How to get enough Vitamin D as we head back outdoors

As Chicagoans burst out of their coronavirus stay-at-home cocoons, experts say it’s OK to soak up the sun and its vitamin D-filled ultraviolet rays without sunscreen — but in moderation and preferably at certain times.

“Researchers suggest five to 30 minutes in the sun, from 10 a.m. to 3 p.m., at least twice a week can lead to vitamin D synthesis — on your face, arms, legs and back — without sunscreen,” said Dr. Kristi Tough DeSapri, assistant professor of obstetrics and gynecology and internal medicine at Northwestern University’s Feinberg School of Medicine.

But it’s a balancing act. Greater sun exposure can lead to cellular damage, and repeated sunburns to skin cancer. So, after that initial run in the sun, wear a hat and sunglasses, and slather on the sunscreen.

Yet people who live in a Northern climate like Chicago’s — as well as Blacks and others with dark skin pigmentation in particular — need more than direct sunlight to get enough vitamin D to help the body absorb calcium, research shows.

Vitamin D deficiency can cause children to have soft bones, stunted growth and skeletal deformities, and, in adults, can lead to osteoporosis and increased risk of bone fractures, appears to worsen COVID-19 mortality and has been linked to aggressive prostate cancer.

Insufficient vitamin D also can cause muscle pain, body aches and feeling run down, said Dr. Mark Loafman, chair of the Department of Family Medicine at Cook County Health.

“Every spring, up to one-third of the population is vitamin D deficient emerging from winter,” he said.

Studies show 42 percent of Americans are vitamin D deficient. Blacks and Latino populations are at highest risk because high amounts of melanin pigment in skin reduce the body’s ability to produce vitamin D from sunlight, according to a study in Nutrition Journal.

The answer? “It’s boring, but it’s affordable: Buy fresh fruits and vegetables, and make them part of your daily diet,” Loafman said.

“The only people who benefit from the multi-billion dollar supplement industry [are] the people who sell the supplements,” he said. “Trying to get ‘super’ levels doesn’t work. It’s wishful thinking, and it can be harmful.”

Too much vitamin D can cause a person’s body to absorb excessive calcium, which risks bone pain and kidney stones.

Yet many people find it difficult to eat enough quantities of foods such as oranges, tuna, salmon, mackerel, fish oil, egg yolks and fortified milk or yogurt — all rich in vitamin D — to sustain the recommended levels.

You can take supplements — but with care. The recommended daily allowance, including food and supplements, is 400 international units a day for babies up to 12 months, 600 IUs for ages 1 to 70 and 800 to 1,000 IUs for people over 70 or those susceptible to fractures, according to the Institute of Medicine of The National Academies.

People who are deficient require higher daily or monthly doses.

Doctors don’t routinely check for vitamin D levels when they do blood tests, so people should speak up if they’re worried about having brittle bones. Women are particularly susceptible to bone loss after menopause because they reach their peak bone mass in their 20s, according to Tough DeSapri.

Cook County Health

Still, vitamin D’s benefits are largely unexplored. Recent research doesn’t support its ability to prevent cancer, heart disease and respiratory system attacks. But vitamin D might support immune function.

Dr. David Meltzer, chief of the hospital medical section at the University of Chicago, is starting trials to see whether vitamin D can boost the body’s immune system to fight off COVID-19. His studies will include the general public and people at higher risk for the coronavirus, including health workers, police, firefighters and other first-responders.

Meltzer wants to get 10,000 or more Chicagoans to sign up online for one of the trials. The participants will take vitamin D for a year but won’t know the amount. Some will get a low dose, others a higher one.

The beauty of such a test, according to Meltzer, is its relatively low cost and potentially high return.

“This is something we can do together that might help all of us,” he said. “If we do a large enough randomized trial, we could get an answer in a few months.”

Sandra Guy is a freelance writer.