How Much Sun Exposure Do You Need for Optimal Vitamin D Status?

Vitamin D and sun exposure

Vitamin D is essential for health and well-being. This fat-soluble vitamin enhances calcium absorption, healthy muscle function, and helps preserve bone health and prevent osteoporosis. Plus, it plays a role in modulating your immune system and keeping inflammation in check. Important stuff, right?

Despite the role vitamin D plays in health, many people don’t get enough of the sunshine vitamin. Studies suggest that, depending on the study, between 18% and 40% of the population has a suboptimal vitamin D level.

Extreme vitamin D deficiency causes bone disease rickets in children. Kids with rickets have bones that are softer and weaker. The bone weakness of rickets leads to skeletal problems like bowlegs and knock knees. Severe vitamin D deficiency in adults can lead to osteomalacia, weak bones that break with little force.

The above problems occur with severe vitamin deficiency. Lesser degrees of a vitamin D shortfall can cause less severe symptoms. Some of these include muscle weakness, bone pain, and fatigue. Less severe vitamin D deficiency may be overlooked because it causes vague symptoms like fatigue or depression, and it takes a while for a low vitamin D level to lead to health problems. Unlike nutrients, you can eat a healthy diet and still be deficient in vitamin D. Many people are low in vitamin D and aren’t aware of it.

Where Do You Get Vitamin?

Vitamin D is a hormone your body can make with exposure to sunlight. Unlike most vitamins, food is not the best source of vitamin D. You can get modest quantities of vitamin D by eating fatty fish, beef liver, or egg yolks but diet alone often isn’t enough to maintain a healthy vitamin D level.

Dairy products like cheese and yogurt contain small quantities of vitamin D. Some packaged foods, like breakfast cereal and some dairy products, are fortified with vitamin D. Infant formula, fat and some non-dairy milk alternatives are other packaged foods that may contain vitamin D. Read the label to be sure. But it’s hard to consume enough vitamin D-rich foods to meet your body’s vitamin D requirements. That’s why sun exposure is so important.

How Sunlight Supplies Your Body with Vitamin D

What’s so magical about sun exposure and vitamin D? When UVB (ultraviolet light B rays) from sunlight touch your body, your skin synthesizes 7-dehydrocholesterol from cholesterol to produce vitamin D. This precursor to vitamin D is then activated by your liver and kidneys to produce a form of active vitamin D that has biological effects on your body. If all goes well, your body makes enough vitamin D for optimal health, but many people don’t get enough sun exposure for this to happen

How Much Sun Exposure Do You Need?

With most people spending their days indoors, it’s not surprising that so many people are deficient in vitamin D. question is how much sun exposure do you need?

There isn’t a one-size-fits-all answer to this question. People with darker skin need more sun exposure to maintain a healthy vitamin D level than those with lighter skin. Obesity and older age also increase the requirement for vitamin D and sunlight.

How much sun exposure is enough? The average person can make enough vitamin D from sun exposure by sitting out in the sun daily for around 15 minutes from March to September. During your sessions, don’t wear sunscreen as it blocks UVB rays that boost vitamin D synthesis. Depending upon where you live, however, UVB rays may not be strong enough to produce adequate vitamin D for health during the late fall and winter, from October to February.

Do You Need a Vitamin D Supplement?

What should you do if you live in an area that doesn’t get enough UVB rays in the late fall and winter? Take a vitamin D supplement. The best approach is to ask your healthcare provider to check your vitamin D level and determine where you fall on the vitamin D continuum. Based on that, they’ll tell you how much to take to optimize your level.

You may just need a vitamin D supplement during the winter months if you get enough outdoor exposure during the spring and summer. Unlike vitamin D supplements, you can’t overdose on vitamin D from sun exposure and it’s unlikely you could eat enough vitamin D containing foods to achieve a toxic vitamin D level.

If you can’t get your vitamin D level checked, don’t take more than 4,000 I.U. daily, as that’s the upper limit of what’s considered safe if you don’t know your level. It’s safest to take no more than 1,000 I.U. to 2,000 I.U. daily unless you’re low. Your body stores excess vitamin D, and too much can cause too much calcium to build up in your blood. It also places added strain on your kidneys and increases the risk of kidney stones. Plus, studies show the benefits of vitamin D follow a U-shaped curve. A low vitamin D level is harmful but having a high one can be too. However, most people are at greater risk of a level that’s too low rather than too high.

The Bottom Line

The amount of sun exposure you need to meet your vitamin D needs will vary with your age, whether you’re obese, and your skin color. However, most people can get enough during the spring and summer by sitting outside in the sun for 15 minutes daily. If you can’t, consider talking to your physician about taking a vitamin D supplement. Keep your vitamin D level in a healthy range, and you’ll enjoy better mental and physical health.


  • National Institutes of Health. “Vitamin D”
  • “Vitamin D – Health Professional Fact Sheet.” 26 Mar. 2021, ods.od.nih.gov/factsheets/vitamind-healthprofessional/.
  • Aranow, Cynthia. “Vitamin D and the immune system.” Journal of investigative medicine : the official publication of the American Federation for Clinical Research vol. 59,6 (2011): 881-6. doi:10.2310/JIM.0b013e31821b8755.
  • Wacker M, Holick MF. Sunlight and Vitamin D: A global perspective for health. Dermatoendocrinol. 2013 Jan 1;5(1):51-108. doi: 10.4161/derm.24494. PMID: 24494042; PMCID: PMC3897598.

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