Eat food like a sane person. If you don't have any underlying problem that prevents you from absorbing a specific nutrient you most likely don't need any supplementation. If you do think that you might have such a problem speak to a doctor.

Absolutely wrong. This mistaken belief comes from a boolean model for health - that is, that you are sick or healthy, rather than one of a million levels and variations of slightly-more or slightly-less healthy. It also fails to acknowledge all the widespread deficiencies, and the safe compounds we've discovered that provide health benefits but aren't found in food.

There's also the fact that taking supplements lets you optimize micronutrients and macronutrients separately. For example, if you want more vitamin C which is mostly in fruit, but don't want sugar which is also found in fruit, then it's easy. The same applies to things you want to avoid. Using supplements prevents there from being a tradeoff between micronutrient intake and other things you might care about.