WARNING!
This is an older article that may not reflect Dr. Mercola’s current view on this topic. Use our search engine to find Dr. Mercola’s latest position on any health topic.
By Dr. Mercola
Does wearing sunscreen prevent skin cancer? If you listen to public health officials that urge every man, woman and child to slather on sunscreen every day, you would think the answer is an unequivocal yes.
Aside from those who use sunscreen for the purpose of preventing wrinkles, it's a safe assumption that many people use it with the intent of preventing skin cancer. But here's the rub: wearing sunscreen may not actually protect you from cancer and, in some cases, may actually increase your risk.
Daily Sunscreen Use Versus Occasional Use: No Difference in Skin Cancer Rates
A Cochrane Review attempted to determine whether the use of topical sunscreen and physical sun-protective methods (such as wearing protective clothing, hats, and seeking shade) prevented the development of basal cell carcinoma (BCC) and cutaneous squamous cell carcinoma (cSCC) compared to taking no precautionary measures.1
There wasn't much data on the topic to be found, so the review includes the results of just one study, which compared the daily application of sunscreen with the occasional use of sunscreen over a period of 4.5 years.
Among the more than 1,600 Australian participants, there was no difference between the numbers of people who developed BCC or cSCC (the most common types of skin cancer) in the two groups during the trial period.
As noted in the Cochrane Review, "So, there did not seem to be a difference in applying sunscreen daily compared with using it occasionally."2
While I certainly don't recommend spending so much time in the sun that your skin gets burned, the one-size-fits-all recommendation from public health officials to apply sunscreen daily may be causing more harm than good.
The fact is, sunlight offers many benefits to your health, the majority of which are only beginning to be understood. Meanwhile, most sunscreens contain harmful chemicals and may not protect your skin from overexposure the way you think they do. Some may even increase your risk of cancer.
Certain Sunscreens May Speed the Development of Skin Cancer
Close to 16 percent of U.S. sunscreens contain vitamin A, which sounds like a natural addition that might be beneficial for your skin, acting as an antioxidant.
However, retinyl palmitate, a form of vitamin A, has been found to promote the development of skin tumors and lesions when applied topically and exposed to sunlight.3
The U.S. Food and Drug Administration's (FDA) National Center for Toxicological Research (NTP) has been studying the ability of vitamin A ingredients to trigger skin cancer when exposed to the sun for more than a decade.
One study on hairless mice revealed that the development of skin tumors was accelerated when a vitamin-A-laced cream was applied to the mice and then exposed to ultraviolet light daily for one year.4
Despite the known risks, these ingredients are still found in sunscreens with no warnings to consumers. The Environmental Working Group (EWG) reported:5
"Six years after EWG sounded the alarm about retinyl palmitate, the FDA still hasn't completed follow-up studies that will allow the agency to take a position on the safety of vitamin A and related chemicals in cosmetics and sunscreens.
Most cosmetics companies have not removed these ingredients from sunscreens and other skin and lip products … EWG calls for sunscreen makers to voluntarily stop adding this ingredient to sunscreens until there is proof that it can be safely used on sun-exposed skin. …
EWG recommends that consumers avoid sunscreens and other skin and lip products containing vitamin A, retinyl palmitate, retinol, retinyl acetate, retinyl linoleate and retinoic acid."
The SPF Myth: Is Higher SPF Really Better?
Dermatologists at Northwestern University in Chicago conducted a survey to assess people's understanding of sunscreen labels.6 Many people consider SPF (sun protection factor) as a leading factor in their decision of which sunscreen to buy, despite the fact that, in the study, fewer than half knew what SPF meant.
Meanwhile, most of the people surveyed believed that SPF 30 offered double the sun protection of SPF 15. It's an understandable assumption, but one that's blatantly false. In fact, the difference between the two is much smaller — about 4 percent.
While an SPF 15 sunscreen should filter out about 93 percent of UVB (ultraviolet B) rays, SPF 30 filters out about 97 percent. Higher SPFs offer only minute benefits beyond this, with SPF 50 blocking 98 percent, and SPF 100 blocking 99 percent, of UVB rays.7
While SPF works by absorbing, reflecting or scattering the sun's rays on your skin, its protective ability is not linear and does not offer a great deal more protection at higher levels.
SPF Refers Only to Protection Against UVB Rays, Not UVA
In regard to SPF, another important factor to remember is that an SPF rating refers only to protection against UVB rays, which are the rays within the ultraviolet spectrum that allows your body to produce vitamin D in your skin.
But the most dangerous rays, in terms of causing skin damage and cancer are UVA rays. According to EWG:8
"A sunscreen lotion's SPF rating has little to do with the product's ability to shield the skin from UVA rays. As a result of the FDA's restrictions on ingredients and concentrations, U.S. sunscreens offer far less protection against UVA than UVB, particularly those products with the highest SPF.
Because UVA and UVB protection do not harmonize, high-SPF products suppress sunburn much more effectively than other types of sun damage."
Not to mention, studies show that high-SPF products may not offer the SPF they claim. One study found that even small differences in testing conditions of an SPF 100 sunscreen yielded results between SPF 37 and 75.9
The amount of sunscreen applied, sunlight intensity, sweat, swimming and more can all affect how much sun protection you actually receive. There's also evidence that people tend to stay in the sun longer when wearing high-SPF sunscreens, putting them at risk of overexposure.10
No Evidence in Support of Full-Body Screening for Skin Cancer?
The nervousness people experience over threats of skin cancer such as melanoma is augmented by U.S. government intervention that equates sun exposure with skin cancer.11
Yet, at the same time, the U.S. Preventive Services Task Force (USPSTF) says there's not enough evidence that screening for skin cancer can lower skin cancer cases or deaths.
Still, European studies suggest that after public awareness campaigns to inform people about whole body visual screening for skin cancer, the rates of melanoma, the most deadly type of skin cancer, and non-melanoma skin cancers went down, Time reported.12 According to The Washington Post:13
"An editorial accompanying the task force's statement said the 'I' rating [insufficient evidence] does not mean there is not a benefit from screening but that more research is needed to determine if it should be recommended — and, if so, for whom.
… [T]he statement doesn't apply to people who have skin lesions or any other kind of suspicious growths or to those with an increased risk of cancer or a family history of the disease."
Optimal Vitamin D Levels Linked to 65 Percent Lower Risk of Cancer
Another way that wearing sunscreen daily has the potential to increase your cancer risk rather than decrease it is by blocking your body's ability to produce vitamin D.
If you do not get regular sun exposure on your bare skin (or consume a vitamin D3 supplement), there's a good chance you may be vitamin D deficient, which is a risk factor for cancer. One recent study published in PLOS One found vitamin D levels above 40 ng/mL are associated with a more than 65 percent lower risk of cancer. According to the researchers:14
"We found a clear association between 25(OH)D [vitamin D] serum concentration and cancer risk, according to multiple types of analyses. These results suggest the importance of vitamin D for the prevention of cancer. Women with 25(OH)D concentrations ≥40 ng/ml had a significantly lower risk of cancer (~70 [percent]) compared to women with concentrations <20 ng/ml."
Optimizing your vitamin D levels may reduce your risk of as many as 16 different types of cancer, including pancreatic, lung, ovarian, breast, prostate and skin cancers.
Higher Vitamin D Levels at Melanoma Diagnosis May Improve Prognosis
Studies show melanoma mortality actually decreases after UV exposure. Additionally, melanoma lesions do not tend to appear primarily on sun-exposed skin, which is why sunscreens have proven ineffective in preventing it. Exposure to sunlight, particularly UVB, is protective against melanoma (the deadliest form of skin cancer) — or rather, the vitamin D your body produces in response to UVB radiation is protective. The following passage comes from The Lancet:15
"Paradoxically, outdoor workers have a decreased risk of melanoma compared with indoor workers, suggesting that chronic sunlight exposure can have a protective effect."
In another recent study, it was found that vitamin D deficiency at the time of melanoma diagnosis is associated with thicker tumors that likely have a poorer prognosis.16
The researchers believe increasing vitamin D levels to 20 ng/ml or higher (which is actually still a deficiency state) could result in 18 percent of melanoma patients having thinner tumors and therefore improved prognosis. If their levels were increased to optimal levels (50 to 70 ng/ml), it's likely this rate would improve even more.
Oxybenzone: Another Reason Why Many Sunscreens Are Dangerous
Oxybenzone, a popular sunscreen ingredient that has been detected in nearly every American, is believed to cause hormone disruptions and cell damage that may provoke cancer.
This endocrine-disrupting chemical acts like estrogen in your body, alters sperm production in animals and is also associated with endometriosis in women. It has relatively high rates of skin allergy and is a highly skin-penetrating chemical.17 According to the Environmental Working Group (EWG):18
"… [T]he chemical oxybenzone penetrates the skin, gets into the bloodstream and acts like estrogen in the body. It can trigger allergic reactions. Data are preliminary, but studies have found a link between higher concentrations of oxybenzone and health harms.
One study has linked oxybenzone to endometriosis in older women; another found that women with higher levels of oxybenzone during pregnancy had lower birth weight daughters."
There's really no reason to risk exposure to this chemical, as safer alternatives exist. In lieu of the skin-penetrating hormone-disrupting chemicals like oxybenzone, safer sunscreens tend to use non-nanoparticle sized zinc- and titanium-based mineral ingredients, which block the sun's rays without penetrating your skin.
Four Steps to Safely Enjoying the Sun
Applying chemical sunscreens every time you step outdoors may do little to prevent your risk of skin cancer while raising other risks. In addition, you're blocking your body's production of vitamin D and possibly some of sunlight's other health benefits, like its pain-relieving properties. That being said, you don't want to overexpose your skin to the sun and end up with a sunburn, either. To continuously enjoy the positive effects of sun exposure without getting burned, I recommend following these simple safety tips:
1. Protect your face and eyes by wearing a wide-brimmed hat or a cap. The skin around these areas is much thinner than other areas of your body and is more at risk for cosmetic photo damage and premature wrinkling. If it's too hot to protect your skin by covering with light clothing, and you'll be outside for extended periods, be sure to use a natural mineral-based broad-spectrum sunscreen on your skin — these products often contain zinc.
2. Limit your initial sun exposure and slowly work your way up. If you are a fairly light-skinned individual who tends to burn easily, limit your initial exposure to just a few minutes, especially if it is in the middle of summer. The more tanned your skin gets, the longer you can stay in the sun without burning. If it is early or late in the season and/or you are a dark-skinned individual, you could likely safely have 30 minutes on your initial exposure.
3. Build an internal sunscreen with beneficial antioxidants. Astaxanthin, a potent antioxidant, can be used both internally and topically to protect your skin from the sun. You can make your own lotion by adding astaxanthin to organic coconut oil, but be careful of staining your clothing, as astaxanthin is dark red.
Other helpful antioxidants include proanthocyanidins, resveratrol and lycopene. Eating healthy is also important. Fresh, raw, unprocessed foods deliver the nutrients your body needs to maintain a healthy balance of omega-6 and omega-3 oils in your skin, which is your first line of defense against sunburn.
Fresh, raw vegetables also provide your body with an abundance of powerful antioxidants that will help you fight the free radicals caused by sun damage that can lead to burns and cancer.
4. Moisturize your skin naturally. Before sunbathing, apply organic coconut oil on the exposed areas of your skin (as noted above, you could add some astaxanthin to the oil for an added measure of protection). This will not only moisturize your skin to prevent dryness but will also give you additional metabolic benefits.