A patient that you have not previously seen comes to the window and asks to speak to the pharmacists. He's a young, athletic man holding several types of probiotics. He says in the last 6 months he's gotten food poisoning 3 times. His doctor says it's from E. Coli and he's wondering if you could recommend something to help him.
 
You inquire more about his eating habits and health status. He says he's on a high protein diet and also takes creatine powder, BCAA (branch chain amino acid) supplements and iron sulfate 325 mg for increased endurance. He's training for a triathlon. 
 
He asks you if his supplements are contaminated. He said his food poisoning symptoms included bloody diarrhea, nausea, vomiting, generalized fatigue, all over body myalgias, chills, sweats and a temperature of 103 degrees. He went to his doctor who did a stool sample and found Shiga toxins. The symptoms resolved after 3 weeks without antibiotics, but then returned 2 more times.
 

Mystery: Why is this young, healthy athlete having repeated infections of food poisoning?

 
Solution: The patient is experiencing iron overload which is associated with increased bacterial infections. All vitamins and minerals should be in the natural zone. Levels should not be too high or too low. Both extremes can lead to adverse effects. Iron is no exception to this pattern.
 

Reference
 
Khan FA1, Fisher MA, Khakoo RA. Association of hemochromatosis with infectious diseases: expanding spectrum. Int J Infect Dis. 2007 Nov;11(6):482-7. Epub 2007 Jun 27.