Technically speaking, water is not a nutrient. But don't tell that to a runner. Without proper hydration during a long run, the blood becomes thicker, the heart beats faster and you'll become tired faster. Staying hydrated is the ultimate offense. Before a run, make sure your urine is nearly clear. Carry a water bottle with you or stash several along your running route. Better yet, take sports drinks that will hydrate while also providing you with carbohydrates and electrolytes. There is a danger of drinking too much, however. You can gauge when you've had enough by the feel in your stomach. If you can feel or hear the liquids moving about, then it's time to back off [source: Bryant].
A small infusion of carbohydrates about every 45 minutes will help you avoid what is regularly referred to as bonking -- an absolute, lethargic tiredness. Energy gels, protein bars or even a peanut-butter-and-jelly sandwich stuffed into a bag and placed in a running belt are good choices for long runs.
Good long-run nutrition doesn't end when your workout does. In fact, eating after a run is vital to rebuilding your muscles and preventing an unnecessary breakdown in your immune system defenses. There are many options. Think primarily about eating a 4-to-1 ration of protein to carbohydrates and consuming that food within 30 to 45 minutes after your workout. It's during this period of time that your body's cells are sponge-like in their receptivity to fuel [sources: English; Shea].
Yes, running is an individual sport, but your nutritional knowledge can power the internal defense and offense that'll make you strong for today's run and tomorrow's.