Blondes may have more fun, but researchers say redheads may soak up more sun. Experts from the ScotlandsDNA project speculate that people with ginger colored hair have a genetic advantage in gloomier climates because they can create more vitamin D in low-light conditions than peers with darker skin or hair.
While about 2% of the population has red hair, about 13% of people in Scotland are gingers.
"I think it’s to do with sunshine. We all need vitamin D from sunshine, but Scotland is cloudy,” Alastair Moffat, the project’s managing director told the British newspaper, The Daily Mail. “We have an Atlantic climate and we need light skin to get as much vitamin D from the sun as possible.”
Vitamin D is often dubbed the sunshine vitamin because the body produces it in response to sun exposure. It's also found in fortified dairy and cereals, fatty fish, and egg yolks.
Pale skinned people are the most efficient at making vitamin D from their time in the sun whereas dark-skinned people take longer to make the same amount. Studies show African Americans who avoid sunshine and eat a vitamin D deficient diet tend to have much lower levels of the vitamin in their blood than people with paler skin, something registered dietitian Katherine Farrell Harris warns could be a health hazard.
Farrell Harris says a fair skinned person might benefit from 10-15 minutes of daily sun exposure, but someone with a lot of skin pigmentation might need several hours to absorb adequate amounts of the vitamin. Considering wrinkling and skin cancer risks, it’s not responsible to make such recommendations, she says.
Unfortunately, most people aren’t getting enough D from the diet either. Farrell Harris says she sees people of all ages and colors in her practice that are vitamin D-deficient. Supplements can make up the difference, but she cautions against popping pills without a trip to the doctor to get your blood levels checked first. Recent research suggests many people take vitamin D supplements when they don't need them.
“If you're low in vitamin D, your doctor can recommend the appropriate amount of supplementation you need,” she says. “In some cases that may require mega-dosing but you definitely don’t want to self-prescribe.”
Regardless of skin color, everyone needs the same amount of vitamin D for good health. The National Institutes of Health suggests 600 IU of the vitamin for men and women up to age 70 and 800 IU for those aged 71 and up.