Arlene Peterson recently joined the growing number of people diagnosed with a vitamin D deficiency.

“It was a little bit confusing since I’ve been in South Florida and I feel like I’m constantly in the sun or running away from the sun,” she said. “Maybe that’s the problem.”

Believe it or not, vitamin D appears to be lacking in sunny Miami, as Dr. Silvina Levis’ research found.

“We have been very surprised because there’s more people in our South Florida area that have low vitamin D levels than we would have thought,” said Levis, who is director of the Osteoporosis Center at the University of Miami Health System.

Large population studies have shown that people with lower vitamin D levels “have higher incidence of certain diseases like cancer, diabetes, and high blood pressure,” Levis said.

Only a simple blood test is needed to get your vitamin D level. When the levels are measured in nanograms, 30 to 100 is sufficient, 11 to 29 is insufficient, and 10 and lower is deficient. Levis says anything under 30 is a concern.

In addition, there are many Vitamin D capsules and pills on the market, and a wide variety of doses.

The Institute of Medicine recommends 600 international units a day for most people, and 800 if you are 71 or older.

If you are deficient, however, you might have to take thousands of units a day.

In Peterson’s case, clothes and sunscreen protect her skin but also block Vitamin D production. So she is being prescribed 50,000 units a week to get her to a healthy level.

“The doctor said my Vitamin D is low, very low,” she said, “so I now have to take supplements.”