An expert dietary panel increased the recommended daily intake of vitamin D last week, even doubling the amount that seniors should get in their diets.

But its report also created confusion about whether vitamin D supplements that have become popular in recent years are still a good idea.

A Scarborough-based doctor who was on the national study panel said supplements do make sense — but within reason.

“A little bit of supplement is not going to hurt you, and 200 to 400 (international units) in multivitamins, I think that we shouldn’t discourage that,” said Clifford Rosen, a bone specialist at the Maine Medical Center Research Institute who served on the Institute of Medicine panel.

“The real issue is, how about the people taking 5,000 or 6,000 units? We found no evidence to support the contention that more is better.”

The institute, which advises the government on nutrient levels and spent two years reviewing vitamin D research, said adults need about 600 units a day, while seniors need 800.

That’s more than the old recommended amount, but much less than many people expected the panel to recommend. The last official recommendation was 400 units for everyone, Rosen said.

The panel also suggested that, with some effort, Americans can get enough of the nutrient from diet and sunlight, which helps the body make natural vitamin D.

Many Americans have started to take large doses of the vitamin — 2,000 units a day or more — based on reports that Americans are chronically deficient. And while there is a clear link between vitamin D and bone health, recent research also suggested that vitamin D deficiency could increase the risks of cancer, heart disease and other illnesses.

In its new report, the federal panel said hundreds of studies on connections to illnesses other than bone weakness “provided often mixed and inconclusive results and could not be considered reliable.”

While many were expecting a stronger link to other illnesses, the new report will not settle that debate. Scientists are already looking for more proof. “There’s just not enough evidence yet to support that contention,” Rosen said.

On the other hand, the report suggested that people may have gone too far with the supplements. There also is some evidence, although also not conclusive, that too much vitamin D can increase risks of bone fractures and other health problems, it said.

Even though American diets don’t generally provide the recommended amounts, most people do have enough vitamin D in their bodies, the panel said. That’s likely because they are making it naturally after being out in the sun, and because of multivitamins, Rosen said.

“The bottom-line message from the Institute of Medicine is that most people are doing well and meeting the requirement, but they are meeting it in different ways,” he said. “Not everybody needs supplements.”

The biggest increase in the recommended dietary allowance is for seniors because there is a clear link between osteoporosis and bone fractures. “That’s where we found the strongest evidence,” he said.

Alison Fernald, a registered dietitian in Brunswick, said the new recommendations seem to make sense, including advice that people get their blood tested before taking large supplements.

“I suggest that people have their vitamin D levels checked,” she said. If the levels are low, she recommends a larger supplement to correct the deficiency and then a smaller supplement with 400 to 1,000 units, depending on a patient’s bone health.

“With a lot of nutrients, the consequences of too little are the same as the consequences of too much. So it’s a moderation game, even with vitamin D,” she said.

Mainers have to be especially mindful of their vitamin D intake in winter because of the lack of exposure to the sun, Fernald said.

“The whole Northern belt is at risk” of being vitamin D-deficient, she said. “The sunshine doesn’t reach us for as long, and it’s not as strong.”

There is some winter effect on vitamin D levels, Rosen agreed. But Mainers also have access to fresh seafood, such as salmon, that is rich in vitamin D.

A bigger problem for Mainers is their weight, according to Rosen.

Because vitamin D is fat-soluble, an overweight body will store the nutrient rather than letting it get into the blood.

“I think the bigger problem in Maine is the rates of obesity,” he said. “If we can keep your weight down we can increase your vitamin D.”

Staff Writer John Richardson can be contacted at 791-6324 or at:

jrichardson@pressherald.com