What are some of the negative side effects of Vitamin D deficiency? Oooh, that’s an interesting question, and one that I have been interested in for years, long before my relationship with Athletic Greens began and long before Athletic Greens began that special offer of a one year free supply of Vitamin D and K2 for my friends (quick side note, that combination of D3+K2 is a powerful combination and helps maximize efficiency). We need Vitamin D for healthy bones as our bodies can only absorb calcium when there is Vitamin D also present in our bodies. So a negative side effect would be that we are putting our bone density at risk by not giving our bodies the opportunity to be able to absorb calcium. Especially if there is a chance that RED-S (Relative Energy Deficiency in Sport) is present, we are putting our bones under a lot of stress. Beyond that, Vitamin D helps support our immune system, which helps us fight off sickness and be able to handle our training better. While I don’t have any science to back it up, a lot of runner friends I know who have been feeling extreme fatigue and struggling in workouts have ended up getting bloodwork done and found they had low Vitamin D levels. All of those things sound important enough to me to prioritize it! In the summer, we can get it easier from the sun, but in the winter months, we may need a supplement to support us (which again, is why I love that AG1 Vit D+K2 which is in an olive oil blend, so it absorbs easily). Thanks for listening! We know there are so many podcasts you could listen to, and we’re honored you have chosen Running For Real.  If you appreciate the work that we do, here are a few things you can do to support us: Take a screenshot of the episode, and share it with your friends, family, and community on social media, especially if you feel that the topic will resonate with them.  Be sure to tag us on Twitter, Facebook, Instagram  Leave an honest review on iTunes or your favorite podcast player. Your ratings and reviews will really help us grow and reach new people. Not sure how to leave a review or subscribe?  You can find out here. Thank you for listening; we look forward to hearing your thoughts!