I have been using energy gels for cycling even before my running days. I never truly understood the purpose of taking them other then it would provide me with energy during my exercise. I ran across a great article from Competitor.com, "What Is the Purpose of Race Nutrition." that talks about the purpose of race nutrition that really puts things in perspective.
Let’s first look what is in the energy gels that many runners use. Most energy gels are made up of simple sugars like sucrose and glucose. I use Gu Rocutane which uses maltodextrin. These are basically just sugars and are some of the worst things you could put in your body. The thing to keep in mind is that you are trying to use these energy sources to complete races or workouts, not use as a dietary supplement.
This is my take on nutrition. I try to non-processed foods as much as possible. When it comes to training though, I need to provide my body with what it needs to make it through the grueling last few miles of my races. Everyone has their own opinion and there are many runners who would rather eat healthy snacks during races, but what the article from competitor.com said was that you are trying to supply your body with energy, not eating healthy. Eating Brussels sprouts and apples won’t provide you with the energy you need even though they are a great, healthy source of carbs. Your body needs the simple sugars.
You should look for an energy gel that will provide you with about 60 grams of carbs per hour according to the article. I tend to take one gel (21 grams of carbs each) every 3.5 miles, or about every 30 minutes. Test out several different types and see what works best. I find the consistency and the ingredients in the Gu Rocutane work great for me. It is a little more pricy than some of the other brands though. You can also find gels with or without caffeine. I find the caffeine can give you an added boost later in a race.
One major point I want to make is that you should be practicing your gel consumption during your long runs so your body will be used to digesting while running. It will make your race more pleasant and could help minimize trips to the dreaded port-o-potty, or behind a bush. Let me know what your favorite energy gel or supplement is and why.