Besides being chock full of essential nutrients like vitamins A, C and B, new lab research suggests strawberries might also, in the future, play a part in protecting against dangerous UV rays.
Spanish and Italian researchers found that putting strawberry extract on skin cells helped to protect the cells from UVA damage.
The researchers speculated that the protective powers may lie in strawberries' anthocyanins (previously linked with a decreased diabetes risk), which are what make strawberries red.
"These compounds have important anti-inflammatory, antioxidant and anti-tumour properties and are capable of modulating enzymatic processes," study researcher Sara Tulipani of the University of Barcelona, said in a statement. However, "we have not yet found a direct relationship between their presence and photoprotective properties."
"At the moment the results act as the basis for future studies evaluating the 'bioavailability' and 'bioactivity' of anthocyanins in the dermis and epidermis layers of the human skin, whether by adding them to formulations for external use or by ingesting the fruit itself," Tulipani added.
In the Journal of Agricultural Food Chemistry study, researchers added strawberry extract in different doses -- 0.05 milligrams per milliliter, 0.25 milligrams per milliliter and 0.5 milligrams per milliliter -- to skin cell cultures. They also had a control extract added to the skin cell cultures.
Then, the researchers exposed those skin cell cultures to ultraviolet light that is equivalent to 90 minutes of mid-day sun in the summertime.
The study authors found that adding the strawberry extract, especially at the highest dose, to the skin cell cultures seemed to help decrease DNA damage and help to preserve the cells' survival, compared with the controls.
It's important to note that the findings are only in skin cell cultures, and not in actual humans -- more research will be needed to tell if strawberries will actually be viable as a skin protectant (and in what form).
But in the meantime, here's what we do know from dermatologists about protecting our skin from ultraviolet rays:
Sunscreens follow one of two formulas. So-called "chemical free" sunscreens are made with a heavy metal -- usually oxidized zinc, though sometimes titanium oxide. Zinc and titanium sit on the surface of the skin, serving as a reflective, protective cover against damaging sun rays. Think of them almost like a giant reflector, says Dr. Darrell Rigel, Clinical Professor of Dermatology at New York University Medical Center. "They're just like a mirror, reflecting ultraviolet light off," he says. The other type of sunscreen is typically made with the chemical Oxybenzone, and is referred to as "organic" or "chemical" sunscreen.
Some people prefer chemical-free sunscreens to the more common lotions and sprays, made with Oxybenzone. That's because old research in rodents has shown a relationship between oxybenzone and melanoma, though the link is inconclusive and most accredited medical organizations do not consider it viable. Additionally, oxybenzone is an endocrine disruptor that mimics estrogen -- a concern for many people who try to avoid synthetic hormones. "Oxybenzone is one of the oldest and most used sunscreen ingredients in the world, having been in use since the 1970s, and to date there have been no human cases of hormonal disruption documented," says Dr. Jessica J. Krant, MD, MPH, founder of the Art of Dermatology in New York City, and an assistant clinical professor of dermatology at SUNY Downstate Medical Center.
While the cancer link to oxybenzone isn't clear, there are other reasons a person might not want to use a chemical-based sunscreen: first of all, they have a shorter half-life, according to Rigel. Their protection begins to degrade after two hours, compared to zinc-based lotions' eight hours. But Zinc and titanium lotions are by no means perfect: because they sit on the surface of the skin, they are less resistant to water. Swimmers and other active people will have to reapply frequently. Additionally, as they degrade, the metals form clumps on the skin's surface -- this leads to patches of protected skin and patches without any protection at all. By contrast, oxybenzone-based creams degrade evenly. One additional problem with zinc and titanium based creams? They don't look great. Especially for the dark complected among us, the metal formulas can leave a noticeable white coating. If aesthetics are a concern, a beachgoer may forgo the lotion altogether -- and that's the only form of unacceptible sunscreen: none. "Honestly, the best sunscreen is whatever the patient uses," says Dr. Bobby Buka, a dermatologist in private practice in New York City. "I'm not going to fight the battle about formulation."
While some sun lotions may offer SPFs as low as two, the general consensus is that, to be effective, a lotion must have an SPF of at least 15, though the American Academy of Dermatology recommends a sunscreen with an SPF of 30 or more. "Remember this only applies to UVB coverage and requires sufficient amounts," cautions Krant.
SPF applies only to UVB rays, but we now know that UVA rays can be just as damaging -- and may be even more closely associated with premature skin aging. The new FDA label regulations require manufacturers to rate their UVA protection on a scale of five stars, but until those rules go into effect next year, make sure you look for a broad-spectrum sunscreen that protects against both types of ultraviolet rays. Though beware: broad-spectrum doesn't necessarily mean you're in the clear. As Rigel explains, companies need only provide a tiny amount of UVA protection to give their product that label. "What's really important is proportionality," he explains, and that's factored into the future labels, but not the current ones. Using the current labels, "you'd basically have to be organic chemists to figure it out," Rigler says. Any label that discusses proportionality or the test used to arrive at UVA protection scoring, the critical wavelength test, may be the best bet.
There's no such thing as waterproof sunscreen. In fact, the new FDA guidelines will require that sunblocks reduce their claims to "water resistant," "water resistant 40" and "water resistant 80." The numbers connote how many minutes they are able to uphold protection after getting wet. Older bottles may still say "waterproof," but don't believe the hype. If you're spending a great deal of time splashing around -- or you happen to sweat more than the average person, up your frequency of applications.
Most recommendations suggest reapplying every two hours, because that's the point of degradation for oxybenzone-based sunscreens, which are the most common. But a zinc sunscreen can be applied every four, six or even eight hours, according to Dr. Bobby Buka. However, as Buka explains, all testing of sunscreens is done at a higher concentration that we don't replicate on the beach, at two milligrams per square centimeter. Given that discrepancy, it's better to reapply more frequently -- and that's especially true for those who are sweating, swimming or otherwise exposing their skin to water. The American Academy of Dermatology recommends using about one ounce (enough to fill a shot glass) to cover all exposed parts of the body, though that should be adjusted based on size.
Sometimes. Oxybenzone-based sunscreens need that long to penetrate the dermis and become active. But if you're wearing a barrier sunscreen like zinc, you're ready to go as soon as you apply.
Yes. Sprays, lotions, oils -- whatever you truly use, as long as you are thorough, is a good product, agreed the experts. People who use sprays are slightly more likely to miss some spots, so Rigel recommends spraying two coats.