Vitamin D is essential for men's health, functioning as both a vitamin and hormone with wide-ranging effects throughout the body. Whilst best known for supporting bone health, vitamin D benefits for men extend to muscle function, immune regulation, and potentially cardiovascular and reproductive health. In the UK, deficiency is common, particularly during autumn and winter when sunlight exposure is limited. Men with darker skin, those who work indoors, or individuals who cover their skin face elevated risk. Understanding how to maintain adequate vitamin D levels through sunlight, diet, and supplementation is crucial for optimising health across the lifespan.

What Is Vitamin D and Why Do Men Need It?

Vitamin D is a fat-soluble vitamin that acts as a hormone in the body and plays a crucial role in numerous physiological processes. Unlike most vitamins, it can be synthesised by the skin when exposed to ultraviolet B (UVB) radiation from sunlight, though it can also be obtained through dietary sources and supplements. Once produced or consumed, vitamin D undergoes conversion in the liver and kidneys to its active form, calcitriol (1,25-dihydroxyvitamin D), which then exerts its effects on target tissues.

For men specifically, maintaining adequate vitamin D levels is important due to its involvement in several health concerns. Vitamin D receptors are widely expressed throughout the body, including in bone, muscle, immune cells, and reproductive tissues such as the testes and prostate. This distribution reflects the vitamin's diverse physiological roles, from supporting bone mineralisation and immune function to potentially influencing testosterone production and cardiovascular health.

In the UK, vitamin D deficiency is common, particularly during the autumn and winter months when sunlight exposure is limited. Men who have little sun exposure (such as those who work indoors or are housebound), have darker skin pigmentation, or cover most of their skin when outdoors face an elevated risk of deficiency. The consequences of inadequate vitamin D status can include reduced bone density and increased fracture risk, with potential impacts on muscle function and overall wellbeing. Understanding the importance of this essential nutrient is the first step towards optimising men's health across the lifespan.

Key Health Benefits of Vitamin D for Men

Bone and Musculoskeletal Health

Vitamin D's most well-established role is in calcium homeostasis and bone metabolism. It enhances intestinal absorption of calcium and phosphate, minerals essential for bone mineralisation. In men, adequate vitamin D status helps maintain bone density and may reduce the risk of osteoporosis and fractures, particularly when combined with sufficient calcium intake. The evidence for fracture prevention is strongest in those with confirmed vitamin D deficiency or those at higher risk. Research indicates that men with vitamin D deficiency have lower bone mineral density, which may contribute to increased fracture risk, particularly in later life.

Testosterone and Reproductive Health

Emerging evidence suggests a relationship between vitamin D status and testosterone levels in men, though the exact nature of this association remains under investigation. Some observational studies have found correlations between higher vitamin D levels and increased testosterone concentrations, whilst vitamin D receptors have been identified in testicular tissue. However, there is no official link definitively established, and intervention studies have produced mixed results. Men concerned about testosterone levels should discuss comprehensive evaluation with their GP rather than relying solely on vitamin D supplementation.

Cardiovascular and Metabolic Health

Vitamin D may play a role in cardiovascular health through multiple mechanisms, including regulation of blood pressure, vascular function, and inflammation. Observational data suggest associations between vitamin D deficiency and increased risk of hypertension, heart disease, and type 2 diabetes in men. The vitamin appears to influence insulin secretion and sensitivity, potentially affecting glucose metabolism. Whilst these associations are compelling, current evidence does not conclusively prove causation, and NICE does not recommend vitamin D supplementation specifically for cardiovascular disease or diabetes prevention.

Immune Function and Mental Wellbeing

Vitamin D modulates both innate and adaptive immune responses, with mechanistic studies suggesting potential effects on immune regulation. Additionally, vitamin D receptors are present in brain regions involved in mood regulation, and some research has explored links between deficiency and depression, though findings remain inconclusive. Men experiencing persistent low mood should seek medical evaluation rather than self-treating with supplements alone.

How Much Vitamin D Do Men Need Daily?

The UK government, following advice from the Scientific Advisory Committee on Nutrition (SACN), recommends that all adults, including men, should consider taking a daily supplement containing 10 micrograms (400 IU) of vitamin D during autumn and winter months (October to March). This recommendation applies to the general population to maintain bone and muscle health.

For men at higher risk of deficiency—including those with limited sun exposure (such as those who are housebound or in care homes), those with darker skin tones (African, African-Caribbean, or South Asian backgrounds), or those who cover their skin for cultural or religious reasons—year-round supplementation is advised.

Therapeutic doses for treating confirmed vitamin D deficiency are considerably higher and should only be taken under medical supervision. NICE guidance suggests loading doses followed by maintenance therapy for individuals with documented deficiency (serum 25-hydroxyvitamin D levels below 25 nmol/L). These treatment regimens typically involve a total loading dose of approximately 300,000 IU over 6-10 weeks (e.g., 50,000 IU weekly for 6 weeks or 20,000 IU twice weekly for 7 weeks), followed by maintenance doses.

It is important to note that excessive vitamin D intake can be harmful, potentially leading to hypercalcaemia (elevated blood calcium levels), which may cause nausea, weakness, kidney problems, and cardiac arrhythmias. The safe upper limit for adults is generally considered to be 100 micrograms (4,000 IU) daily from supplements. Men should not exceed recommended doses without medical advice. Those with certain conditions, including granulomatous diseases (such as sarcoidosis) or hyperparathyroidism, should be particularly cautious with vitamin D supplementation. Vitamin D may also interact with certain medications, including thiazide diuretics and digoxin.

If you are taking medications or have existing health conditions, particularly kidney disease or conditions affecting calcium metabolism, consult your GP before starting vitamin D supplements. Report any suspected side effects from supplements via the MHRA Yellow Card Scheme (yellowcard.mhra.gov.uk).

Best Sources of Vitamin D for Men in the UK

Sunlight Exposure

In the UK, the primary natural source of vitamin D is sunlight exposure during spring and summer months (late March to September). When UVB rays strike the skin, they trigger vitamin D synthesis. For most men, short, regular periods of sun exposure on the forearms, hands, or lower legs during spring and summer can support vitamin D production. Men with darker skin may need longer exposure times due to higher melanin content, which reduces UVB penetration.

It is crucial to balance vitamin D synthesis with skin cancer prevention. The NHS advises that sun exposure should be brief and does not require sunbathing or tanning. You should be careful not to burn and should use sun protection if you're outside for longer periods. Between October and March, UVB radiation in the UK is insufficient for vitamin D synthesis, making dietary sources and supplementation essential.

Dietary Sources

Naturally occurring dietary vitamin D is relatively limited. The richest sources include:

• Oily fish: Salmon, mackerel, sardines, and herring provide substantial amounts (approximately 5–20 micrograms per 100g serving, varying by species)

• Egg yolks: Contain modest amounts (approximately 1–2 micrograms per egg)

• Red meat and liver: Provide small quantities

• Fortified foods: Many UK products are fortified with vitamin D, including breakfast cereals, fat spreads, and some plant-based milk alternatives

Supplementation

Given the challenges of obtaining adequate vitamin D from sunlight and diet alone in the UK, supplementation is a reliable method for maintaining sufficient levels, particularly during autumn and winter. Vitamin D supplements are available in two forms: vitamin D3 (cholecalciferol) and vitamin D2 (ergocalciferol). Vitamin D3 is generally considered more effective at raising and maintaining blood levels. Supplements are widely available from pharmacies and supermarkets at modest cost. Men should look for products containing 10 micrograms (400 IU) for daily maintenance.

If you have symptoms potentially related to deficiency—such as bone pain, muscle weakness, or frequent infections—contact your GP, who may arrange blood testing to assess your levels and recommend appropriate management. Routine testing is not required for well individuals following standard supplementation advice.

Frequently Asked Questions