My evenings have completely changed
I used to be useless after 7pm. Now I have energy into the evenings and actually enjoy time with my family rather than just surviving until bedtime. Stack has genuinely changed my quality of life.
Nour M.
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Vitamin5,000 IU (125mcg)
Vitamin D3
THE SUNSHINE VITAMIN FOR BONES, IMMUNITY & MOOD
Dairy freeGluten freeSoy freeGMO free
$5.99/mo
30-day supply
Key Benefits
1
Supports calcium absorption and bone building
2
Promotes muscle strength and function
3
Supports immune health and cell-to-cell communication
4
Supports mood regulation and cognitive function
Wellness Goals
Recommended Dose
5,000 IU (125mcg)
Take one capsule daily with a fat-containing meal. Vitamin D is fat-soluble and requires dietary fat for absorption. For those with known deficiency, a healthcare provider may recommend higher doses initially. Getting your blood levels tested (25-hydroxyvitamin D) helps determine the right dose for you.
Get your personalized dose⚗️
3rd Party Tested
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Doctor Formulated
🛡️
cGMP Certified
The Details
Why you'll love it
Vitamin D is less of a vitamin and more of a hormone — and it influences the expression of over 1,000 genes in your body. Despite its critical importance, an estimated 42% of American adults are deficient, with rates even higher in people with darker skin tones, those who live in northern latitudes, and anyone who spends most of their time indoors.
The consequences of deficiency are far-reaching. Beyond its well-known role in calcium absorption and bone health, vitamin D is a key regulator of immune function. It activates your innate immune system's first responders (including antimicrobial peptides like cathelicidin) and helps modulate the adaptive immune response to prevent overreaction. Low vitamin D is consistently associated with increased susceptibility to respiratory infections.
Vitamin D also supports muscle strength (deficiency is linked to increased fall risk in older adults), mood regulation (low levels correlate with seasonal depression), and cardiovascular health. We use D3 (cholecalciferol), the same form your skin produces from sunlight, at 5,000 IU — a dose supported by research for achieving and maintaining optimal blood levels of 40-60 ng/mL.
Research
Clinical Evidence
Key studies supporting Vitamin D3, from peer-reviewed journals.
2
Vitamin D supplementation reduced cancer death risk by 13%
Association between vitamin D supplementation and mortality: systematic review and meta-analysis — 2019
3
Vitamin D supplements reduce symptoms of depression
The effect of vitamin D supplementation on depression: a systematic review and dose-response meta-analysis — 2024
Study titles are simplified for readability. Provided for informational purposes — not medical advice.
Transparency
What's Inside
Third-Party Tested
Every batch is independently tested by ISO-17025 accredited labs for purity, potency, and contaminants.
Doctor Formulated
Designed by healthcare professionals using evidence-based research and clinical expertise.
cGMP Certified
Manufactured in cGMP & UL certified, FDA-registered facilities with a flawless inspection record.
Important Information
Contraindications
- hypercalcemia
- sarcoidosis
Those with hypercalcemia, sarcoidosis, or granulomatous diseases should consult their healthcare provider before use. Have your vitamin D levels monitored if supplementing long-term at 5,000 IU.
As with any natural health product, consult your healthcare practitioner. Store in a cool, dry place. Keep out of reach of children. Discontinue use immediately if you experience an adverse event.
What people say
changed my whole routine tbh
used to take like 5 different supplements every morning and always forgot at least two of them. now i take one stack pack and that's it. so much simpler. and the results are actually better. wild.
Hazel B.
The value proposition is actually excellent
I calculated what I was spending on separate supplements, gym supplements, and energy drinks before Stack.
Tim A.
Simple, smart, and it actually works
The packaging is some of the nicest I've seen in wellness. But beyond aesthetics, the product delivers. My energy throughout the day is more stable and I'm recovering faster from workouts. I was genuinely skeptical.
Ashley N.
The inflammation reduction has been significant
I suffer from low-grade chronic inflammation and it affects everything - energy, mood, joint comfort. Stack's personalized formula has noticeably reduced these symptoms over three months. The targeted approach is clearly more effective than generic options.
Eric T.
My husband noticed before I did
About six weeks in my husband said I seemed more like myself - more energy in the evenings, less irritable, sleeping better. I hadn't even consciously registered how much had changed until he said it.
Amara S.
Personalized for you
Not sure if Vitamin D3 is right for you?
Take our 2-minute Health Assessment and let our AI build your personalized stack — every supplement chosen for your specific goals.
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