Is Vitamin D really as essential as everyone says or are we just overhyping another supplement?

After getting tons of questions following our popular creatine episode, we realized people are equally confused about Vitamin D. So in this one, we’re breaking it all down: what Vitamin D actually is, where it comes from, who’s most at risk for deficiency, and how it’s connected to things like bone health, mood, immune function, and even PCOS.

By the end of this episode, you’ll know if Vitamin D matters for you, what dose is right, and why sunlight might not be enough based on your lifestyle.

🎗️Timestamps:

00:30 Hosts Catching Up: Yawning & Sleep Deprivation
02:27 Revisiting the Creatine Episode
05:00 What to Expect in This Episode (Overview of Key Points)
05:53 What Is Vitamin D & the Difference Between D2 and D3
07:03 How Vitamin D Impacts Bone Health
09:45 Pros, Cons & Where to Actually Get Vitamin D
11:00 Common Misconceptions About Sunlight & Vitamin D
12:37 Dietary Sources & Fortified Foods with Vitamin D
17:28 How Obesity, Breastfeeding & Digestive Disorders Affect Vitamin D
19:57 Navigating Conflicting Research on Vitamin D
24:58 Immunity, Respiratory Illness & the COVID Controversy
30:50 Mental Health, Seasonal Affective Disorder & Vitamin D
36:50 New 2025 Research: Vitamin D’s Role in Managing PCOS
39:46 Final Takeaways

📒 Resources:

🎧 50 | Everything We’ve Learned About Creatine (So You Don’t Have To)
🎧 40 | Scandals in the Supplement Space
📱 @pcosnutrition on Instagram
📄 Center for Health Research — Vitamin D Potency Varies Widely in Dietary Supplements
📄 National Institute for Health and Care Excellence — Vitamin D: supplement use in specific population groups
📄 Scientific Advisory Committee on Nutrition — Vitamin D and Health Report
📄 Martineau et al., BMJ 2017 — Vitamin D supplementation to prevent acute respiratory tract infections
📄 Callegari et al., JAMA Psychiatry 2024 — Vitamin D supplementation and depression meta-analysis
📄 Parliamentary Office of Science and Technology 2021 — Vitamin D and COVID-19
📄 National Library of Medicine — Effects of

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🟡 How to: Fitness
Instagram: @howtofitnesspod

🟡 Michael Ulloa
Website: michaelulloa.com
Instagram: @michaelulloapt

🟡 Kate Lyman
Website: katelymannutrition.com
Instagram: @klnutrition

Thank you for listening to the How to: Fitness Podcast with Michael Ulloa and Kate Lyman!