Vitamin D: What it says on label may be wrong

PORTLAND, Ore. -- If you're one of the millions who take Vitamin D supplements in the winter, don't let the label fool you.

A new study released on Monday shows a wide variety of discrepancies between the potency and what it says on the bottle.

The study, performed at Kaiser Permanente in Portland, examined 55 bottles of over-the-counter Vitamin D supplements from 12 different manufacturers.

"Some manufacturers were more variable than others," said Dr. Erin LeBlanc, a researcher of Vitamin D dosages. "We also found that even within the same pill bottle you could find a range."

For instance, one pill was labeled to have 1,000 units of Vitamin D; it actually had 1,460. Another pill labeled to have less -- only 90 units of the vitamin.

Vitamin D is often recommended to Pacific Northwesterners in the winter months, when the days get shorter and sunlight is scant. The vitamin helps strengthen bones and can help with weight loss, sleep and mood.

Pat Cunningham is one of the people who take vitamin supplements because he has osteoporosis.

Presented with the new study, Cunningham was baffled.

"That blows me away," Cunningham said. "I mean, who can you trust?"

The discrepancy in dosages is also troubling to health experts.

"They're not getting the amount of Vitamin D that they or their doctor think they need," LeBlanc said.

So short of testing supplements yourself, how can you make sure you're getting the dosage on the label? Well, the study found those bottles with the designation, USP, were the most accurate. Manufacturers pay for that extra verification.

The vitamin brands come with the extra verification include Equaline at Albertson's, Kirkland at Costco and Nature Made, which is sold at many grocery and drug stores.

Safeway's Calcium Plus Vitamin D has the USP designation, but its regular Vitamin D does not.