People who eat more dairy while dieting end up with higher levels of vitamin D in their blood than those who eat less dairy—even if they both started out low on vitamin D.

Even though people ate more dairy, their body didn’t make more of the active form of vitamin D—so the hormone that might affect fat cells stayed the same.

Eating more dairy didn’t change the hormone that regulates calcium in the blood—so the body’s calcium system didn’t respond the way some theories predicted.

In men taking 2000 IU of vitamin D daily for 12 weeks, blood levels of vitamin D rise more when their diet is high in fat than when it is high in carbohydrates.

Taking a daily vitamin D pill of 8000 IU for 3 months can boost vitamin D levels in young men from dangerously low to healthy levels, while those who take a fake pill (placebo) stay low.

Men who had excess belly fat saw their vitamin D levels go up by 27% after a year of eating better and moving more—even though they didn’t take any vitamin D pills or supplements.