D3X · The Science

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Research on Vitamin D: insufficiency, absorption, sleep, mood, performance, longevity. Every claim tied to a published study.

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Is 1,000 IU of Vitamin D Enough? When It Is and When It Isn't

1,000 IU is one of the most common vitamin D doses on the shelf. It covers the RDA, but whether it's enough depends on where you start. Who...

5 min read · Nov 2026 dosage

Vitamin D IU to mcg (and mcg to IU): Conversion Chart

Your bottle says 50 mcg, your doctor said 2,000 IU, and a forum post says 5,000 mg. One vitamin, three units. Here's the conversion chart, why labels switched...

5 min read · Nov 2026 low

At-Home Vitamin D Tests: Do They Work, and Which Kind to Buy?

Doctors rarely test healthy adults for vitamin D, so most people who are low never find out. At-home tests fill the gap, but there are two very different...

5 min read · Nov 2026
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68 articles, newest first

dosage Is 1,000 IU of Vitamin D Enough? When It Is and When It Isn't Nov 2026 dosage Vitamin D IU to mcg (and mcg to IU): Conversion Chart Nov 2026 low At-Home Vitamin D Tests: Do They Work, and Which Kind to Buy? Nov 2026 low Does Vitamin D Help You Tan? And Does a Tan Help Your Vitamin D? Nov 2026 timing Does Vitamin D Give You Vivid Dreams? Nov 2026 fitness Does Vitamin D Help Your Golf Game? Nov 2026 low Which Supplements Have the Most Science Behind Them? 6 Ranked Nov 2026 ingredients Best Vitamin D for Seniors: What Changes After 60, and What to Take Oct 2026 dosage Vitamin D 2,000 IU vs 5,000 IU: Which Should You Take? Oct 2026 ingredients Best Vitamin D Supplement for Women: What to Look For at 30, 40, 50 and Beyond Oct 2026 ingredients What Does Liquid Vitamin D Taste Like? Oct 2026 timing Can You Mix Vitamin D Drops Into Food, Smoothies and Shakes? Oct 2026 ingredients How Long Does Liquid Vitamin D Last After Opening? Oct 2026 timing Does Vitamin D Break a Fast? Oct 2026 ingredients Best Liquid Vitamin D3 + K2 Drops: What to Look For Oct 2026 safety Is 2,000 IU of Vitamin D3 a Day Safe? Oct 2026 timing Does a Sunny Winter Vacation Boost Your Vitamin D? Sep 2026 low Do SAD Lamps Give You Vitamin D? Sep 2026 absorption Vitamin D If You Can't Swallow Pills: Your Best Options Sep 2026 timing Can You Take Vitamin D With Coffee? Sep 2026 low Do GLP-1 Users Need Vitamin D? Why Ozempic and Mounjaro Users Run Low Sep 2026 fitness Vitamin D and Weight Loss: What the Research Shows Sep 2026 safety What Not to Take With Vitamin D Sep 2026 timing How Long Does Vitamin D Take to Work, and How Long Do You Keep Taking It? Sep 2026 absorption Vitamin D Drops vs Spray: Which Absorbs Better? Sep 2026 ingredients Is Vitamin D3 Vegan? Lichen vs Lanolin Sep 2026 absorption What's the Best Carrier Oil for Vitamin D? Sep 2026 dosage Is the Vitamin D in Your Multivitamin Enough? Sep 2026 k2 Vitamin D3 and K2: Why Take Them Together, How Much, and Who Shouldn't Sep 2026 timing When Should You Start Taking Vitamin D for Winter? Sep 2026 low What Causes Vitamin D Deficiency? Sep 2026 low Vitamin D Blood Test: What the Numbers Mean and What to Do If It's Low Sep 2026 health Does Vitamin D Do Anything For Your Immune System? Sep 2026 dosage Vitamin D Daily vs Weekly: Which Dosing Schedule Works Better? Sep 2026 absorption Vitamin D Gummies: Do They Work, and Are They Better Than Drops? Sep 2026 low Do You Need Vitamin D In The Summer? Aug 2026 absorption Why Does Your Vitamin D Keep Dropping? 6 Reasons Levels Won't Hold Aug 2026 safety Can You Take Too Much Vitamin D? Aug 2026 absorption Calcium and Vitamin D Supplements: Do You Need Both, and Where Does K2 Fit? Aug 2026 fitness You train five days and you're still probably low Aug 2026 timing Vitamin D and Magnesium: Can You Take Them Together, Which Magnesium, and When? Aug 2026 health Vitamin D Supplements for Hair Loss: What the Research Shows (and Doesn't) Aug 2026 dosage What 50,000 IU of Vitamin D Is Actually For Aug 2026 health Vitamin D, Muscle, and Metabolism for Women Over 40 Aug 2026 fitness Vitamin D: Injury Risk and Missed Training Aug 2026 k2 Does K2 Actually Improve Bone Density? Aug 2026 k2 MK-7 vs MK-4: Which Form of K2 Should You Take? Aug 2026 health Vitamin D and Hashimoto's: Antibodies, Testing, and what the Evidence shows Jul 2026 safety Does Vitamin D Cause Constipation? What the Research Says Jul 2026 health Why Vitamin D Is Crucial for Women Over 40 Jul 2026 timing Why Consistency Is the Hard Part of Vitamin D Jun 2026 ingredients What's Actually in Your Vitamin D Supplement Jun 2026 health Can You Get Enough Vitamin D From the Sun? Jun 2026 absorption Liquid vs Capsule Vitamin D Jun 2026 timing Best Time to Take Vitamin D: Morning or Night, With or Without Food Jun 2026 low Signs of Vitamin D Deficiency: Symptoms to Watch For and When to Test Jun 2026 dosage How Much Vitamin D Should You Take? Jun 2026 absorption Vitamin D3 vs D2: Which Is Better, and Is Vitamin D the Same as D3? Jun 2026 ingredients Best Vitamin D Supplement: How to Choose Drops, Softgels, Gummies or Tablets Jun 2026 health Does Vitamin D Increase Testosterone? What the Trials Show Jun 2026 health What Vitamin D has to do with Cortisol Jun 2026 health What Vitamin D at 39 Predicted About Brains 16 Years Later May 2026 health What a Four-Year Vitamin D Trial Found About Aging May 2026 health Vitamin D And Sleep: What The Research Shows May 2026 absorption Why Vitamin D Needs Fat To Be Absorbed May 2026 health Why Vitamin D Matters For Men Under 35 Apr 2026 low Why 70% Of Americans Are Low On Vitamin D Mar 2026 low Why Modern Life Lowers Your Vitamin D Mar 2026
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