Last updated: May 25, 2020
Vitamin D is an essential vitamin responsible for numerous body functions, ranging from supporting bone health to regulating the immune system. Unlike other vitamins, vitamin D functions as a hormone, meaning that it serves as a messenger, controlling and coordinating activities throughout the body. (4)
Vitamin D can be obtained from some foods, but the body can also create its own. Often called the “sunshine vitamin”, vitamin D is synthesized by the body when invisible UVB rays from the sun are absorbed by the skin. (22) Vitamin D may also be obtained through supplementation if food intake and sun exposure do not provide enough.
Vitamin D benefits
Outlined below are some of the health benefits of vitamin D.
Promotes healthy bones
Vitamin D is essential for maintaining strong, healthy bones. Bone mass is determined by a number of factors, including genetics, physical activity, and nutrition. By age 40, bone mass begins to decline, increasing our risk of fractures and osteoporosis, a condition characterized by low bone mass. (16)
Calcium, a mineral that helps build and maintain strong bones, requires vitamin D for proper absorption. Vitamin D helps the body absorb calcium and maintain adequate calcium in the blood, which promotes bone mineralization. (31) If vitamin D levels are not sufficient, calcium is released from the bones to help maintain blood calcium levels, contributing to soft, brittle bones. (16)
Research suggests that supplementing with vitamin D may increase bone density, resulting in a decreased risk of osteoporosis and fracture. (10)
Boosts immune health
The immune system, the body system responsible for defending the body from foreign invaders, is influenced by vitamin D status. Low levels of vitamin D are associated with increased susceptibility to infection. (1)
Research has also identified a link between poor vitamin D status and multiple autoimmune diseases, including lupus, multiple sclerosis (MS), and rheumatoid arthritis (RA). Deficiency is common in individuals with autoimmune disease, however, improving vitamin D status, though supplementation, diet, and sun exposure, may have protective effects against autoimmune disease. (17)(36)
Vitamin D supports the immune system by stimulating immune cells, such as macrophages and T-cells, that defend the body against harmful pathogens. (6)(17)
Several studies have found a correlation between optimal vitamin D levels and a decreased risk of upper respiratory tract infections, such as the common cold. (19)(28) It’s believed that this protective effect is the result of an increased expression of anti-microbial peptides in the lungs. (37)
May support healthy cardiovascular health
Vitamin D deficiency is a known risk factor for cardiovascular disease. While existing research is inconclusive, there is some evidence to suggest that supplementing with vitamin D may support heart health by lowering the risk of cardiovascular disease. (14)
Supplementing with vitamin D and calcium together may decrease risk of heart failure by 25 to 37%. (7)(8) Furthermore, sufficient vitamin D status may reduce elevated levels of parathyroid hormone (PTH), a hormone that regulates calcium in the blood. When excess PTH is secreted, risk of hypertension and heart failure increases. (3)(18)(38)
One study found that vitamin D supplementation may improve blood flow. (12) Another study of overweight adults with vitamin D deficiency investigated the effects of vitamin D supplementation on high blood pressure. After six months of supplementation, blood pressure significantly improved. (11)
May delay age-related cognitive decline
Age-related cognitive decline may be associated with vitamin D deficiency. Vitamin D receptors are found throughout the brain and research has shown that vitamin D may have neuroprotective effects, including reducing beta-amyloid plaques, a protein buildup that contributes to the development of Alzheimer’s disease. (30)
Vitamin D also acts as an antioxidant. Adequate levels of vitamin D may help reduce or prevent oxidative damage to nervous tissue that can lead to cognitive decline. (29)(35)
Some research suggests that supplementing with high doses of vitamin D may improve visual memory, particularly among individuals with vitamin D insufficiency. (25) While human studies are limited, one animal study showed that vitamin D supplementation improved age-related cognitive decline. (2)
How much vitamin D do you need?
The Food and Nutrition Board (FNB) sets intake reference values for various nutrients, including vitamin D. The established recommended dietary allowance (RDA) represents a daily intake of vitamin D that is sufficient to maintain bone health and normal calcium metabolism in healthy people.
Also established is the tolerable upper intake level (UL), which represents the maximum daily amount of a nutrient that is unlikely to cause adverse effects. Since vitamin D is stored in fat cells, excess amounts can build up to dangerous levels, causing high blood calcium and damage to the heart, blood vessels, and kidneys. (24)
The table below outlines the recommended daily intake for vitamin D in International units (IU) and micrograms (mcg), as well as the tolerable upper intake level, for different age groups. (24)
Recommended dietary allowances (RDAs) and tolerable upper intake level (UL) for vitamin D
Vitamin D deficiency
Vitamin D deficiency is very common, affecting approximately 41% of the population. (9) Low levels of vitamin D can have serious consequences and are associated with several health concerns, including diabetes, cancer, osteoporosis, and high blood pressure. (33)
Certain populations are at increased risk of developing a vitamin D deficiency, including older adults, those who live in northern regions of the world, breastfed infants (often a result of low vitamin D status in the mother), individuals with darker skin, people with a BMI ≥30, and individuals with certain chronic conditions affecting fat absorption (e.g., celiac disease and ulcerative colitis). (9)(20)(24)(32)
Vitamin D deficiency symptoms
Vitamin D deficiency may manifest itself in any of the following ways:
- Bone pain
- Chronic fatigue
- Muscle pain
- Weakness (15)
Sources of vitamin D
There are three key sources of vitamin D – sunlight, dietary sources, and supplements. (22)
Sunlight
Sunlight is a reliable source of vitamin D. When the UVB rays from the sun (the same rays that cause sunburn) come into contact with our skin, cholesterol in skin cells reacts by converting these rays into vitamin D. The success of this reaction depends on the amount of skin exposed to sunlight, as well as the amount of melanin in the skin. Melanin is the pigment that determines the color of our skin, hair, and eyes. The more melanin your skin contains, the darker your skin, resulting in fewer amounts of UVB rays absorbed by the skin. (23)
How much sun exposure is enough?
Spending approximately five to 30 minutes outdoors, twice per week, between the hours of 10 a.m. and 3 p.m. typically provides enough UVB to meet vitamin D needs. The face, arms, legs, or back, without sunscreen, should be exposed to the sun during this time. It’s important to note that sun exposure can increase the risk of skin cancer, so only spend short periods of time in the sun without protection. (21)
Dietary sources
Vitamin D is naturally found in a limited number of foods, as well as in some vitamin D-fortified products. The list below outlines the most common food sources.
Natural food sources of vitamin D include:
- Beef liver
- Cheese
- Egg yolk
- Fatty fish (e.g., mackerel, salmon, and tuna)
- Some mushrooms (e.g., chanterelle, maitake, and UV-treated portabella) (13)(26)
Foods fortified with vitamin D often include:
- Breakfast cereals
- Dairy products (e.g., milk and yogurt)
- Non-dairy milk (e.g., soy and almond milk)
- Orange juice (24)
Did you know? Since vitamin D is a fat-soluble vitamin, pairing vitamin D-rich foods or supplements with high-fat foods, such as avocados or nuts, can significantly increase absorption. (5)
Supplements
People who spend limited time in the sun, don’t consume enough vitamin D-containing foods, or have low blood levels of vitamin D may benefit from a vitamin D supplement. (27) Vitamin D supplements are typically available in various forms, including capsules, chewable tablets, and drops. Talk to your healthcare practitioner, who can help determine if supplementation is right for you.
Did you know? Vitamin K, specifically K2, is often paired with vitamin D in supplements. Vitamin K2 promotes bone calcification and minimizes the accumulation of calcium in the blood vessels. (34)
The bottom line
Vitamin D deficiency is common, however, it’s feasible to get enough through adequate sun exposure and intake of vitamin D-rich foods. If you are at risk for a vitamin D deficiency, consult your integrative healthcare practitioner for testing and specific recommendations.
- Aranow, C. (2011). Vitamin D and the immune system. Journal of Investigative Medicine: The Official Publication of the American Federation for Clinical Research, 59(6), 881–886.
- Briones, T. L., & Darwish, H. (2012). Vitamin D mitigates age-related cognitive decline through the modulation of pro-inflammatory state and decrease in amyloid burden. Journal of Neuroinflammation, 9, 244.
- Brown, S. J., Ruppe, M. D., & Tabatabai, L. S. (2017). The parathyroid gland and heart disease. Methodist DeBakey Cardiovascular Journal, 13(2), 49–54.
- Cesari, M., Incalzi, R. A., Zamboni, V., & Pahor, M. (2011). Vitamin D hormone: A multitude of actions potentially influencing the physical function decline in older persons. Geriatrics & Gerontology International, 11(2), 133–142.
- Dawson-Hughes, B., Harris, S.S., Lichtenstein, A.H., Dolnikowski, G., Palermo, N.J., & Rasmussen, H. (2015). Dietary fat increases vitamin D-3 absorption. Journal of the Academy of Nutrition and Dietetics, 115(2), 225‐230.
- Di Rosa, M., Malaguarnera, M., Nicoletti, F., & Malaguarnera, L. (2011). Vitamin D3: A helpful immuno-modulator. Immunology, 134(2), 123–139.
- Donneyong, M. M., Hornung, C. A., Taylor, K. C., Baumgartner, R. N., Myers, J. A., Eaton, C. B., Gorodeski, E. Z., Klein, L., Martin, L. W., Shikany, J. M., Song, Y., Li, W., & Manson, J. E. (2015). Risk of heart failure among postmenopausal women: A secondary analysis of the randomized trial of vitamin D plus calcium of the women’s health initiative. Circulation. Heart Failure, 8(1), 49–56.
- Ford, J.A., MacLennan, G.S., Avenell, A., Bolland, M., Grey, A., Witham, M., & RECORD Trial Group. (2014). Cardiovascular disease and vitamin D supplementation: Trial analysis, systematic review, and meta-analysis. American Journal of Clinical Nutrition, 100(3), 746‐755.
- Forrest, K. Y. Z., & Stuhldreher, W. L. (2011). Prevalence and correlates of vitamin D deficiency in US adults. Nutrition Research, 31(1), 48–54.
- Geddes, J. A., & Inderjeeth, C. A. (2013). Evidence for the treatment of osteoporosis with vitamin D in residential care and in the community dwelling elderly. BioMed Research International, 2013, 463589.
- Golzarand, M., Shab-Bidar, S., Koochakpoor, G., Speakman, J.R., & Djafarian, K. (2016). Effect of vitamin D3 supplementation on blood pressure in adults: An updated meta-analysis. Nutrition, Metabolism & Cardiovascular Diseases, 26(8), 663‐673.
- Harris, R. A., Pedersen-White, J., Guo, D. H., Stallmann-Jorgensen, I. S., Keeton, D., Huang, Y., Shah, Y., Zhu, H., & Dong, Y. (2011). Vitamin D3 supplementation for 16 weeks improves flow-mediated dilation in overweight African-American adults. American Journal of Hypertension, 24(5), 557–562.
- Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium. (2011). Dietary Reference Intakes for Calcium and Vitamin D. (A. C. Ross, C. L. Taylor, A. L. Yaktine, & H. B. Del Valle, Eds.). Retrieved from https://www.ncbi.nlm.nih.gov/books/NBK56070/
- Judd, S. E., & Tangpricha, V. (2009). Vitamin D deficiency and risk for cardiovascular disease. The American Journal of the Medical Sciences, 338(1), 40–44.
- Kennel, K. A., Drake, M. T., & Hurley, D. L. (2010). Vitamin D deficiency in adults: When to test and how to treat. Mayo Clinic Proceedings, 85(8), 752–758.
- Laird, E., Ward, M., McSorley, E., Strain, J. J., & Wallace, J. (2010). Vitamin D and bone health: Potential mechanisms. Nutrients, 2(7), 693–724.
- Liu, W., Zhang, L., Xu, H. J., Li, Y., Hu, C. M., Yang, J. Y., & Sun, M. Y. (2018). The anti-inflammatory effects of vitamin D in tumorigenesis. International Journal of Molecular Sciences, 19(9), 2736.
- Lotito, A., Teramoto, M., Cheung, M., Becker, K., & Sukumar, D. (2017). Serum parathyroid hormone responses to vitamin D supplementation in overweight/obese adults: A systematic review and meta-analysis of randomized clinical trials. Nutrients, 9(3), 241.
- Martineau, A.R., Jolliffe, D.A., Hooper, R.L., Greenberg, L., Aloia, J.F., Bergman, P., … Camargo, C.A.Jr. (2017). Vitamin D supplementation to prevent acute respiratory tract infections: Systematic review and meta-analysis of individual participant data. BMJ, 356, i6583
- Meehan, M., & Penckofer, S. (2014). The role of vitamin D in the aging adult. Journal of Aging and Gerontology, 2(2), 60–71.
- Moan, J., Dahlback, A., & Porojnicu, A. C. (2008). At what time should one go out in the sun? Advances in Experimental Medicine and Biology, 624, 86–88.
- Mostafa, W.Z., & Hegazy, R.A. (2015). Vitamin D and the skin: Focus on a complex relationship: A review. Journal of Advanced Research, 6(6), 793-804.
- Nair, R., & Maseeh, A. (2012). Vitamin D: The “sunshine” vitamin. Journal of Pharmacology & Pharmacotherapeutics, 3(2), 118–126.
- National Institutes of Health Office of Dietary Supplements. (2020). Vitamin D. Retrieved from https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
- Pettersen, J.A. (2017). Does high dose vitamin D supplementation enhance cognition?: A randomized trial in healthy adults. Experimental Gerontology, 90, 90‐97.
- Phillips, K. M., Ruggio, D. M., Horst, R. L., Minor, B., Simon, R. R., Feeney, M. J., … Haytowitz, D. B. (2011). Vitamin D and sterol composition of 10 types of mushrooms from retail suppliers in the United States. Journal of Agricultural and Food Chemistry, 59(14), 7841–7853.
- Pilz, S., Zittermann, A., Trummer, C., Theiler-Schwetz, V., Lerchbaum, E., Keppel, M. H., Grübler, M. R., März, W., & Pandis, M. (2019). Vitamin D testing and treatment: a narrative review of current evidence. Endocrine Connections, 8(2), R27–R43.
- Rondanelli, M., Miccono, A., Lamburghini, S., Avanzato, I., Riva, A., Allegrini, P., Faliva, M. A., Peroni, G., Nichetti, M., & Perna, S. (2018). Self-care for common colds: The pivotal role of vitamin D, vitamin C, zinc, and echinacea in three main immune interactive clusters (physical barriers, innate and adaptive immunity) involved during an episode of common colds: Practical advice on dosages and on the time to take these nutrients/botanicals in order to prevent or treat common colds. Evidence-Based Complementary and Alternative Medicine: eCAM, 2018, 5813095.
- Salim, S. (2017). Oxidative stress and the central nervous system. The Journal of Pharmacology and Experimental Therapeutics, 360(1), 201–205.
- Soni, M., Kos, K., Lang, I.A., Jones, K., Melzer, D., & Llewellyn, D.J. (2012). Vitamin D and cognitive function. Scandinavian Journal of Clinical and Laboratory Investigation, 243, 79‐82.
- Stein, S.H., & Tipton, D.A. (2011). Vitamin D and its impact on oral health: An update. The Journal of the Tennessee Dental Association, 91(2), 30‐35.
- The VitaminD Society. (n.d.). Vitamin D health benefits. Retrieved from https://www.vitamindsociety.org/benefits.php
- U.S. National Library of Medicine MedlinePlus. (2019). Vitamin D deficiency. Retrieved from https://medlineplus.gov/vitaminddeficiency.html
- van Ballegooijen, A. J., Pilz, S., Tomaschitz, A., Grübler, M. R., & Verheyen, N. (2017). The synergistic interplay between vitamins D and K for bone and cardiovascular health: A narrative review. International Journal of Endocrinology, 2017, 1–12.
- Wrzosek, M., Łukaszkiewicz, J., Wrzosek, M., Jakubczyk, A., Matsumoto, H., Piątkiewicz, P., … Nowicka, G. (2013). Vitamin D and the central nervous system. Pharmacological Reports, 65(2), 271‐278.
- Yang, C. Y., Leung, P. S., Adamopoulos, I. E., & Gershwin, M. E. (2013). The implication of vitamin D and autoimmunity: A comprehensive review. Clinical Reviews in Allergy & Immunology, 45(2), 217–226.
- Youssef, D. A., Miller, C. W., El-Abbassi, A. M., Cutchins, D. C., Cutchins, C., Grant, W. B., & Peiris, A. N. (2011). Antimicrobial implications of vitamin D. Dermato-endocrinology, 3(4), 220–229.
- Zittermann, A., Schleithoff, S.S., & Koerfer, R. (2006). Vitamin D insufficiency in congestive heart failure: Why and what to do about it?. Heart Failure Reviews, 11, 25.
Hi John,
Thank you for your feedback! As always, every individual case is unique, so we definitely recommend working with your healthcare provider for the best suitable action plan. It looks like you are on the right track with yours! Thank you for sharing your personal experience.
I agree with John’s input. Your dosing is outdated and many new research studies show benefits to higher serum levels. There is a direct inverse proportion to the amount of D to all cause mortality. With optimal levels 80-100, the risk of ALL disease decreases. Your article may scare people who have already been recommended by their provider to take higher doses of 5,000 – 10,000 IU and higher daily. Consider leaving out this part of the article to avoid contradiction of many providers suggestions.
Can you discuss IM Vitamin D?
What levels should someone start IM?
What is IM dosage and recomended frequency?
What is your opinion on taking Vitamin D supplements that also include Vitamin K? I’ve read that K helps with blood calcium levels that taking D might raise. Is this true?
Interesting.
Good article in general. The fortified foods with Vit D listed are generally laden with sugar and high in carbs.
Almond milk with 30’cal per cup is acceptable. Orange juice is liquid sugar as well. Label reading is essential. A yogurt with 2 grams of sugar per serving is acceptable. One cannot have the benefit of foods fortified with Vit D if they are already laden with Sugar.
How can you talk about vitamin D without vitamin K2? You guys should be on the cutting edge. What gives?
Hi Nancy, thank you for your comment! We always enjoy hearing from our community and have passed along your feedback to our content team. We appreciate you reaching out! Wishing you a healthy and enjoyable day ahead.
This is a good article, but it should be noted:
The best source for Vitamin D supplements should be Vitamin D3. One study published in the Journal of Endocrinology and Metabolism found that vitamin D3 was nearly twice as effective at increasing vitamin D levels in the blood compared to vitamin D2. For this reason, it’s generally recommended to select a vitamin D3 supplement whenever possible to optimize absorption.
D3 should also be paired with Vitamin K2. Vitamin D by itself displaces calcium. The K2 makes sure that calcium goes to your bones, not your arteries. D3 by itself also depletes magnesium, so its best to take magnesium in conjunction with Vitamin D3. Not necessarily at the same time of day but taken on the same day. Full-Fat, organic Coconut milk ( with no gums or extra fillers) is also a great healthy fat to take with vitamin D. 🙂
Cod liver oil is a potent form of vitamin D3 plus vitamin A and omega-3 fatty acids.
Can you take to much Vit D if you’re not deficient? If so whats the risk factor?
Thank you for the article. Can you tell me how I can determine my current vitamins d level?
Also what corresponding concentration I should take to reach optimum levels? Is there a rule of thumb?
Hi Lindsey, thank you so much for your question and feedback! We’ve included some information about vitamin K2 in the article. Here is a link to the corresponding research: (34)
Hi Ali, thank you so much for your feedback, we love hearing from our community! We’ve included some information about vitamin K2 in the article. Thanks again Ali, we really appreciate it!
Hi Jarrett, thank you so much for reaching out! We recommend checking in with your healthcare practitioner about testing your vitamin D levels. In the article, we’ve included a table of recommended dietary allowances (RDAs) and tolerable upper intake level (UL) for vitamin D. Your practitioner will be able to best support you with a supplement recommendation. Thanks again, Jarrett!
Hi Lewis, thank you very much for your comment, that’s a great question! You may find the How much vitamin D do you need? section of the article helpful. We also recommend talking with your healthcare practitioner about what they would recommend for your individual needs. Wishing you an enjoyable day ahead, Lewis!
I would like to hear more research about how vitamin D is absorbed based on skin pigment as well.
Hi Jessica, thank you for your comment! We have forwarded this to our Integrative Medical Advisory team to consider for future content pieces! We do have an article on skincare that we discuss briefly the benefits of vitamin D and includes some links to research. You can check it out here: https://fullscript.com/blog/healthy-skin-natural-supplements-and-vitamins
I see the RDA but what number or range should be our goal if we are looking at our lab work?
Hi Jennifer, thank you so much for reaching out! In this case, we recommend asking your healthcare provider about what they would recommend for you and your individual needs.
What is vitamin k2
Hi Michelle, thank you for your comment! This research reference explains more about vitamin K2.
Hi Dr. Thrower, thank you for your comment! Because we don’t offer IM vitamin D on our platform, we can only confidently address questions regarding supplemental forms. This study discusses the effects of IM and oral vitamin D.