A study showed that if anyone eats only one type of food to survive, usually that person will start to get sick after about a month. This is totally understandable. It reminds me that even if we are deserted on an island, we have to find ways to get a balanced diet. Just like the way in the movie "Cast Away", if Tom Hank's character only ate fish or seafood, he would likely have gotten thyroid disease. However, under that circumstance, survival is the most important matter. Anything else is actually insignificant.