invulnerability. Eating wisely can make a difference to long term health and short term performance. This blog will have entries that will look at general nutrition as well running/exercise specific nutrition. You could divide nutrition into four types of nutrient; carbohydrates, fats, proteins and micronutrients. I will blog on these general areas, as well as specific foods and supplements.
Some useful sites for further reading - http://www.pponline.co.uk/encyc/nutrition.htm
 Sports injury: can you eat your way to recovery?