Vitamin D3
foundation
Vitamin D is a fat-soluble vitamin your skin produces from sunlight, but it functions more like a hormone than a traditional vitamin. It influences over 1,000 genes and plays roles in immune function, bone health, mood regulation, and hormone production — with vitamin D receptors found throughout the body, including in testicular tissue. Deficiency is remarkably common among men who work indoors, live in northern latitudes, or simply spend most of their time out of direct sun.
We include vitamin D3 (cholecalciferol) — the same form your body naturally produces from sun exposure and the most effective form for raising blood levels. At 75mcg (3,000 IU), we provide a meaningful daily dose for men who don't get regular sun exposure.
The statements on this page have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
Vitamin D3 Benefits — What Studies Found
Modern life keeps you indoors, and the deficit shows up everywhere — hormones, mood, immunity. Vitamin D helps close the gap most men don’t realize they have.
Testosterone in Deficient Men
Testosterone (Deficient)Immune Defense
Infection RiskHormonal Regulator
Genes RegulatedWhy a 75mcg (3,000 IU) dose of Vitamin D3
The daily value for vitamin D is 20mcg (800 IU), but this represents a minimum to prevent severe deficiency, not an optimal intake.
- Meaningful Daily Dose 75mcg (3,000 IU) sits within the clinical study range for adults without adequate sun exposure, and stays at or below the tolerable upper intake level for everyday use.
- D3 Cholecalciferol Form The same form your body produces from sunlight and the most effective at raising blood levels.
- Addresses a Common Gap Most men who work indoors or live in northern latitudes fall short on vitamin D, which may affect testosterone, immunity, and mood.
- Backed by Extensive Research One of the most studied nutrients, with over 260 clinical trials supporting its roles across multiple body systems.
Note on individual variation: Some people may need more or less depending on their baseline levels, sun exposure, skin pigmentation, body composition, and other factors. If you're concerned about your vitamin D status, blood testing can provide clarity.
Therapeutic Dose Range
Clinical studies use 25–125mcg (1,000–5,000 IU) daily. Our 75mcg (3,000 IU) provides a meaningful dose for those without adequate sun exposure.
A vitamin that functions like a hormone, influencing over a thousand genes — with receptors all the way down to testicular tissue.
01
Immune Support
Martineau AR, et al. (2019). Health Technology Assessment.
Source
Immune Support
Martineau AR, et al. (2019). Health Technology Assessment. Source
A major meta-analysis of individual participant data (n=10,933 across 25 RCTs) found that vitamin D supplementation reduces acute respiratory infection risk by 12% overall, and by 70% in severely deficient individuals. Regular daily/weekly dosing was more effective than large, infrequent doses.
02
Testosterone in Deficient Men
Pilz S, et al. (2011). Hormone and Metabolic Research.
Source
Testosterone in Deficient Men
Pilz S, et al. (2011). Hormone and Metabolic Research. Source
In a year-long randomized controlled trial, men with vitamin D deficiency who took vitamin D supplements showed significant increases in total testosterone, bioactive testosterone, and free testosterone compared to placebo. The effect was specifically seen in men who started with low vitamin D. The nuance that keeps this honest: supplementation restores testosterone when you start deficient - it does not push a normal level higher (RCTs in already-replete men are null). Essential to have enough; not a booster beyond that.
03
Athletic Recovery
Mielgo-Ayuso J, et al. (2018). Nutrients.
Source
Athletic Recovery
Mielgo-Ayuso J, et al. (2018). Nutrients. Source
Elite male rowers supplementing with vitamin D3 (3,000 IU/day for 8 weeks) preserved hematological markers associated with recovery — hemoglobin, hematocrit, and transferrin all improved vs controls who declined. Serum vitamin D levels correlated with testosterone and cortisol levels, though supplementation did not significantly change hormone levels directly.
04
Gene Regulation
Pike JW, Meyer MB. (2010). Endocrinology and Metabolism Clinics of North America.
Source
Gene Regulation
Pike JW, Meyer MB. (2010). Endocrinology and Metabolism Clinics of North America. Source
Vitamin D exerts effects by binding to and activating the vitamin D receptor (VDR), which regulates the activity of over 1,000 different genes. This explains its wide-ranging effects throughout the body.
05
Vitamin D Is Causally Linked to Testosterone
Chen C, et al. (2019). Causal Link Between Vitamin D and Total Testosterone in Men: A Mendelian Randomization Analysis. J Clin Endocrinol Metab.
Source
Vitamin D Is Causally Linked to Testosterone
Chen C, et al. (2019). Causal Link Between Vitamin D and Total Testosterone in Men: A Mendelian Randomization Analysis. J Clin Endocrinol Metab. Source
A Mendelian-randomization study - a genetic design built to test causation rather than correlation - found that vitamin D has a causal effect on total testosterone in men (Chen et al., 2019). This is why adequate vitamin D is considered essential for normal testosterone regulation, and why a deficiency drags it down.
06
Mood Support
Vitamin D protects against depression: umbrella meta-analysis (2023).
Source
Mood Support
Vitamin D protects against depression: umbrella meta-analysis (2023). Source
An umbrella meta-analysis pooling ten separate RCT meta-analyses found vitamin D supplementation significantly reduced depressive symptoms versus placebo (pooled SMD -0.40), with the clearest effects when correcting a deficiency.
Published Research
297 studiesEvery claim we make is grounded in peer-reviewed research. Tap any study to read the abstract.
Our Assessment: Vitamin D3
One of the most studied nutrients in existence. Deficiency is common and correcting it improves immune function, bone health, and testosterone in deficient men. Effects are most meaningful when you're actually low.
- Vitamin D deficiency is extremely common and well-documented
- Immune function benefits are supported by high-quality meta-analyses
- Bone health benefits are established
- Testosterone effects are demonstrated in deficient men
- The mechanism (VDR activation, gene regulation) is understood
- Testosterone effects appear specific to men who are deficient
- Benefits for mood and depression are inconsistent in research
- Optimal blood levels are still debated (though deficiency thresholds are clear)
- Very high doses over extended periods can cause problems
How Vitamin D3 Fits the Formula
No ingredient works alone. Vitamin D3 was chosen because it amplifies — and is amplified by — specific formula partners.
Tongkat Ali & Fenugreek
Vitamin D receptors exist in testicular tissue, and deficiency is associated with lower testosterone levels. Tongkat ali and fenugreek support testosterone through separate pathways. Addressing vitamin D status alongside these herbs means covering more of the factors that influence testosterone levels.
Zinc
Both vitamin D and zinc are common deficiencies that affect testosterone production. Addressing both simultaneously covers two potential bottlenecks — zinc supports testosterone synthesis directly, while vitamin D supports the broader hormonal environment.
Boron
Vitamin D and boron both support the hormonal environment through different pathways — vitamin D through receptor-level signaling, boron through its effects on free testosterone and estradiol. Both also influence mineral metabolism, making them complementary in a formula focused on men's health foundations.
Safety and Precautions
Always consult with a healthcare professional before starting any new dietary supplement, especially if you have an existing medical condition or take prescription medications.
