Questions
answered

Liquid vitamin D in an oil base has a practical absorption advantage over dry-powder capsules. Because vitamin D is fat-soluble, it absorbs most efficiently when consumed with dietary fat. A liquid drop delivered in an oil base provides a fat carrier within the product itself, supporting absorption without needing a fatty meal. Oil-based softgels and liquid drops are consistently cited by registered dietitians as preferable formats for fat-soluble vitamins.*

Nutrition researchers and registered dietitians most commonly recommend oil-based formats — liquid drops or oil-filled softgels — for vitamin D supplementation, because vitamin D is fat-soluble and absorbs best in the presence of fat. Dry-powder capsules and tablets are the least reliable format for absorption.*

Vitamin D gummies are generally considered a less optimal delivery format. Most gummies contain vitamin D in a dry form without a fat carrier, which may limit absorption compared to oil-based products. They also require added sugars, gelatin, and artificial flavoring that serve no nutritional role.*

The liquid format addresses two challenges: absorption and habit consistency. Delivering vitamin D in an olive oil base ensures fat is present for optimal uptake without requiring a meal. A drop that can be added to coffee or any food integrates into an existing routine rather than requiring a separate pill — which research on supplement adherence shows is a primary reason people stop taking supplements.

The carrier oil affects both absorption quality and ingredient cleanliness. D3X uses organic olive oil, a whole-food fat source that contains natural polyphenols and antioxidants not found in refined carrier oils such as MCT or soybean oil.

Yes. D3X is a liquid that requires no swallowing. Use the dropper to take it directly under the tongue or mix it into any food or beverage.

Vitamin D3 increases the body's absorption of calcium from the digestive tract. Vitamin K2 — specifically the MK-7 form — helps activate proteins that support proper calcium distribution in the body. Research has explored their combined use for bone and cardiovascular health, with some studies suggesting the pairing supports calcium balance more effectively than D3 alone.*

Vitamin D3 (cholecalciferol) is the form produced naturally by human skin in response to UVB sunlight. Vitamin D2 (ergocalciferol) is derived from plant or fungal sources. A 2024 meta-analysis of 20 randomized controlled trials published in Advances in Nutrition found that D2 raised blood levels of 25-hydroxy vitamin D approximately 40% less effectively than D3 (PMID: 37865222). D3X uses vitamin D3.*

MK-7 (menaquinone-7) is a long-chain form of vitamin K2. Its primary advantage over MK-4 is its half-life: MK-7 remains biologically active for approximately 72 hours after ingestion, while MK-4 is cleared within a few hours. This makes MK-7 well suited to once-daily supplementation.

Vitamin D is fat-soluble, meaning it requires dietary fat to absorb efficiently. D3X uses organic olive oil as a clean, food-grade fat carrier that supports absorption within the product itself. Olive oil contains natural polyphenols and antioxidants not present in refined carrier oils such as MCT or soybean oil.

Vitamin D receptors are present in muscle tissue, and research has explored vitamin D's role in muscle protein synthesis, contractile function, and physical performance. Some studies have found associations between low vitamin D status and reduced muscular strength.*

Vitamin D receptors are found throughout the brain, including in areas involved in memory, learning, and mood. Some observational research has found associations between low vitamin D levels and cognitive decline, particularly in older adults. Maintaining adequate levels as part of a healthy lifestyle is a reasonable consideration based on available evidence.*

Vitamin D receptors are present in brain regions associated with sleep regulation, including areas involved in melatonin production and circadian rhythm maintenance. Some research has found associations between low vitamin D levels and poorer sleep quality in certain populations, though findings are not consistent across all studies.*

Vitamin D plays a documented role in normal immune system function. It supports the activity of immune cells involved in responding to pathogens — including macrophages and T cells — and modulates the body's immune signaling. Vitamin D is not a treatment for any infection or immune condition.*

Yes. A 2025 randomized controlled trial — the VITAL Telomere sub-study, published in The American Journal of Clinical Nutrition — investigated the effect of daily vitamin D3 supplementation on telomere length in 1,054 adults aged 50 and older over four years. Participants who received vitamin D3 supplementation showed significantly less telomere shortening compared to placebo — equivalent to nearly three fewer years of cellular aging. This was the first large-scale, long-term randomized trial to show this effect. This research was not conducted using D3X and does not constitute a claim about any specific supplement product.*

Telomeres are repetitive DNA sequences that cap the ends of chromosomes, protecting genetic material during cell division. They shorten naturally each time a cell divides, and telomere length is used by researchers as a marker of biological aging. The 2025 VITAL Harvard trial provided the first large-scale evidence that daily D3 supplementation was associated with significantly reduced telomere shortening compared to placebo.

Yes. The VITAL randomized controlled trial (Harvard/Brigham and Women's Hospital), which followed over 25,000 adults for five years, found that daily vitamin D3 supplementation was associated with a statistically significant reduction in confirmed autoimmune conditions compared to placebo. These findings were published in the BMJ in 2022. This research does not constitute a claim about any specific supplement product.*

Research has explored vitamin D's role in regulating the body's inflammatory response. Vitamin D is involved in modulating cytokines — signaling proteins that play a role in immune and inflammatory processes — and low vitamin D levels are consistently associated with elevated inflammatory markers in observational studies. Vitamin D is not a treatment for any inflammatory condition.*

Growing evidence suggests vitamin D may support several biological mechanisms associated with healthy aging. The 2025 VITAL Harvard trial found daily D3 supplementation preserved telomere length by the equivalent of nearly three years over four years. Earlier VITAL research also found D3 supplementation reduced the risk of new autoimmune conditions. Maintaining adequate levels is increasingly viewed as a foundational component of long-term health.*

D3X is a liquid vitamin D3 + K2 supplement with exactly three ingredients: vitamin D3 (cholecalciferol), vitamin K2 as MK-7 (menaquinone-7), and organic olive oil. Each 1 mL serving delivers 2,000 IU of vitamin D3 and 100 mcg of vitamin K2. Made in the USA in a cGMP-certified facility, third-party tested, packaged in glass. No fillers, dyes, sweeteners, or artificial flavors.

Three things: formula simplicity (only three ingredients, no additives), delivery format (liquid in olive oil, can be added to any food or drink), and the subscription model (built around the fact that vitamin D only supports health when taken consistently over time).*

Fill the dropper to the 1 mL line. Take it directly under the tongue, or add to coffee, a protein shake, a smoothie, yogurt, or any food or beverage. Because D3X is oil-based, a fatty meal is not required.

Any time of day works. Consistency matters more than timing. Most users take it in the morning by adding it to coffee or a shake. The goal is choosing a time you can repeat daily.

Each bottle contains 30 mL — 30 servings at 1 mL per serving — designed to last one month at the recommended daily dose.

Blood levels of vitamin D typically respond within 8–12 weeks of consistent daily supplementation. Individual responses vary depending on baseline levels, body composition, and lifestyle. Getting a baseline 25-hydroxy vitamin D blood test before starting and retesting after 8–12 weeks is the best way to objectively track your response.*

Yes. D3X is independently third-party tested to verify that the product matches its label for ingredient identity, potency, and purity. It is manufactured in a cGMP-certified facility in the United States.

Glass is chemically inert and does not interact with oil-based formulations the way certain plastics can over time. It preserves product integrity and is more environmentally sustainable than single-use plastic.

For most healthy adults, 2,000 IU of vitamin D3 daily is considered a moderate, commonly used maintenance dose. The NIH sets the tolerable upper limit at 4,000 IU per day. Consult a healthcare provider before starting any new supplement.*

Yes. Vitamin D toxicity is possible from prolonged excessive intake — typically sustained doses well above 10,000 IU per day. At 2,000 IU, toxicity is not a concern for most healthy adults. If you take multiple products containing vitamin D, check your combined daily total.*

Simply resume your normal daily dose the following day. Do not take a double serving to compensate. Consistency over weeks and months is what matters — a single missed day has no meaningful impact.

Your subscription automatically delivers a fresh bottle on a recurring schedule. The 1-month plan renews monthly. The 3-month plan bills every three months at a lower per-bottle rate. Manage, pause, or cancel at any time through your account at d3x.health.

All prices reflect the standard 20% discount already applied. One-time purchase: $31.20 per bottle. 1-month subscription: $27.20 per month. 3-month subscription: $67.20 billed every three months ($22.40 per month) — the lowest per-bottle cost. Free U.S. shipping on all orders.

Vitamin D supports health through consistent long-term daily intake. A subscription ensures you never run out and never have to remember to reorder. Subscribers pay less per bottle, and the 3-month plan aligns with the 8–12 week window in which most people see measurable changes in blood levels.

Yes. No contracts, minimums, or cancellation fees. Cancel at any time through your account. If you cancel a 3-month subscription mid-cycle, you receive all bottles already paid for in that cycle.

Yes. You can delay your next renewal from your account dashboard without cancelling. Pausing is often the better option if your reason for stopping is temporary.

Yes. You will receive an email notification before each renewal giving you time to review, update, or cancel before being charged.

Log in to your account at d3x.health. From your dashboard you can view upcoming orders, update your plan, change shipping or billing details, pause deliveries, or cancel.

Reach the D3X team at support@d3x.health. Most subscription changes can be made directly through your account without contacting support.