How you behave may increase your need for supplementation. For example, smoking or drinking alcohol to excess dramatically saps your reserves of vital nutrients. In both cases, dietary supplementation is not an option – it’s a requirement.
On the other hand, if you’re an avid mountain climber or high-performance athlete, you use up nutrients faster than the average person. The same is true if you work in a physically demanding occupation. Your performance will be improved with dietary supplementation.