Improve your health, fitness, and fight seasonal depression all in one. 

Daylight savings time is here, whether you like it or not. That means more cold weather, less warm sun, and for some people, vitamin D deficiencies, which, like any vitamin deficiency, can cause a host of health problems. This week, though, researchers completed a preliminary study on vitamin D and found that if you do happen to get enough this essential vitamin, it not only reduces the risk of heart disease, but also helps you exercise more strenuously, while simultaneously exhibiting lower signs of exertion. In layman's terms, vitamin D helps you exercise harder without becoming more tired, or even more simply, vitamin D turns you into Superman.

Vitamin D, which is also a hormone, is used in such critical bodily functions as the formation of bones and teeth, as well as in the absorption of other nutrients, but a lot of people don't get enough through diet alone. Luckily, most everyone enjoys some fun in the sun, which exposes skin to ultraviolet B rays and generates substantial amounts of vitamin D in the body. But, once winter hits and sunlight dissipates, even more people fail to get the necessary amount of this critical vitamin. Understanding this conundrum, researchers from Queen Margaret University in Edinburgh, U.K., sought to investigate the bodily mechanisms and subsequent health benefits people with vitamin D deficiencies were missing out on.

In the study, participants were matched by age and weight and either given 50 micrograms of vitamin D, or a placebo, each day over a period of two weeks. At the end of the two weeks, participants went through a series of tests, and those who took the supplement not only showed lower blood pressure levels, but also had lower levels of the stress hormone cortisol. The most surprising finding, though, was that in a fitness test, participants who had taken the vitamin D supplement were able to cycle, on average, 6.5km in 20 minutes, compared to just 5km before the two week period had begun. Even with the 30% increase in distance, participants showed lower signs of physical exertion, which may be due to vitamin D's ability to lower cortisol levels, which has been known to restrict and narrow arteries and blood vessels.