What does Vitamin D do in the body?

Vitamin D is a fat-soluble nutrient that supports various functions in the body. It plays a role in maintaining normal muscle function, immune system support, and overall wellness. Vitamin D also interacts with receptors throughout the body and acts more like a hormone than a vitamin, which is why it's often discussed in relation to energy, mood, and daily performance.

Time to get
serious
about your D

Premium liquid D3 + K2 drops in organic olive oil. In a glass bottle, not plastic. Only three ingredients, no fillers, sugar, dyes, or artificial anything. The only Vitamin D-focused brand, with the education, reminders, and subscription to help you stick with it.

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2000 IU · D3 + K2 MADE IN USA

Made in USA

Third-Party Tested

cGMP Facility

3 Ingredients

No Sweeteners

Olive Oil Base

Made in USA

Third-Party Tested

cGMP Facility

3 Ingredients

No Sweeteners

Olive Oil Base

70^%1

of Americans are
low on Vitamin D

Research describes Vitamin D deficiency as the most widespread nutritional deficiency worldwide.2 Most brands see a market. We see a problem to solve, and we're built entirely around fixing it.

Why it happens

Indoor lifestyles, poor diets, seasons, geography, sunscreen use, and inconsistent sun exposure.

Why it's missed

Vitamin D isn't routinely tested for, so many don't connect their symptoms to being low.

Why it matters

Vitamin D acts more like a hormone than a vitamin, influencing gene-related processes throughout the body.2 It plays a key role in helping your body function the way it's supposed to.*

Only three
simple
ingredients

No dyes. No sweeteners. No proprietary blends. No fillers. Just the three things that matter.

Vitamin D3

The main event

The star of D3X. It behaves more like a hormone than a typical vitamin and influences a wide range of processes in the body.2* We use D3 because it's the form your body naturally makes from sunlight, and it's generally more effective than D2 at raising and maintaining Vitamin D levels.3*

2000 IU per serving · As cholecalciferol

Vitamin K2

Helps D3 work cleanly

Helps D3 do its job cleanly. D3 helps your body absorb and use calcium, and K2 helps guide where that calcium gets utilized, supporting proper distribution and balance.5* We chose MK-7 because it stays active longer than other forms,4 making it a better fit for consistent daily use.

100 mcg · MK-7 (Menaquinone-7)

Organic Olive Oil

The clean carrier

Vitamin D is fat-soluble, so it absorbs best with fat. We use olive oil as a clean, food-based carrier that's naturally rich in antioxidants. A better choice than processed oils or fillers.

Certified Organic · Cold-pressed

That's it. · No artificial anything

Three things
set us apart

D3X is a premium liquid Vitamin D3 + K2 supplement made with three ingredients in an organic olive oil base, packaged in glass and built around helping people stay consistent with their daily Vitamin D intake.

What's in the bottle

Olive oil base, glass bottle, three ingredients. No seed oils, no fillers, no sweeteners, no proprietary blends.

What we make

One product, done right. Vitamin D is the entire company. Every decision built around it.

After you buy

An educational pamphlet in every box, daily ritual messaging, and a subscription cadence built around the habit. Our job is helping you actually take it.

2000

IU Vitamin D3

Servings / Month

1 mL

Daily Dropper

Sweeteners

Four things
that actually
matter

Sleep

Supports better recovery and more consistent sleep quality over time.6*

Mood

Supports brain health pathways tied to mood and baseline wellbeing.7*

Performance

Supports muscle function, recovery, and physical performance.8*

Focus

Supports neurological function related to clarity and concentration.9*

A habit that
actually sticks

Add 1 mL to your day

Into your beverage of choice, food, or directly under your tongue. Takes three seconds.

Take daily

Same time each day is best for habit building. Pair it with your morning coffee, your protein shake, or whatever routine you already have.

Reassess after 8 to 12 weeks

The best results come from consistency. Give it a full cycle and notice the difference in how you feel.

Stop paying for
overpriced hype

Most supplement routines cut corners with weaker forms, extra fillers, poor absorption, or formats that don't fit into daily life. Here's what a typical month looks like.

Green powders

$80

per month

Greens gummies

$80

per month

Premium probiotics

$80

per month

Nootropics

$80

per month

Electrolytes

$50

per month

D3XSave $8.80 / bottle

$22.40

per bottle · 3-month sub

"I wasn't sleeping well. My energy was off. I didn't feel like myself. Turns out I was deficient. Once I started looking, I realized how common it is."

Tim, one of our founders, didn't set out to start a supplement company. He was dealing with symptoms he couldn't really explain: low energy, sleep that wasn't quite right, and not feeling like he was performing at his best.

After getting bloodwork done, he found out he was Vitamin D deficient. Once he started looking into it, he realized how widespread Vitamin D insufficiency is, and how many people walk around with it without ever thinking to test. That's why D3X was founded: to tackle a prevalent issue hiding in plain sight.

TimFounder, D3X

No hype.
Just research.

Research

Key Vitamin D Benefits You Should Know

→

Research

The Global Vitamin D Deficiency Crisis

→

Research

How Modern Life Is Fueling the Deficiency Crisis

→

The Science →

Questions
worth asking

What is D3X?

D3X is a premium liquid Vitamin D3 + K2 supplement made with three ingredients (Vitamin D3, Vitamin K2 as MK-7, and organic olive oil), packaged in a glass bottle with a 1 mL dropper. Each bottle contains 30 daily servings of 2000 IU Vitamin D3 and 100 mcg Vitamin K2. Made in the USA in a cGMP facility and third-party tested.

How is D3X different from other Vitamin D supplements?

Three things set D3X apart. First, what's in the bottle: an olive oil base, a glass bottle, three ingredients, with no seed oils, fillers, sweeteners, or proprietary blends. Second, what we make: one product. Vitamin D is the entire company, not a line item among hundreds. Third, what happens after you buy: an educational pamphlet in every box, daily ritual messaging, and a subscription cadence built around the habit.

How common is Vitamin D insufficiency?

Vitamin D insufficiency is widespread, especially among people who get limited sunlight, live in urban areas, or spend most of their time indoors.2 Even with a healthy diet, many individuals may not get enough Vitamin D from food or sun exposure alone.* D3X focuses on daily consistency to help fill common nutritional gaps.*

What is Vitamin D and what does it do?

Vitamin D is a fat-soluble nutrient that supports various functions in the body.* It plays a role in maintaining normal muscle function, immune system support, and overall wellness.2* Vitamin D also interacts with receptors throughout the body, which is why it's often discussed in relation to energy, mood, and daily performance.* D3X is formulated to make Vitamin D intake simple and consistent, especially for individuals with limited sun exposure or indoor lifestyles.*

What are common signs of low Vitamin D?

Low Vitamin D levels may be associated with general fatigue, reduced motivation, or changes in mood or focus in some individuals.* These experiences are nonspecific and can result from a variety of factors. It's important to talk to a healthcare provider to better understand your individual health needs.

Can you get enough Vitamin D from sunlight alone?

Sunlight is a natural source of Vitamin D3, produced by the skin in response to UVB exposure.* However, factors like time of day, season, skin tone, geographic location, clothing, sunscreen use, and time spent indoors can limit how much Vitamin D your body produces.10* Many people use supplements like D3X to support their Vitamin D levels consistently throughout the year.*

How is D3X different from a multivitamin?

Multivitamins spread small amounts across dozens of ingredients. D3X focuses on the one thing most people are actually missing, in a liquid format built for daily consistency, not pill fatigue.

Sources

Every health claim on this page is backed by peer-reviewed research. Tap any reference to read the original study.

1

Vitamin D deficiency and insufficiency among US adults: prevalence, predictors and clinical implications

British Journal of Nutrition · 2018
View study →
2

Vitamin D Deficiency

Holick MF · New England Journal of Medicine · 2007
View study →
3

Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis

Tripkovic et al. · American Journal of Clinical Nutrition · 2012
View study →
4

MK-7 and Its Effects on Bone Quality and Strength

Sato et al. · Nutrients · 2020
View study →
5

Dietary intake of menaquinone is associated with a reduced risk of coronary heart disease: the Rotterdam Study

Geleijnse et al. · Journal of Nutrition · 2004
View study →
6

Vitamin D Supplementation and Sleep: A Systematic Review and Meta-Analysis of Intervention Studies

Abboud · Nutrients · 2022
View study →
7

The effect of vitamin D supplementation on depression: a systematic review and dose-response meta-analysis of randomized controlled trials

Mikulska et al. · 2024 · 31 trials, 24,189 participants
View study →
8

Effect of vitamin D supplementation on upper and lower limb muscle strength and muscle power in athletes: A meta-analysis

Zhang et al. · PLOS ONE · 2019
View study →
9

A Systematic Review and Meta-Analysis of The Effect of Low Vitamin D on Cognition

Goodwill & Szoeke · Journal of the American Geriatrics Society · 2017
View study →
10

Sunlight and Vitamin D: A global perspective for health

Wacker & Holick · Dermato-Endocrinology · 2013
View study →