FAT-SOLUBLE VITAMIN SYNERGY (A, D, E, K)
30-day supply
Key Benefits
Supports immune strength, bone density, and cell protection
Supports bone health with synergistic vitamin D and K
Promotes immune function and antioxidant protection
Supports cardiovascular and vision health
Wellness Goals
Recommended Dose
5,000 IU (125mcg)
Take one capsule daily with a fat-containing meal for optimal absorption. All four vitamins in this complex are fat-soluble, meaning they need dietary fat to be properly absorbed. Taking with a meal containing olive oil, avocado, or nuts is ideal.
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The Details
Fat-soluble vitamins don't work alone — they form a team where each member enhances the others. Vitamin D helps your body absorb calcium, but it's vitamin K2 that directs that calcium into your bones and teeth (instead of depositing it in your arteries). Vitamin A supports immune cell maturation that vitamin D initiates. Vitamin E provides antioxidant protection that preserves vitamin A from oxidative degradation.
Taking vitamin D in isolation — which millions of people do — can actually create imbalances. High-dose vitamin D without adequate K2 may contribute to arterial calcification. Without sufficient vitamin A, vitamin D's immune benefits are incomplete. This complex provides all four fat-soluble vitamins in balanced, complementary ratios.
This is particularly important given that vitamin D deficiency affects an estimated 40-50% of the global population, vitamin K2 deficiency is nearly universal in Western diets, and vitamin A from retinol (the active form) is often inadequate in people who don't eat liver regularly. This complex addresses all four deficiencies simultaneously, the way nature intended.
Research
Key studies supporting D Complex, from peer-reviewed journals.
Efficacy of vitamin D3 supplementation on cancer mortality: systematic review and individual patient data meta-analysis — 2023
Study titles are simplified for readability. Provided for informational purposes — not medical advice.
Transparency
Every batch is independently tested by ISO-17025 accredited labs for purity, potency, and contaminants.
Designed by healthcare professionals using evidence-based research and clinical expertise.
Manufactured in cGMP & UL certified, FDA-registered facilities with a flawless inspection record.
Important Information
Contraindications
If you take blood-thinning medication (especially warfarin), consult your healthcare provider before use, as vitamin K affects blood clotting.
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
Really good supplement brand. The daily pack format is so convenient and I've been 100% consistent because of it. The quiz was genuinely thorough. Knocked one star off because I'd love the option to add or remove individual supplements as I learn more about my body.
I've tried so many supplements and honestly nothing has worked like this. The quiz is actually thorough and the results show it. Energy is UP, recovery is UP, sleep is SO much better. Can't believe it took me this long to find this brand.
Three weeks in and I already feel the difference. My morning energy is COMPLETELY different. No more dragging myself out of bed. The personalization through the quiz is what makes it work — it's not just a generic multivitamin. Stack actually thought about what MY body needs.
I've been on a health optimization journey for about three years and have tried what feels like every supplement brand on the market. Most of them are either generic multivitamins dressed up in pretty packaging, or they're so specific that you need to be a nutritionist to understand what you're actually taking. Stack sits in a completely different category. The quiz is the first thing that impressed me. It asks genuinely intelligent questions — not just 'how old are you and what's your gender' but questions about your diet, your sleep patterns, your stress levels, your exercise frequency. It felt like a real consultation rather than a data collection exercise. The pack that arrived was clearly personalized to my answers. After six weeks, the improvements have been consistent and measurable: better sleep quality, more stable energy throughout the day, and noticeably faster recovery after my runs. My partner commented that I seemed more 'on' in the evenings rather than crashing after dinner. The daily pack format is brilliant for compliance — I've been 100% consistent because the habit is so frictionless. One pack, done, every morning. No bottles, no measuring, no forgetting half of them. Genuinely one of the best health investments I've made.
My focus at work has been sharper and I'm waking up without that groggy feeling I used to have every morning. Told two friends about Stack already. Customer support was also really helpful when I had a question about one of the ingredients.
honestly wasn't sure about it at first but three weeks in and i'm so glad i tried it. energy is way better, i'm sleeping properly for the first time in months. the quiz was really detailed which gave me confidence it was actually personalized. would 100% recommend.
Personalized 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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