Men and women cannot live on bread, food and water alone. As it turns out, people might need more Vitamin D than previously thought.

Human bodies require exposure to sunlight to react with cholesterol in the skin to produce vitamin D. As a result, many Americans are missing the nutrient because they live and work indoors and because vitamin D is uncommon in our food supply.

Photo courtesy of Thinkstock images

Recent research has raised concerns among doctors and dietitians that the amount of vitamin D the medical community recommends isn’t high enough.

“There have been a number of papers published calling for an increase in the recommendation for vitamin D, and that’s been going on for three or four years,” said Dr. Allen Knehans of the University of Oklahoma Health Sciences Center. “Clearly, most people aren’t getting 15 minutes of sun exposure per day.”

The vitamin has been shown to have a role in preventing autoimmune diseases, high blood pressure, fibromyalgia, depression, chronic muscle pain, osteoporosis and even some forms of cancer.

“The evidence to me is pretty good that right now in the United States, people who have a low intake of vitamin D have a higher cancer risk,” Knehans said.

Local dietitian Fran Olsen Sharp agrees. “There is good, strong data out there that is really showing that these people who are low in these levels have these diseases.”

Knehans said the recommendation about vitamin D is controversial. “It seems to me to be pretty good evidence that the recommendation should be changed, and we’re not talking about occasionally. There may be some change of 10 percent or something like that. … Even people consuming what is now the recommended intake are still at risk for greater cancer development, for example,” he said.

Years ago, orange juice and milk were fortified with vitamin D and other nutrients, but that was based on outdated dietary information, said Dr. Philip Miner, chairman of the Oklahoma Foundation for Digestive Research. “That was sufficient to block rickets,” he said, but not enough for optimal health.

Miner, Knehans and Sharp agree that outdoor exercise in the daytime is a simple, easy way to give your skin the sun exposure it needs to generate optimal vitamin D levels (provided your dietary intake is adequate).

But OU Physicians dermatologist Dr. Pamela Allen contests them.

“There’s a lot of safer alternatives to get your vitamin D that (dermatologists) would promote,” she said.

Cod liver oil and oily fishes are the most common, as well as a specific vitamin D supplement, because the nutrient is underrepresented in most multivitamins.

Allen said the skin must reach a hint of redness (known as erythema) to generate vitamin D production. That condition that, when repeated over time, is associated with skin cancer, she said.

“Something like 15 minutes a day of sun exposure would be a significant contribution to vitamin D production,” Knehans said.

Sharp and Allen both recommended that people request their vitamin D levels be checked at their next health checkup, and Knehans strongly advised consulting a doctor before using any kind of supplement, because of the risk of toxicity caused by overconsumption.

“It’s a balancing act of reducing cancer by getting adequate vitamin D production through sunlight exposure and not increasing exposure so much that you increase risk of skin cancer,” Knehans said. “In the nutrition business, moderation is always the mantra.”