Using sunscreen is crucial for skin health, especially during summer, but does it affect your vitamin D levels?
Vitamin D, essential for bone health, nerve function, and immune support, is primarily sourced from diet and sunlight. When skin is exposed to ultraviolet B (UVB) rays, it produces vitamin D naturally. According to Dr. Kellie Reed, a dermatologist at Westlake Dermatology in Texas, UVB rays interact with a protein called 7-dehydrocholesterol in the skin, converting it into vitamin D3, the active form of the vitamin.
However, the same UVB rays that aid in vitamin D production can also cause sunburn, a significant risk factor for skin cancer. This has led to widespread recommendations for sunscreen use to protect the skin.
Does Sunscreen Impact Vitamin D Absorption?
Despite its role in blocking UVB rays, sunscreen has minimal effect on vitamin D levels, according to Dr. Robert Den, a radiation oncologist and chief medical officer at Alpha Tau Medical. Research has consistently shown no direct link between sunscreen use and vitamin D deficiency. For instance, one study indicated that regular sunscreen users did not exhibit lower vitamin D levels compared to those who did not use sunscreen.
Dr. Reed explained that even though sunscreen blocks a significant portion of UVB rays, some still reach the skin. An SPF 30 sunscreen, for instance, blocks 97% of UVB rays, which is sufficient to allow some vitamin D production.
Moreover, people often apply sunscreen insufficiently. To be effective, an entire ounce should be used to cover exposed skin, with reapplication every two hours. However, most people apply it in smaller amounts, reducing its potential impact on vitamin D absorption.
Factors Affecting Vitamin D Synthesis from Sunlight
Several factors influence how much vitamin D you can produce from sunlight, including age, skin color, and exposure timing. Dr. Reed noted that individuals with darker skin produce less vitamin D from sunlight, as do older adults and those who cover most of their bodies. The body is most efficient at producing vitamin D when exposed to the sun around noon, when UVB rays are strongest. Environmental factors like clouds and air pollution can also affect vitamin D synthesis.
Although sunlight is a key source of vitamin D, most people can meet their needs through diet and supplements, said Dr. Den.
Safe Sun Exposure and Vitamin D
Despite concerns, skipping sunscreen to increase vitamin D intake is not advisable. Dr. Reed emphasized that there is no proven link between sunscreen use and vitamin D deficiency. Not using sunscreen exposes you to risks such as severe skin damage and cancer, which affects millions annually in the U.S.
For adults aged 19 to 70, the recommended daily intake of vitamin D is 600 IU or 15 mcg. However, about 22% of Americans have a moderate deficiency. A blood test can determine if you are at risk. Dr. Lauren Penzi from MDCS Dermatology suggests that 10 to 15 minutes of unprotected sun exposure a few times a week may suffice for maintaining adequate vitamin D levels without significantly increasing skin damage risk.
A study in the UK found that just 13 minutes of midday summer sunlight three times a week was enough to maintain healthy vitamin D levels for white adults. People with darker skin may require longer exposure.
In addition to sunlight, vitamin D can be obtained from supplements and fortified foods like dairy milk, plant-based milk, orange juice, and foods rich in vitamin D such as salmon, tuna, and mushrooms. Consulting a physician to check vitamin D levels and determine the best approach is recommended.
