The One Thing Dermatologists Say Is Essential for Healthy Skin

If you want to prevent damage to your skin and keep it healthy, dermatologists say the one thing you should do every day is ensure that you are protecting yorself from the sun.

Steven Daveluy, a board-certified dermatologist with the Wayne State University School of Medicine, told Newsweek sunscreen is the "most important thing" when it comes to preventing skin damage.

Is it OK to not use sunscreen?

Sun exposure, specifically exposure to ultraviolet B (UVB) rays, kickstarts a process in the body that produces vitamin D—a vital nutrient important for bone health and the immune system, among other functions.

But Daveluy said sun exposure is not a safe way to build up levels of vitamin D in the body due to the risk of developing skin cancer.

Given that the UVB rays from the sun (or indoor tanning booths) are the same ones that can cause sunburn and skin cancer, it is a "bad idea" to try to get your vitamin D from the sun, Daveluy said.

"Due to the skin cancer risk, the American Academy of Dermatology, the experts in skin, recommend against natural or artificial sun exposure to get vitamin D. It's important to protect your skin from the harmful ultraviolet rays of the sun," he said.

Ideally, your skin tone should stay roughly the same color all year round, so you you should try to avoid getting tanned or burnt, Daveluy said.

Dermatologists say there are several ways you can protect yourself from the sun's rays, including using sunscreen on exposed areas, wearing hats and clothing, and seeking shade where possible.

If you don't protect your skin, you increase the risk of developing skin cancer, skin discoloration, hyperpigmentation, freckles, wrinkles, and leathery skin. "[Sunscreen] will help prevent skin problems, including skin cancer, and skin aging," Daveluy said. "If you want beautiful skin for your whole life, sunscreen is your friend."

When it comes to the use of sunscreen, Daveluy recommends using it on any exposed areas any time you are outside in sunlight. "That includes winter and summer," he said. "You should put it on any areas that aren't covered by your clothes."

American Academy of Dermatology (AAD) board-certified dermatologist Chris Adigun also said people should use sunscreen every day if they want to avoid skin damage when being exposed to the sun.

"During the winter months, UVB rays (a small fraction of the rays that reach the earth's surface) are lessened, but UVA rays are not," Adigun said. "UVA rays cause more damage (mutagenic and UV-induced skin damage) than UVB rays. I advise patients to put their sunscreen right next to their toothpaste. Brush your teeth, put on sunscreen."

"We do not brush our teeth intermittently and expect excellent gum health. We should not wear sunscreen intermittently while exposing our skin to ambient light and expect our skin to not suffer from UV damage."

The time of day that you expose your skin to the sun makes a difference to how dangerous it is. In the early morning or late afternoon, the rays of the sun are more indirect, so less dangerous for the skin. But this also means that they are less effective at producing vitamin D.

The latitude you live at is also a factor in how much UV radiation you receive. In areas that are close to the equator, there is enough sunlight throughout the year to provide people with enough vitamin D, even though it is not a recommended source.

"But if you live here in Detroit, or similar latitudes, there isn't enough sunlight during the fall and winter, making it impossible to get your vitamin D from the sun," Daveluy said.

"In fact, if you spent every hour of every day nude at the top of the Empire State Building, you would not get enough sun exposure to provide the vitamin D your body needs. So, you'll need to get vitamin D from your diet for at least those two seasons. Why not just get it from your diet year round and avoid the risk of skin cancer? Vitamin supplements and dietary sources of vitamin D are the safe way to get your vitamin D."

There are only a handful of foods containing vitamin D, such as fish, mushrooms and milk—both dairy and some plant-based versions—as well as other fortified products. So, supplementation may be necessary.

What SPF is best?

SPF stands for sun protection factor, and the number indicates how well the sunscreen in question protects against sunburn.

According to the AAD, you should use a sunscreen that has an SPF of at least 30, which blocks 97 percent of the UVB rays. Higher SPF numbers will be able to block more of these UVB rays. But no sunscreen will be able to completely block all this radiation.

SPF is not an indicator of how long the sunscreen will protect you. After putting on sunscreen for the firs time, it is important to reapply every two hours or so when outdoors, even when it is cloudy, if you want to protect your skin, according to the AAD. Sunscreen should also be reapplied after swimming or excessive sweating.

Dermatologists recommend applying a coat on exposed areas around half an hour before heading outside. It is also important to apply sufficient quantities for maximum protection and ensure that you are using a broad-spectrum sunscreen that specifically protect against both UVA and UVB rays.

Is sunscreen better than sunblock?

Sunscreen and sunblock products both serve to protect the skin from the sun's rays but they do so in slightly different ways.

Sunscreen penetrates the skin and contains chemical compounds that absorb UV radiation. Sunblock on the other hand lie on top of the skin and contain ingredients that physically block UV light.

According to London-based dermatologist Cristina Psomadakis, people should choose the product that is best-suited to their needs—one type is not necessarily better than the other.

But she told the website Hhealth.com people with sensitive skin or skin conditions may prefer to use sunblock because it tends to be better tolerated and has a lower chance of causing irritation. "Because physical sunscreens sit on the surface of the skin, they are well-tolerated by even the most sensitive skin types," she said.

Benefits of sun exposure?

Outside of the mainstream view in dermatology, there are some researchers who argue that exposure to the sun may have several health benefits aside from the production of vitamin D, and that simply taking vitamin D supplements as a replacement for sunlight will not lead to optimal overall health.

Richard Weller, a dermatologist at the University of Edinburgh, found in research conducted in 2010 that exposure to sunlight produced nitric oxide—a previously unknown biological mechanism.

Nitric oxide dilates blood vessels and lowers blood pressure. Having high blood pressure puts you at increased risk for heart disease and stroke—two of the leading causes of death in the world.

Other research published in 2016 that tracked the sun exposure habits of nearly 30,000 Swedish women over 20 years found that "avoidance of sun exposure is a risk factor for death of a similar magnitude as smoking."

These results are observational in nature so cannot prove a causal link between avoiding sun exposure and having a higher risk of death from all causes. But these findings chime with other research that has associated sun exposure with a reduced risk of certain cancers, as well as lower levels of inflammation and improvements in mood, among other benefits. Getting sunlight in the morning also helps to regulate the circadian rhythm, boosting sleep quality—a vital aspect of our health.

"Vitamin D supplementation is not always an adequate substitute for sun exposure," Frank de Gruijl, co-author of a 2018 paper on sun exposure from Leiden University Medical Center in the Netherlands, said in a statement. "Sun exposure produces more than just vitamin D in your skin. It also produces nitric oxide, dopamine, beta-endorphin, cis-urocanic acid and various immune-active substances with effects throughout the body.

"A surprising recent finding is that the cis-urocanic acid present in the blood generates glutamate in the brain which enhances learning in mice. In addition, your immune system adjusts to work properly when you are exposed to the sun, and research shows that this can reduce your risk of developing autoimmune diseases such as multiple sclerosis."

The study, which was published in the International Journal of Environmental Research and Public Health, found that UV exposure that doesn't result in burns is a "health benefit" and should be recommended "in moderation".

"As with all things in life, we must maintain a good balance, in this case between beneficial and adverse health effects from sunlight. Besides being impractical, completely avoiding sun exposure appears to be unhealthy in many ways," the paper said.

The authors pointed to research showing that while sunburns and intermittent sun exposure are linked to increased risk of melanoma—the most serious form of skin cancer—chronic sun exposure, such as that received by some outdoor workers, has been linked with lower incidences of the disease.

Some organizations now recommend that there should be a balance between getting sun exposure and protecting from its harmful effects.

For example, the position statement of the Cancer Council Australia, which has been endorsed by the the Australasian College of Dermatologists, among other medical societies, says: "Ultraviolet radiation from the sun has both beneficial and harmful effects on human health. A balance is required between excessive sun exposure which increases the risk of skin cancer and enough sun exposure to maintain adequate vitamin D levels.

"Research suggests that prolonged sun exposure does not cause vitamin D levels to continue to increase further but does increase the risk of skin cancer. Short periods (of a few minutes) of sun exposure may be more efficient at producing vitamin D than long periods."

The paper recommends that when the UV index is above 3, sun protection is recommended when outdoors for more than few minutes. When the UV index is below 3, such as during the early morning or late afternoon in summer, or during winter in some parts of the country, sun protection is "not recommended unless outdoors for extended periods."

It said the use of sunscreen should not generally increase the risk of vitamin D deficiency, event though these products block a significant amount of UVB radiation.

"When sunscreen is tested in laboratory conditions it is shown to limit the effectiveness of vitamin D production, however, population studies have shown that regular use of sunscreen has little effect on vitamin D levels," the paper said.