You’ve probably heard that eating chocolate causes acne. Or that drinking plenty of water will help your skin look healthier, maybe even smooth out a few wrinkles. Or perhaps that loading up on antioxidant-rich foods may undo some of the damage from those years of sun worship. But are any of these beliefs actually true?
Dermatologists have long dismissed many such notions as myths, but now some researchers are starting to think there may be a degree of truth behind at least one of them.
A recent study suggesting a link between diet and acne has “created a tidal wave in the dermatology community,” says Loren Cordain, a professor of health and exercise science at Colorado State University in Fort Collins.
“If you look at the medical textbooks on dermatology, specifically the medical texts on acne, it’s spelled out loud and clear that diet has no effect on acne,” he says.
But in the study, Cordain and colleagues concluded that consumption of candy bars, potato chip, cookies, doughnuts, cakes, soda, pizza, white breads and other processed sugary and starchy foods common to Western cultures may indeed have an effect.
The researchers arrived at their findings after studying 1,200 Kitavan Islanders of Papua New Guinea, including 300 between the ages of 15 to 25, and 115 Ache hunter-gatherers of Paraguay, including 15 between the ages of 15 to 25.
“We didn’t find a single case of acne,” Cordain says.
That’s in stark contrast to the United States, where about 80 percent to 95 percent of teens develop acne and even middle-aged adults aren’t immune.
Refined carbos to blame?
In search of an explanation, the researchers examined the diets of the two primitive cultures. The Kitavan Islanders ate mostly fish, fruit, tubers and almost no processed foods, while the Ache hunter-gatherers consumed primarily vegetables, peanuts, rice, some wild game and only a small amount of pasta, bread and sugar.
Cordain strongly believes their diet is the reason they had no acne. Specifically, they rarely ate refined carbohydrates like breads and sweets that have a “high glycemic load” — meaning they cause blood sugar levels to surge.
A steady diet of such foods can trigger a “hormonal cascade” that leads to acne, according to Cordain’s theory. High blood sugar levels cause the pancreas to pump out more insulin, which triggers the release of male hormones and growth factors. In the end, Cordain says, more oil is produced and more skin cells slough off, clogging pores.
Don't miss these Health stories
More women opting for preventive mastectomy - but should they be?
Rates of women who are opting for preventive mastectomies, such as Angeline Jolie, have increased by an estimated 50 percent in recent years, experts say. But many doctors are puzzled because the operation doesn't carry a 100 percent guarantee, it's major surgery -- and women have other options, from a once-a-day pill to careful monitoring.
- Larry Page's damaged vocal cords: Treatment comes with trade-offs
- Report questioning salt guidelines riles heart experts
- CDC: 2012 was deadliest year for West Nile in US
- What stresses moms most? Themselves, survey says
- More women opting for preventive mastectomy - but should they be?
While it’s possible that good genes help these populations have clear skin, he says, other groups of Pacific Islanders and South American Indians who move to areas where Western diets are common develop acne. Previous observations have indicated the same thing happened when Eskimos started eating Western foods.
Since the publication of Cordain’s study last winter in the Archives of Dermatology, he says he’s heard from dozens of patients and dermatologists who believe there’s truth to his belief.
Jury still out
But Alexa Boer Kimball, an assistant professor of dermatology at Stanford University, says the jury is still out on the diet-acne link.
“Typically we advise patients that your diet does not affect your acne,” says Kimball.
“This (study) reopened the discussion but it has certainly not been concluded one way or the other,” she says.
Another potential reason the people in the study didn’t have acne is that they are regularly exposed to the sun, which can counter the skin condition, she points out. Doctors, however, don’t advise sunbathing to remedy acne because sun damages the skin in ways that lead to wrinkling and skin cancer.
For its part, the American Academy of Dermatology maintains that acne is not caused by foods. But the group emphasizes the importance of a balanced diet and notes that dermatologists have differing opinions on the subject.
One of them is Dr. Karen Burke, who has a private practice in New York City.
“I do think that some foods cause acne,” Burke says.
When patients come in complaining of breakouts, she asks them if their diet has changed recently. Foods that appear to act as culprits are chocolate, nuts, potato chips, soda, yogurt and other dairy products, and iodine-containing foods like shellfish and spinach, she says.
Cordain says studies are currently underway in Australia and Sweden to see if people who switch from a high-glycemic-load diet to one that has few of those foods, but plenty of fruits, vegetables, fish and lean meat, can in fact get rid of their acne.
Antioxidants and aging skin
It’s also unclear whether certain diets or dietary supplements can help reverse signs of aging and even prevent skin cancer.
Animal studies have suggested that consuming vitamins such as C and E can help counter sun damage, but equivalent human studies have not been done. And based on the doses that were effective in animals, it would be difficult for people to get the same amounts through food alone, says Burke, who recommends vitamin E and C supplements to her patients.
Kimball sees no harm in a daily multivitamin supplement, but doesn’t recommend anything beyond that.
“There are no good studies to say if you take these things orally they’re protective,” she says.
As for other dietary supplements, there’s some evidence that evening primrose oil may help people with atopic dermatitis, while fish oil supplements may aid those with psoriasis, Kimball says.
And people with extreme dietary deficiencies may need vitamin supplements to prevent or treat certain diseases, she notes. For example, a niacin deficiency can lead to pellagra, a condition that causes scaly sores on the skin, while a lack of vitamin C can cause scurvy, which also produces skin lesions.
Potentially harmful supplements
Meanwhile, some supplements can have adverse effects on the skin. Both gingko biloba and tea tree oil have been linked with rashes, according to Kimball. And St. John’s wort can make people more sensitive to the effects of the sun, she warns.
As for other ways diet may affect the skin, Burke says people who eat very little fat may experience dry skin.
“You need a little bit of oil in your diet,” she says.
And for people with food allergies, consuming even trace amounts of an offending food — be it shellfish or strawberries — can trigger a host of symptoms including hives and itchy skin.
So what about the advice to drink plenty of water to improve the look of your skin?
“The whole water thing, as far as we can tell, is one big myth,” Kimball says.
© 2013 msnbc.com Reprints