What Is Vitamin D? Discover Its Surprising Benefits & Safe Sources

Vitamin D is one of the most important nutrients your body depends on, yet many people don’t fully understand what it is or why it matters.

Often called the "sunlight vitamin," vitamin D is essential for immunity, mood, bone health, and muscle strength. But getting enough isn't always as simple as stepping outside. Modern lifestyles, indoor work, climate, and even skincare habits have made natural light exposure unreliable for many.

As deficiency becomes more common, wellness professionals are rethinking how to support healthy levels. That includes turning to controlled light environments like professional tanning beds, which offer a consistent, science-backed way to help the body produce its own vitamin D.

What Is Vitamin D?

Vitamin D is a fat-soluble nutrient that acts more like a hormone than a traditional vitamin. Your body can make it on its own, but only when your skin is exposed to specific types of light, commonly referred to as the sunlight spectrum.

Unlike most essential nutrients, vitamin D isn’t primarily sourced through food. Instead, it’s synthesised in the skin when exposed to light. That process converts a compound in the skin (7-dehydrocholesterol) into vitamin D3, which is then activated by the liver and kidneys.

There are two main forms of vitamin D:

• Vitamin D2 (ergocalciferol): comes from plant sources and is also found in fortified foods.
• Vitamin D3 (cholecalciferol): is made in your skin and found in some animal-based products like oily fish and egg yolks.

D3 is more biologically active and easier for your body to absorb. This is why it's considered the most effective form, especially when produced naturally.

While vitamin D is commonly associated with sunlight, it's better understood as a biological response to light. It plays a behind-the-scenes role in many of your body's vital systems, from bone development to immune regulation.

6 Health Benefits of Vitamin D

Because of its structure, vitamin D helps other hormones to do their jobs. For example, it helps the body to absorb calcium, magnesium, and iron better. But its real role comes when our body converts it into vitamin D3, leading to various health benefits. Below are the most clinically recognized benefits of maintaining healthy vitamin D levels, supported by published research.

1. Boost Immune System

Vitamin D enhances the immune system’s ability to defend against infections. It supports the production and activation of T-cells and other white blood cells that identify and fight pathogens. A randomized controlled trial in Japanese schoolchildren found that vitamin D supplementation significantly reduced the incidence of influenza A infections (Urashima et al., 2010).

Additionally, a study by Agmon-Levin et al. (2013) suggests that vitamin D helps control inflammation. It may also lower the chance of diseases like multiple sclerosis and rheumatoid arthritis

2. Helps Treat Depression

Vitamin D does more than help when you are sick. It also helps control mood and may lower the risk of depression. Some researchers found that people with depression felt better after getting more vitamin D (Anglin et al., 2013).

Another study found that people with fibromyalgia who had low vitamin D were more likely to have anxiety and depression (Makrani et al., 2017).

Seasonal Affective Disorder (SAD) is another condition closely tied to vitamin D, often affecting people during the winter months when there is less sunlight. That’s because shorter days and cloudy skies reduce your skin’s ability to produce vitamin D naturally, which may worsen low mood during the colder months (Melrose, 2015).

3. Helps with Weight Loss

Raising your vitamin D levels may support healthy weight loss. Research shows that vitamin D, especially when combined with calcium, can help reduce body fat in certain groups. For example, a study by Major et al. (2009) found that overweight women with low calcium intake who took both vitamin D and calcium supplements lost more body fat than those who did not.

Vitamin D may play a role in weight management by helping to regulate appetite. Some scientists believe that vitamin D affects the hormones that control hunger and fullness, such as leptin and ghrelin. These hormones, in turn, signal to the brain about when to eat and when to stop (Pereira-Santos et al., 2015).

In addition, low vitamin D levels have been linked to a higher risk of obesity and difficulty losing weight (Vimaleswaran et al., 2013). People who spend more time in sunlight, which helps the body make vitamin D, may find it easier to manage their weight.

4. Supports Healthy Bones

Vitamin D helps your body absorb calcium and phosphorus, two minerals your bones need to stay strong. Without enough vitamin D, your body can’t use these minerals properly, even if your diet contains plenty.

Bones are always breaking down and rebuilding. Vitamin D helps bones repair and stay dense. If your vitamin D levels remain too low, your bones may become soft, weak, or more likely to break. In adults, this can lead to conditions like osteomalacia or osteoporosis (National Institutes of Health, 2022). Older adults, individuals with darker skin, and those who receive limited sunlight are particularly at risk for vitamin D deficiency (Mayo Clinic, 2024).

The recommended daily amount of vitamin D for most adults is 600–800 IU. You can get vitamin D from safe sun exposure, fatty fish, fortified foods, supplements, or tanning beds.

5. Reduce the Risk of Diabetes

Most people connect type 2 diabetes with poor diet and lack of exercise, but low vitamin D may also play a role. Several studies have found that people with low levels of vitamin D in their blood are more likely to develop type 2 diabetes over time (Song et al., 2013; Forouhi et al., 2008).

Vitamin D is thought to help control inflammation in the body and support the function of insulin-producing cells in the pancreas. Without enough vitamin D, inflammation can rise and disrupt how your body produces and uses insulin. This makes it harder to keep your blood sugar stable and may increase the risk of insulin resistance (Pittas et al., 2019).

6. Decreases Cardiovascular Disease

Vitamin D may also help protect your heart. Studies have found that people with low vitamin D levels are more likely to develop heart disease, high blood pressure, and even heart failure (Dobnig et al., 2008; Kunutsor et al., 2013).

One reason for this is that vitamin D helps control an enzyme called renin, which affects how much blood flows through your arteries and veins. When vitamin D levels are low, renin can become unbalanced, which may raise your blood pressure and put extra strain on your heart. A balance in vitamin D levels may also help lower inflammation, another risk factor for heart disease (Li et al., 2004; Calton et al., 2015).

Why Vitamin D Deficiency Is on the Rise

More and more people around the world are experiencing low vitamin D levels. But why is that happening, even in sunny countries? The answer has to do with how modern life affects our exposure to natural light (Holick, 2007).

We Spend More Time Indoors

One of the biggest reasons for vitamin D deficiency is our lifestyle. Most people work or study indoors during the day, limiting their exposure to sunlight. Even short commutes, digital jobs, or screen-based entertainment can keep us inside for long hours (Palacios & Gonzalez, 2014).

Geography and Weather

If you live in a northern country, a cloudy region, or experience long winters, your body may not get enough sunlight throughout the year. During the colder months, the sun’s rays are often too weak to trigger vitamin D production, especially through windows (Holick, 2007).

Aging and Skin Tone

As people age, their skin becomes less efficient at making vitamin D. In addition, individuals with darker skin tones have more melanin, which naturally blocks UV light. This means they may need more time in the sun to produce the same amount of vitamin D as someone with lighter skin (Clemens et al., 1982).

Diet Alone Isn’t Enough

Very few foods naturally contain vitamin D. Fatty fish, such as salmon, egg yolks, and fortified milk or cereals, can help, but even a healthy diet may not provide enough. That’s why light exposure is so important (NIH, 2022).

4 Ways to Get Enough Vitamin D—Naturally and Safely

Your body needs vitamin D every day, but how do you get enough, especially when sunlight is limited or your lifestyle keeps you indoors? Here are four safe and effective ways to keep your levels in a healthy range.

1. Spend Time in the Sun (When You Can)

Sunlight is the most natural source of vitamin D. When UV light hits your skin, your body starts making it on its own. Just 10–30 minutes of midday sun exposure a few times a week can be enough for many people, depending on your location, skin tone, and season (Webb et al., 2010).

But too much sun can damage your skin. If you’ll be outside for longer periods, always use sun protection after your initial exposure. And remember, cloudy weather and winter months make sunlight less effective, even if you’re outdoors (Holick, 2007).

2. Use Tanning Beds—Professionally and with Care

Tanning beds that use specific types of UV light can help stimulate vitamin D production, especially during darker seasons. In controlled settings like wellness clinics, beauty centres, or tanning salons, UV light may support your body’s ability to make vitamin D without depending solely on sunshine (Kimball et al., 2017). Always follow professional guidance when using tanning beds for health purposes.

3. Add Vitamin D-Rich Foods to Your Diet

Although diet alone isn’t usually enough to meet your daily needs, it still helps. Look for foods like oily fish (salmon, sardines, mackerel), fortified milk or plant-based drinks, egg yolks, and mushrooms exposed to sunlight (NIH, 2022; Medical News Today, 2023).

4. Consider Supplements if Recommended

If you’re not getting enough vitamin D from sunlight or food, a supplement may be useful. Your doctor can test your blood levels and recommend the right dose if you’re low or at risk of deficiency. Vitamin D3 is often preferred because it’s easier for the body to absorb (NIH, 2022).

Supplements can be especially helpful during winter months, or for people with medical conditions that limit how well their body makes or uses vitamin D.

Comparison: Sunlight vs Food vs Supplements vs Tanning Beds

Top Vitamin D Myths, Busted

There’s a lot of confusion about vitamin D. Let’s set the record straight by busting some of the most common myths.

Myth 1: You Only Need Vitamin D for Your Bones

The truth: While vitamin D does support bone health, that’s only part of the picture. It also helps regulate your immune system, supports brain function, and may reduce your risk of heart disease, diabetes, and depression (Holick, 2007; Pilz et al., 2013).

Myth 2: You Can Get Enough from Food Alone

The truth: It’s hard to get enough vitamin D from food. Even with a healthy diet, you might only get a small part of what your body needs. Most people need extra help from sunlight, light therapy, or supplements, especially in winter (Vitamin D Deficiency: Symptoms, Causes, and Health Risks, n.d.)

Myth 3: If You Go Outside, You’re Getting Enough Vitamin D

The truth: Just being outside isn’t always enough. Cloudy weather, clothing, sunscreen, or glass windows can block the UV light your skin needs. Plus, most of us don’t spend enough time outdoors during peak daylight hours (Barrie, 2025)

Myth 4: Tanning Beds Are Only for Cosmetic Use

The truth: Modern tanning beds used in wellness and clinical settings can help stimulate vitamin D production, especially when natural sunlight is limited. When used responsibly under professional guidance, they offer a controlled way to support your vitamin D levels (Kimball et al., 2017)

Myth 5: You Can’t Get Too Much Vitamin D

The truth: You can—but it’s rare, and it usually comes from overusing supplements. Your body stops making vitamin D from sunlight once you’ve had enough. That’s why getting vitamin D through safe sun or light-based exposure is more balanced (Vitamin D Toxicity (Hypervitaminosis D), 2025; Rdn, 2024).

Vitamin D: A Simple Key to Better Health 

Vitamin D is more than just a vitamin. It’s a key part of your body’s health. From stronger bones to a better mood, immune support, and heart health, keeping your levels in check can improve your well-being in many ways. 

But today’s indoor lifestyle, cloudy weather, and limited diet options make it harder to get enough. That’s why smart choices—like safe sunlight, light-rich foods, or controlled tanning bed use—can help. 

Whether you’re running a wellness centre, clinic, or fitness space, understanding the power of the “sunshine vitamin” opens the door to better care and better results for your clients. Want to learn how a tanning bed can support vitamin D production in your business? Talk to a specialist today.

Key Takeaways

• Vitamin D is essential for strong bones, immune health, mood balance, and heart function.
• Many people are deficient, especially in winter or if they spend most of their time indoors.
• You can get vitamin D from sunlight, certain foods, supplements, and controlled tanning bed use.
• Tanning beds, when used in professional settings, can safely support vitamin D production, especially when sunlight is limited.
• Getting enough vitamin D can help reduce the risk of serious health issues like depression, diabetes, and heart disease.
  
  

FAQs About Vitamin D

Can vitamin D really improve my mood and energy levels?

Yes. Low vitamin D can make you feel tired or sad. Getting enough vitamin D may help you feel happier and have more energy.

How can I quickly raise my vitamin D levels naturally?

Spending time in sunlight is one of the fastest ways. You can also use a professional tanning bed, eat vitamin D-rich foods like oily fish or fortified milk, and take a supplement if needed.

Are tanning beds a safe and effective source of vitamin D?

In professional settings like wellness centres and clinics, tanning beds can be a safe and reliable way to support vitamin D production, especially in winter or low-sunlight regions. Always use them under expert guidance.

What are the signs my vitamin D levels are too low?

You might feel tired, sad, have sore muscles, or get sick more often. Only a blood test can tell for sure if you are low in vitamin D.

How does skin type affect vitamin D absorption?

People with darker skin tones have more melanin, which can slow down vitamin D production. This means they may need more sun or longer exposure to produce the same amount as someone with lighter skin.

Can getting more vitamin D improve your sleep quality?

Yes. Vitamin D plays a role in regulating your sleep-wake cycle. Low levels have been linked to poor sleep or trouble falling asleep. Getting enough may help support more restful sleep.

Is it true that vitamin D helps boost immunity?

Absolutely. Vitamin D helps activate immune cells and defend the body against infections. It supports both short-term immune responses and long-term immune strength.

References

Agmon-Levin, N., Theodor, E., Segal, R. M., & Shoenfeld, Y. (2013). Vitamin D in systemic and organ-specific autoimmune diseases. Clinical Reviews in Allergy & Immunology, 45(2), 256–266. https://doi.org/10.1007/s12016-012-8342-y 

Anglin, R. E., Samaan, Z., Walter, S. D., & McDonald, S. D. (2013). Vitamin D deficiency and depression in adults: Systematic review and meta-analysis. The British Journal of Psychiatry: The Journal of Mental Science, 202, 100–107. https://doi.org/10.1192/bjp.bp.111.106666 

Barrie, L. (2025, March 18). 11 Vitamin D myths and facts. EverydayHealth.com. https://www.everydayhealth.com/vitamin-d/vitamin-d-myths-and-facts/ 

Calton, E. K., Keane, K. N., Newsholme, P., & Soares, M. J. (2015). The impact of vitamin D levels on inflammatory status: A systematic review of immune cell studies. PLOS ONE, 10(11), e0141770. https://doi.org/10.1371/journal.pone.0141770 

Clemens, T., Henderson, S., Adams, J., & Holick, M. (1982). Increased skin pigment reduces the capacity of skin to synthesise vitamin D3. The Lancet, 319(8263), 74–76. https://doi.org/10.1016/s0140-6736(82)90214-8   

Dobnig, H., Pilz, S., Scharnagl, H., et al. (2008). Independent association of low serum 25-hydroxyvitamin D and 1,25-dihydroxyvitamin D levels with all-cause and cardiovascular mortality. Archives of Internal Medicine, 168(12), 1340–1349. https://doi.org/10.1001/archinte.168.12.1340 

Healthline. Rdn, A. B. M. (2024, November 21). How much vitamin D is too much? The surprising truth. https://www.healthline.com/nutrition/how-much-vitamin-d-is-too-much 

Holick, M. F. (2007). Vitamin D deficiency. The New England Journal of Medicine, 357(3), 266–281. https://doi.org/10.1056/nejmra070553 

Kimball, S. M., Lee, J., & Vieth, R. (2017). Sunbeds with UVB radiation can produce physiological levels of serum 25-Hydroxyvitamin D in healthy volunteers. Dermato-Endocrinology, 9(1), e1375635. https://doi.org/10.1080/19381980.2017.1375635 

Kunutsor, S. K., Apekey, T. A., & Steur, M. (2013). Vitamin D and risk of future hypertension: Meta-analysis of 283,537 participants. European Journal of Epidemiology, 28(3), 205–221. https://doi.org/10.1007/s10654-013-9790-2 

Li, Y. C., Qiao, G., Uskokovic, M., Xiang, W., Zheng, W., & Kong, J. (2004). Vitamin D: A negative endocrine regulator of the renin–angiotensin system and blood pressure. The Journal of Steroid Biochemistry and Molecular Biology, 89–90, 387–392. https://doi.org/10.1016/j.jsbmb.2004.03.004 

Major, G. C., Alarie, F., Doré, J., Phouttama, S., & Tremblay, A. (2007). Supplementation with calcium + vitamin D enhances the beneficial effect of weight loss on plasma lipid and lipoprotein concentrations. The American Journal of Clinical Nutrition, 85(1), 54–59. https://doi.org/10.1093/ajcn/85.1.54 

Makrani, A. H., Afshari, M., Ghajar, M., Forooghi, Z., & Moosazadeh, M. (2017). Vitamin D and fibromyalgia: A meta-analysis. The Korean Journal of Pain, 30(4), 250–257. https://doi.org/10.3344/kjp.2017.30.4.250 

Mayo Clinic. (2024). Vitamin D deficiency. https://www.mayoclinic.org/healthy-lifestyle/nutrition-and-healthy-eating/expert-answers/vitamin-d-deficiency/faq-20058397 

Medical News Today. LD, M. W. R. (2024, February 5). What is vitamin D and why does the body need it? https://www.medicalnewstoday.com/articles/161618#summary 

Melrose, S. (2015). Seasonal Affective Disorder: An overview of assessment and treatment approaches. Depression Research and Treatment, 2015, 178564. https://doi.org/10.1155/2015/178564 

National Institutes of Health. (2022). Vitamin D: Fact sheet for consumers. https://ods.od.nih.gov/factsheets/VitaminD-Consumer/ 

Palacios, C., & Gonzalez, L. (2013). Is vitamin D deficiency a major global public health problem? The Journal of Steroid Biochemistry and Molecular Biology, 144, 138–145. https://doi.org/10.1016/j.jsbmb.2013.11.003 

Pereira-Santos, M., Costa, P. R. F., Assis, A. M. O., Santos, C. A. S. T., & Santos, D. B. (2015). Obesity and vitamin D deficiency: A systematic review and meta-analysis. Obesity Reviews, 16(4), 341–349. https://doi.org/10.1111/obr.12239 

Pilz, S., März, W., Cashman, K. D., Kiely, M. E., Whiting, S. J., Holick, M. F., Grant, W. B., Pludowski, P., Hiligsmann, M., Trummer, C., Schwetz, V., Lerchbaum, E., Pandis, M., Tomaschitz, A., Grübler, M. R., Gaksch, M., Verheyen, N., Hollis, B. W., Rejnmark, L., Karras, S. N., … Zittermann, A. (2018). Rationale and plan for vitamin D food fortification: A review and guidance paper. Frontiers in Endocrinology, 9, 373. https://doi.org/10.3389/fendo.2018.00373 

Pittas, A. G., Dawson-Hughes, B., Sheehan, P., Ware, J. H., Knowler, W. C., Aroda, V. R., … D2d Research Group. (2019). Vitamin D supplementation and prevention of type 2 diabetes. The New England Journal of Medicine, 381(6), 520–530. https://doi.org/10.1056/NEJMoa1900906 

Song, Y., Wang, L., Pittas, A. G., Del Gobbo, L. C., Zhang, C., Manson, J. E., & Hu, F. B. (2013). Blood 25-hydroxy vitamin D levels and incident type 2 diabetes: A meta-analysis of prospective studies. Diabetes Care, 36(5), 1422–1428. https://doi.org/10.2337/dc12-0962 

Urashima, M., Segawa, T., Okazaki, M., Kurihara, M., Wada, Y., & Ida, H. (2010). Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. The American Journal of Clinical Nutrition, 91(5), 1255–1260. https://doi.org/10.3945/ajcn.2009.29094 

Vitamin D deficiency: Symptoms, causes, and health risks. (n.d.). WebMD. https://www.webmd.com/diet/vitamin-d-deficiency 

Vitamin D toxicity (Hypervitaminosis D). (2025, June 2). Cleveland Clinic. https://my.clevelandclinic.org/health/diseases/24750-vitamin-d-toxicity-hypervitaminosis-d 

Vimaleswaran, K. S., Berry, D. J., Lu, C., Tikkanen, E., Pilz, S., Hiraki, L. T., … Hyppönen, E. (2013). Causal relationship between obesity and vitamin D status: Bi-directional Mendelian randomization analysis of multiple cohorts. PLOS Medicine, 10(2), e1001383. https://doi.org/10.1371/journal.pmed.1001383 

Webb, A. R., Kift, R., Durkin, M. T., O'Brien, S. J., Vail, A., Berry, J. L., & Rhodes, L. E. (2010). The role of sunlight exposure in determining the vitamin D status of the U.K. white adult population. The British Journal of Dermatology, 163(5), 1050–1055. https://doi.org/10.1111/j.1365-2133.2010.09975.x