Evidence suggests that the average person needs 5,000 IU of vitamin D3 per day to achieve a target serum level of 50 ng/mL. Problem? Food sources high in vitamin D don’t offer enough to help you reach this goal (that is, unless you drink 50 glasses of milk a day).

And although it’s called the “sunshine vitamin,” most people don’t get enough safe exposure to the sun to achieve optimal levels of vitamin D. Age, latitude, skin tone, season, climate, skin tone, and biological sex all affect a person’s ability to produce vitamin D. while in the sun, so it’s not a reliable source for most.

The most effective way to achieve and maintain optimal serum vitamin D levels is to take a high-quality supplement that provides 5,000 IU of vitamin D3 (bonus points if it has built-in healthy fats for improved bioavailability). Tip: You can find mindbodygreen’s favorite vitamin D supplements here.