Have you been suffering from low energy levels, muscular weakness, or just an all-around poor mood? If any of these apply to you, it might be time you up your intake of Vitamin D, writes Matt Lupo.

The number of adults that can be categorized as deficient in the Sunshine Vitamin is fairly contested within the medical community. Some nutrition experts like Dr. Rhonda Patrick, a repeat guest of star podcasters Joe Rogan and Tim Ferriss, have explained that an unfathomable 70% of American adults can be considered Vitamin D deficient. On the other hand, a group of medical doctors in a 2016 edition of the New England Journal of Medicine stated that such high estimates are caused by a misunderstanding of “deficiency.”

In any case, we can put the semantics aside and focus on one fundamental truth: Vitamin D is of vital importance to your overall health, particularly  if you’re following any type of fitness program.

If you’ve been feeling off lately, you might consider adding a new supplement to the stack. Here’s why:

Athletic Performance

While Vitamin D has long since been known for its importance in bone health due to its ability to regulate calcium, new research suggests Vitamin D is critical for other body processes such as protein and hormone synthesis, immune response, and cell regeneration. Upon discovering the Vitamin D receptor within the muscle, experts now have reason to believe Vitamin D is paramount to muscle tissue function. While the direct relationship between Vitamin D and athletic performance is still being examined, the evidence seems to very strongly suggest that low Vitamin D levels will hinder your athletic performance.

Mood

During a recent sit-down with Tim Ferriss, Dr. Rhonda Patrick explained how her research identified Vitamin D’s effect on serotonin production in the brain. A neurotransmitter, serotonin is thought to regulate anxiety, happiness, and overall mood. Although low serotonin levels are associated with depression, the fix is not quite as simple as popping a pill as increasing serotonin levels through medication has been associated with decreased arousal and libido. So, the optimal choice is to keep Vitamin D levels right where they ought to be so serotonin levels can follow suit.

Cognition

The benefits of getting your Vitamin D back up to par don’t end with a better gym session. According to Robert J. Przybelski, a doctor and research scientist at the University of Wisconsin School of Medicine and Public Health, Vitamin D “activates and deactivates enzymes in the brain and the cerebrospinal fluid that are involved in neurotransmitter synthesis and nerve growth.” Furthermore, according to two recent European studies at the Universities of Cambridge and Manchester, there is a noteworthy relationship between Vitamin D levels and cognitive impairment. In short, low levels of the vitamin were strongly correlated with slower information processing and cognitive impairment.

Before you rush to the vitamin aisle, though, a word of caution: Vitamin D can be toxic in high doses. Because everyone’s needs and tolerance levels will be different, it may be wise to talk with your doctor or even have your blood levels tested before adding too many IUs to your daily intake.

Words by Matt Lupo