A: There is a highly specialized and lengthy process used to manufacture Ig. It begins in blood centers across the country where tens of thousands of healthy individuals donate their plasma (the portion of the blood where the immune globulins and other blood proteins are contained).
Runners, especially those training for long distances such as marathons, should consume .5 to .75 grams of protein per pound of body weight. Good sources of protein are fish, lean meat, poultry, beans, nuts, whole grains, egg whites, low-fat milk, low-fat cheese and some vegetables.
There is no reason to change that for a race. The only thing you really need for your half marathon nutrition is breakfast two hours before you run and enough fluid to ensure you are hydrated before the start of the race. You might find you need water or a sports drink during the half marathon.