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Vitamin D is an essential nutrient that supports bone health, muscle function, and the immune system. Vitamin D occurs naturally in certain foods, and can also be produced by our bodies with the help of the sun’s ultraviolet (UV) rays- which is why it is also called the sunshine vitamin. Vitamin D deficiency is one of the most common vitamin deficiencies, particularly in people who work indoors, live in cold or cloudy climates, have darker skin, or who wear clothes that cover most of their skin daily (Parva et al., 2018, Libon et al., 2013) . Sunlight exposure is one of the best sources of vitamin D- but how much vitamin D do we need? How much of our vitamin D requirement can we get from the sun? Read on to learn more.
How do our bodies produce vitamin D from sunlight?
Our bodies can create vitamin D with help from the sun. When the sun’s UVB rays hit the skin, a chemical in the skin called 7-dehydrocholesterol is converted into vitamin D3. It is then carried to the liver and kidneys to be converted into an active form of vitamin D that can be used by the body (Harvard Health, 2021). Vitamin D is unique because it is one of the only vitamins that the human body can synthesize itself with the help of the sun.
How much vitamin D do you need?
The amount of vitamin D you need per day depends on your age. For most people, a minimum intake of 10 micrograms per day is sufficient. For women and men aged 70 or older, a minimum intake of 20 micrograms per day is recommended (Voedingscentrum). Many people can get sufficient vitamin D from sunlight and their diet. If your vitamin D levels are low, your doctor may recommend taking supplements.
How long do you have to be in the sun to get enough vitamin D?
In the spring, summer, and autumn, it is advised to spend at least fifteen to thirty minutes in the sun between 11:00 and 15:00 with at least your head and hands uncovered (Voedingscentrum). The more skin that is exposed to the sun, the faster your body produces vitamin D, meaning less time in the sun is required.
During sunlight exposure, your body produces vitamin D and stores excess quantities in body fat. This stock can be used in the future when there is a lack of sunlight or other vitamin D sources. In countries that have low sunlight in the winter, it may be difficult to get enough vitamin D from sunlight alone. While your body can use its stock of stored vitamin D, it is important to try and maintain your levels during winter by eating vitamin D rich foods, getting sun exposure where possible, and using supplements if needed.
What are the signs of a vitamin D deficiency?
Most people with a vitamin D deficiency do not experience any noticeable symptoms, or may attribute their symptoms to something else. However, if you’re often exhausted or have bone and muscle pain it could be a sign of a vitamin D deficiency. Other symptoms of a (long-term) vitamin D deficiency are:
- Fatigue
- Hair loss
- Muscle weakness
- Depression
- Bone deformities
- More frequent illnesses
Source: Cleveland Clinic, 2022
Do you experience one or more of the mentioned symptoms? Testing your vitamin levels can be a good first step in uncovering the potential cause of your symptoms. This can easily be done with Homed-IQ’s Vitamin Deficiency Test. This blood test checks the level of vitamin B12, vitamin D, and vitamin B9 (folate) in your blood. The test is easy to take at home and is examined in a certified laboratory.
Can you get too much vitamin D from sun exposure?
No, it is not possible to get too much vitamin D from the sun. Vitamin D toxicity is usually caused by taking too many supplements, not from sun exposure or diet. However, too much sunbathing can increase your risk of skin cancer, and sunscreen and/or protective clothing are recommended during extended periods of sun exposure (NHS, 2020).
Does sunscreen affect vitamin D production?
Sunscreen protects your skin from sunburns by blocking UV light. In theory, this means that sunburn can also lower vitamin D production, as UV light is needed to produce vitamin D. In practice, the effect of sunscreen on vitamin D production has been found to be minimal, because there are few people who use enough sunscreen to block all the UV light from the skin, and many do not apply sunscreen daily. While sunscreen use can block vitamin D production, it is unlikely it will have a significant impact on your vitamin D levels (Harvard Health, 2020).
Does your body also produce vitamin D when it is cloudy?
The sun does not have to shine brightly for your body to produce vitamin D. Your body also produces vitamin D in cloudy weather, as UV light is present even if clouds are in the way. However, less intense sunlight means fewer UV rays and that vitamin D will be produced more slowly. As a result, it’s recommended to stay outdoors with your skin exposed longer on cloudy days in order to produce sufficient vitamin D.
What are other sources of vitamin D?
Some people do not get enough vitamin D from the sun- especially those who spend most of the day indoors. Fortunately, vitamin D can also be obtained from your diet. To boost your dietary vitamin D intake, be sure to incorporate the following foods into your diet:
- Egg yolks
- Herring
- Salmon
- Tuna
- Certain mushrooms
- Dairy
- Tofu
Source: Harvard Health, 2022
If you are unable to get enough vitamin D through food and sunlight exposure, supplements are also an effective way to maintain your vitamin D levels. Although vitamin D is necessary for health, excessive use of supplements can pose health risks. To ensure you are not getting too much vitamin D, always consult a doctor before starting supplements. For more information about vitamin D overdose, read our blog.
In short, sunlight is the most important natural source of vitamin D. The amount of vitamin D you need daily differs per person, but it is important to try and get some sun exposure daily when possible. By getting sunlight exposure when the weather allows it, you can build up your vitamin D stores for darker or cloudier months. In addition to sunlight, you can also obtain vitamin D from food or supplements. If you spend a lot of time indoors or are otherwise not exposed to the sun much, consider testing your vitamin D level. The insights from your test results can help you understand if you need to increase your exposure to sunlight, make changes to your diet, or speak to your doctor about using vitamin D supplements.
References:
Harvard Health. (2020, October 13). 6 things you should know about vitamin D. https://www.health.harvard.edu/staying-healthy/6-things-you-should-know-about-vitamin-d
Harvard Health. (2022, November 14). Vitamin D. The Nutrition Source. https://www.hsph.harvard.edu/nutritionsource/vitamin-d/
Libon, F., Cavalier, E., & Nikkels, A. (2013). Skin Color Is Relevant to Vitamin D Synthesis. Dermatology, 227(3), 250–254. https://doi.org/10.1159/000354750
Parva, N. R., Tadepalli, S., Singh, P., Qian, A., Joshi, R., Kandala, H., Nookala, V., & Cheriyath, P. (2018). Prevalence of Vitamin D Deficiency and Associated Risk Factors in the US Population (2011-2012). Cureus. https://doi.org/10.7759/cureus.2741
Voedingscentrum. (n.d.). Vitamine D. https://www.voedingscentrum.nl/encyclopedie/vitamine-d.aspx#:~:text=Voor%20iedereen%20geldt%20een%20aanbevolen,via%20de%20zon%20en%20voeding.
NHS. (2021, November 19). Vitamin D. nhs.uk. https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/#:~:text=You%20cannot%20overdose%20on%20vitamin,skin%20damage%20and%20skin%20cancer.
