Get Free Weekly Health Tips from Dr. Hyman Sign Up For Dr. Hyman’s Weekly Longevity Journal Get ad-free episodes & Dr. Hyman+ audio exclusives In the US alone, 70% of Americans have either deficient or suboptimal levels of vitamin D. This is a massive problem given vitamin D's impact on our health and its effects on our gene regulation and expression. Vitamin D also regulates calcium and supports the functioning of the immune system, making it one of the most important biological compounds in the body.  In today’s episode of a new series I’m calling Know Your Numbers, I dive deep into vitamin D. I discuss why vitamin D deficiency is a problem, how conventional medicine misses the mark in measuring vitamin D levels, how Functional Medicine treats vitamin D deficiency, and much more. You can test your vitamin D levels with Function Health, a company I co-founded. It has been a lifelong dream for me. Function is the first-ever membership that includes 100+ lab tests and personalized insights from globally renowned doctors based on your results. Join Function at FunctionHealth.com. This episode is brought to you by Mitopure and AG1. Support essential mitochondrial health and save 10% on Mitopure. Visit TimelineNutrition.com/Drhyman and use code DRHYMAN10. Get your daily serving of vitamins, minerals, adaptogens, and more with AG1. Head to DrinkAG1.com/Hyman and get 10 FREE travel packs with your first order.  Here are more details from the episode (audio version / Apple Subscriber version): Why vitamin D deficiency is a problem (5:49 / 3:31) What is vitamin D and what does it do in the body? (6:24 / 4:06) “Normal” vs. optimal vitamin D references ranges (9:03 / 6:45) How much vitamin D should you take? (15:06 / 12:48) Root causes of low levels of vitamin D (17:23 / 15:05) Testing your vitamin D with the 25-hydroxy vitamin D3 test (26:04 / 23:46) Symptoms of and diseases associated with vitamin D deficiency (26:27 / 24:09) Addressing vitamin D deficiency with diet, lifestyle and supplementation (42:53 / 40:35) References for research mentioned in this episode can be found here. Learn more about your ad choices. Visit megaphone.fm/adchoices