Sunny D: Vitamin beats C in combating cold, flu |

Sunny D: Vitamin beats C in combating cold, flu

Jennifer Brown
The Denver Post

Rethink orange juice and lozenges infused with vitamin C for staving off colds and the flu. Perhaps the answer is in the sunshine.

Vitamin D, available for free in the sun’s rays, boosts immunity, according to the largest and most nationally representative study so far on the subject.

Sunlight is a major source of vitamin D, which could explain why people are more likely to get sick in the winter, said Dr. Adit Ginde, a University of Colorado Denver surgery professor and lead author of the study.

For decades, people have turned to vitamin C to prevent respiratory infections. Vitamin C has many health benefits, but there is little scientific evidence it protects people from the common cold.

“It gets out in the lay public and just gets self-perpetuated,” Ginde said. “It’s one of those things that people say, ‘It doesn’t hurt to take more.’ “

Point isn’t to “debunk” C

Ginde said the point of the study, done in conjunction with Harvard Medical School, is not to “debunk vitamin C.” Rather, it provides the best evidence to date linking vitamin D ” commonly associated with strong bones ” to immunity.

The study examined vitamin D levels in the blood of 19,000 people, using samples collected by the National Center for Health Statistics. People with the lowest levels of the vitamin were about 40 percent more likely to have had a recent respiratory infection.

And people with asthma or emphysema were even more likely to get sick when their vitamin D levels were low.

Vitamin D appears to interact with cells that are important to immunity. Without enough of the vitamin, those cells are not as effective in killing common bacteria and viruses.

“The science surrounding vitamin D has really expanded over the last couple of years,” Ginde said.

Still, the study authors said clinical trials must confirm their results before vitamin D is recommended to prevent colds and flu.

Foods that contain vitamin D include milk, salmon, sardines, shrimp and eggs. But “10 minutes in the sun would far surpass your intake of vitamin D” compared with diet choices, Ginde said.

It’s nearly impossible for people living north of Atlanta to get enough vitamin D through sunlight year-round because of Earth’s tilt. In the winter, northern dwellers should take supplements, and in the summer, some scientists recommend 20 minutes of sun per day ” without sunscreen.

The CU study appears in Monday’s issue of Archives of Internal Medicine.

The study is “totally predictable” and adds to the “body of evidence” proving vitamin D’s infection-fighting power, said Dr. Bruce Hollis, a Medical University of South Carolina professor who is a leading expert on vitamin D. He was not involved in the research.

Hollis, who takes 4,000 units of vitamin D daily, said he is frustrated by the government’s daily recommended allowance of vitamin D: 200 units. He called the amount in a daily vitamin “totally meaningless.”

“It’s nothing,” he said. “It’s absolutely worthless.”

Hollis said vitamin C is overrated when it comes to immunity.

Information “taken as gospel”

“It’s what people thought, what people would say, then it ends up in textbooks and is taken as gospel,” he said.

A 2007 report from the Cochrane Collaboration, which evaluates medical research, concluded that “regular ingestion of vitamin C has no effect on common cold incidence in the ordinary population.” The group reviewed 30 trials involving 11,350 people.

Researchers at the Linus Pauling Institute ” named for the late author of “Vitamin C and the Common Cold” ” say most vitamin C studies have not used high enough doses.

Vitamin C Foundation co-founder Owen Fonorow said taking large amounts of the vitamin ” 8,000 milligrams every 20 minutes, way more than in lozenges or vitamins ” can cut the intensity of a cold.

But even he takes a vitamin D supplement.

“I’ve turned into a vitamin D believer ” four or five winters without even a sniffle,” he said. “There is something almost miraculous.”

But Dr. Bruce Ames, a micronutrient scientist at Children’s Hospital Oakland Research Institute, said focusing on one vitamin is pointless.

A lot needed to survive

People need about 40 compounds ” including vitamins, minerals and amino acids ” to survive. At least 80 percent of Americans are deficient in at least one compound and not all of them are even included in multivitamins, let alone at the necessary dosage, Ames said.

The body rebalances its metabolism when it’s deficient in one of the compounds, then DNA can become damaged, setting a person up for cancer and other degenerative diseases later in life.

“All of these studies are saying this vitamin will do this or that,” Ames said. “You have to take the whole picture into account.”

Jennifer Brown: 303-954-1593 or

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