People injure themselves in these races because they push too hard generally because they don't listen to their body. It's easy to ignore heat stroke and pass it off as just being tired and can certainly lead to organ failure.
Micronutrients are vastly unimportant if you eat a balanced diet. If your dieting consists of only eating chicken and rice, then yes you probably need to supplement. If you regularly have vegetables, a variety of meats, sparing amounts of fruit, there is no need to supplement micronutrients for weight loss.
And yes
@VirtualLarry there is nothing special about losing weight and thousands if not millions of people have done the exact same thing Al Roker has done, all it takes is the correct mindset and some actual commitment. If you constantly have excuses, you'll never progress.
For most people they need a real health scare in order to change their life. It may be a heart attack, it may be something else, but at that point much of the damage is done, however any changes they make will hopefully prolong their life. For others it may be seeing things happen around them that they can't participate in, eg the birth of a child, watching families do things together, etc.
You have to first decide to do something on your own, and then execute on it. Plenty of people can help you, but only you can make it stick.