Instead of worrying about which nutrients compete for absorption, a smarter long-term approach is to focus on nutrients that enhance each other’s absorption.

Some people say they have trouble sleeping when they take vitamin D at night. The theory? Vitamin D is known as the "sunshine vitamin", tied to our circadian rhythm.

Let’s be real—most of us aren't going to take every vitamin under the sun. And while multivitamins give you a little bit of everything, that...