How to Safely Get Vitamin D From Sunlight

Vitamin D, known as the “sunshine vitamin,” is essential for maintaining strong bones, a healthy immune system, and optimal nerve and muscle function. Despite its crucial role, an estimated 25% of the U.S. population—and nearly 1 billion people worldwide—have vitamin D deficiency.

One of the easiest ways to boost vitamin D levels is to spend time in the sun. When ultraviolet B (UVB) rays from the sun reach the skin, the body uses cholesterol in the skin to convert it to a useable form of vitamin D. The liver and kidneys then process this vitamin into its active form, calcitriol, which the body uses to support bone health, immune function, and other body processes.

While sunlight is a readily available and natural source of vitamin D for maintaining optimal levels, overexposure to sunlight poses health risks, such as sunburn and an increased risk of skin cancer.

This article discusses using the sun to meet your vitamin D needs safely. 

How Do You Get Vitamin D From the Sun?

Spending time in the sun allows your body to naturally produce vitamin D, making sunlight exposure a valuable tool for maintaining sufficient vitamin D levels and protecting your overall health. 

When UVB rays from sunlight reach your skin, they interact with a substance called 7-dehydrocholesterol, which is present in the outer layer of your skin (epidermis). The liver then converts 7-dehydrocholesterol into vitamin D3 (cholecalciferol), and the kidneys further process it into calcitriol—the active form of vitamin D your body needs.

The final form of vitamin D acts as a hormone, helping regulate calcium absorption, promote bone health, boost immunity, and support other essential body functions.

Tips for Getting Vitamin D From the Sun Safely

Sunlight is an excellent natural source of vitamin D, but overexposure to the sun poses health risks. Here are some tips to ensure you’re getting enough vitamin D without putting your skin at risk:

• Timing is key: Aim for 10 to 15 minutes of sun exposure during peak UVB ray hours, typically between 11 a.m. and 3 p.m. You may need 20 to 30 minutes of sunlight exposure on a cloudy day. 
• Sunscreen: Apply a broad-spectrum sunscreen with a sun protection factor (SPF) of 30 or higher to protect your skin from sunburns.
• Check the UV Index: Check your local UV index daily to determine the safest times for sun exposure. A UV index of 3 or higher is generally adequate for vitamin D synthesis. However, a higher UV index means a higher potential for UV damage, requiring additional protection from the sun. 
• Targeted exposure: The more skin you expose to sunlight, the more vitamin D your body makes, but only up to a point (between 10,000 to 15,000 international units). Staying out for extended periods or exposing more of your skin past a certain point increases the risk of sunburn. Wearing a T-shirt and shorts to expose your arms and legs should be sufficient to get enough vitamin D. 
• Consider supplements: If you have concerns about getting enough vitamin D from sunlight due to geographic location or health concerns, talk to a healthcare provider about vitamin D supplements or ways to get more vitamin D through your diet.

Why Skin Color May Affect Vitamin D Production

Your skin color influences how much vitamin D your body produces from sunlight exposure. Melanin, the pigment that determines your skin tone, absorbs ultraviolet radiation, including UVB rays responsible for vitamin D production. While this can help protect your skin from sun damage, it also reduces the UVB rays your body absorbs to promote vitamin D synthesis. 

People with darker skin tones may require longer sun exposure times to produce the same amount of vitamin D as those with lighter skin tones get. For example, a person with fair skin may require 15 minutes of sunlight, whereas a person with a darker skin tone may need 30 minutes for optimal vitamin D production.

What If You Live Far From the Equator?

Living far from the equator means residing farther north or south from the Earth’s equator—an invisible line that circles the Earth halfway between the North and South Poles. Latitude is the angular distance north or south of the equator; the higher the latitude, the farther away you live from the equator. The farther you are from the equator (higher latitude), the more slanted the sun’s rays hit your skin, making vitamin D production less efficient.

Living far from the equator can pose challenges for maintaining adequate vitamin D levels, especially in winter. The lower angle of the sun, coupled with shorter daylight hours, can significantly reduce UVB exposure and increase the risk of vitamin D deficiency. 

What Factors Prevent You From Getting Vitamin D From the Sun?

In addition to geographic location and skin tone, certain other factors can prevent you from getting vitamin D from the sun or hinder your body’s ability to convert UVB rays to vitamin D. These include: 

• Limited sun exposure: Spending minimal time outdoors, especially during peak hours when UVB rays are strongest (11 a.m. to 3 p.m.), reduces vitamin D production in the body. Wearing clothing that covers most of your skin can also limit UVB ray penetration.  
• Sunscreen use: While sunscreen is crucial for sun protection, broad-spectrum sunscreens with SPF 30 or higher block 97% of the sun’s UVB rays.
• Air pollution: Pollutants in the atmosphere can absorb and scatter UVB rays, limiting vitamin D synthesis. 
• Age: The body synthesizes and metabolizes vitamin D less efficiently as we age; older adults have higher rates of vitamin D deficiency than other age groups.
• Obesity: People with obesity are at an increased risk of vitamin D deficiency. Research suggests that excess body fat may dilute vitamin D and decrease vitamin D synthesis.
• Medical conditions: Because the kidneys and liver are essential for producing vitamin D, people with kidney and liver diseases are at an increased risk of deficiency.
• Medications: Certain medications, including anti-seizure medications, laxatives, diuretics, statins, calcium channel blockers, proton pump inhibitors, H2 antagonists, corticosteroids, antibiotics, antiviral medications, and certain chemotherapy drugs, can reduce vitamin D synthesis.

Other Ways to Get Vitamin D

Although sunlight is a natural and efficient way to boost your vitamin D levels, it’s not always accessible or a practical option. Other ways to boost your vitamin D levels include:

• Diet: Consuming foods rich in vitamin D, such as fatty fish (salmon, mackerel, and sardines), eggs, and mushrooms can help increase your vitamin D levels. Other foods are fortified with vitamin D, such as milk (including plant-based alternatives), yogurt, cereals, and orange juice. Check nutrition labels to determine the vitamin D content.
• Supplements: Taking vitamin D supplements is an easy way to increase your vitamin D intake. Vitamin D3 is the best option for supplementation. Discuss the appropriate dosage with a healthcare provider. 
• Phototherapy: Special UV lamps and bulbs designed to produce UVB radiation may be an alternative to natural sunlight, helping stimulate vitamin D production in the skin.
• Regular monitoring: Regularly checking your vitamin D levels through blood tests can help you determine when to adjust your intake to maintain optimal levels. 

Dangers of Too Much Sunlight

While protected sunlight exposure is good for you in moderation, excessive sun exposure comes with health risks, including:

• Skin changes: Excess UVB rays can cause sunburn—red, painful, sometimes blistering skin—along with other skin changes, including freckles and moles.
• Premature aging: Sun exposure causes increased skin laxity by damaging collagen and elastin proteins. Too much sun can lead to wrinkles, tight or leathery skin, and sun spots (dark spots).  
• Weakened immune system: Excessive UV exposure can weaken the immune system, increasing the risk of illness. 
• Heat-related illnesses: Prolonged exposure to direct sunlight and high temperatures can lead to heat exhaustion and heat stroke. Symptoms include dizziness, nausea, headache, rapid heartbeat, and confusion. Heat stroke is a medical emergency and requires immediate attention.
• Skin cancer: Over time, exposure to UV rays and repeated sunburns can damage the skin and increase the risk of skin cancer.
• Eye damage: UV rays can harm the eyes, including damaging the corneas (outer layer of the eyes) and increasing the risk of cataracts.

Summary 

Vitamin D is essential for bone strength, immune function, and overall health. Sunlight is a natural source of vitamin D, and enjoying just 10 to 15 minutes in the sun each day can help boost your body’s vitamin D levels. Factors like skin tone, geography, and sunscreen use can affect how much vitamin D your body produces from the sun.

Eating vitamin D-rich foods and vitamin D3 supplements may help increase your vitamin D levels when sunlight exposure is not an option. While sunlight is an excellent source of vitamin D, excess sun exposure comes with health risks like premature aging and an increased risk of skin cancer.