In Hawaii, weekends are synonymous with beach days and outdoor picnics. You would think getting enough sun exposure — and the vitamin D that comes with it — would be easy.

Local health-care professionals say otherwise.

“If I would have to guess, I would say for the majority of people in Hawaii, if you check their vitamin D level, (it) is going to be low,” said Dr. Landis Lum, a family practice physician at Kaiser Permanente. Some are deficient enough to require supplements.

Vitamin D is essential for calcium absorption and is associated with strong bones. It also helps boost immunity and cardiovascular health, said Lum. The easiest way to absorb vitamin D is through the sun, but it is also found in fortified milk and other foods.

There’s some debate about what the optimal vitamin level should be. Dr. Jennifer Loh, an endocrinologist at Kaiser Permanente, says she recommends her patients spend five to 10 minutes without sunscreen under direct sunlight between 10 a.m. and 3 p.m. twice a week.

“It’s a myth that vitamin D deficiency doesn’t exist in Hawaii. We definitely have vitamin D deficiency, especially in our elderly population…also in our little babies and infants,” Loh said.

Nationally, three out of four adolescents and adults in the United States lack vitamin D, according to a study published in the Archives of Internal Medicine in March 2009.

Even sunny Hawaii is not immune. One in five of Loh’s Hawaii patients are deficient enough to require supplements and mandated sun time.

Some stay out of the sun because it’s hot. Other sunbathers are apparently too diligent in applying sunscreen or avoiding the sun altogether — the result of years of successful skin cancer awareness.

Optimal Vitamin D Levels Debated

To measure vitamin D, doctors administer a blood test analyzing a patient’s “25-hydroxyvitamin D level.”

But even within the scientific community there’s an ongoing debate about what optimum vitamin D levels should be.

The Vitamin D Council, a non-profit educational organization recommends 25-hydroxyvitamin D levels of 50 ng/ml to 80 ng/ml. However, a 2007 article in the New England Journal of Medicine spells out much lower standards: 30 ng/ml to 40 ng/ml 25-hydroxyvitamin D level is optimal and less than 20 ng/ml is deficient.

“What happens when vitamin D goes low is that the body produces a hormone called parathyroid hormone and this steals calcium out of the bones,” said Dr. Michael Bornemann, an endocrinologist in private practice and associate clinical professor at the John A. Burns School of Medicine. “This is what leads to a lot of the problems with vitamin D deficiency and it is thought that 30 (ng/ml) is kind of the break point for that. If you have vitamin D below 30 (ng/ml) then you are going to have elevated levels of this hormone.”

One of the studies suggesting that accepted vitamin D recommendations are too high took place right here in Hawaii.

In 2007, Dr. Neil Binkley, a faculty member at the University of Wisconsin School of Medicine and Public Health, co-wrote a Hawaii based study titled “Low Vitamin D Status despite Abundant Sun Exposure.”

The study looked at vitamin D levels in 93 participants who were over 18-years-old from the University of Hawaii at Manoa and customers of Aala Park Board Shop. Of the sample, 63 were male and 30 were female. Subjects reported spending an average of 22.4 hours a week with no sunscreen, and 28.9 hours a week with and without sunscreen. After testing their blood, the results show that despite “more than adequate sun exposure,” 51 percent of the participants had low vitamin D levels. The study assumed the optimal level of vitamin D to be 30 ng/ml.

All the participants were active, sun-loving adults, but more than half could not get enough sun exposure. The findings have led one of the study’s co-authors to question whether standard vitamin measurement levels are too high.

“The bottom line is the levels people are suggesting we need may be too high,” said Rachel Novotny, co-author of the study and a faculty member in the department of Human Nutrition, Food and Animal Sciences at the University of Hawaii at Manoa. “It would seem logical that the level people have when they are in the sun a lot would be an optimal level. If you can’t get anymore, how can you say that we need more.”

Vitamin D Doesn’t Come With an Office Job

Larry Lusk, a 48-year-old property manager for Kahala Beach Cove, was diagnosed with vitamin D deficiency six months ago. During a routine check up, his doctor suggested he get a blood test to measure his 25-hydroxyvitamin D level. The test results were very low: 14 ng/ml. Lusk said he was “100 percent shocked.”

Before his visit, Lusk said he merely felt tired, which he attributed to his allergies and overworking.

“One of my first questions was, geez all my life I have been brought up to believe that our skin produces vitamin D via the sunshine and over here we have plenty of sunshine. What’s up?” Lusk said.

Before the diagnosis, he said the majority of his time was spent indoors. Aside from walking to and from his car, he walked on the beach two to three times a week at night.

The “High Risk” Categories

Lum, the Kaiser family physician, says he advises all of his patients who are over 40 or overweight to test their 25-hydroxyvitamin D levels.

“Many people who are overweight have vitamin D deficiency. One of the reasons is because vitamin D is fat soluble, so it gets stored up in their fat tissue,” Lum said. “Less is available in their blood, so they have lower vitamin D levels.”

The elderly and infants also run a higher risk of being vitamin D deficient because they are usually stuck indoors.

The elderly are at risk “because they do not go outside anymore and they are in care homes in Hawaii,” Loh said. “They just stay indoors all of the time and they do not get any sunlight. And then our little infants, especially those who are solely breast-fed. There is not a lot of vitamin D in breast milk so they don’t get anything from their food.”

Too Much Sunscreen

One of the most surprising factors contributing to vitamin D problems is the years-long successful campaign raising awareness about skin cancer. As it turns out, people are using a lot of sunscreen — sometimes too much, doctors say.

Nileen Mattos, a 48-year-old business management officer for Kaiser Permanente, went to the doctor one year ago with pain in her knees, ankles, bones, fatigue and swelling. Her doctor said she was vitamin D deficient.

“I was not surprised that I didn’t have vitamin D from being in the sun,” Mattos said. “But I was surprised that I was vitamin D deficient.”

She used to be an avid equestrian but changed her outdoor routine after she noticed sunspots on her arms. Now, she tries to avoid the sun and applies 30 SPF sunscreen to her skin every morning.

“I noticed when I go out in the sun those sunspots start to appear more. Then I was worried that I was going to get skin cancer,” Mattos said.

However, even sunscreen with 15 SPF can absorb 93 percent of ultraviolet radiation while 34 SPF can absorb 97 percent, according to the American Melanoma Foundation.

Since her diagnosis, Mattos has been taking prescription vitamin D supplements and spending two hours everyday in the sun, just to be safe. But she still refuses to nix the sunscreen.

Getting Enough Vitamin D

The best (and cheapest) source of vitamin D is sunlight, but there are a few other ways to absorb it, says Bornemann, the endocrinologist in private practice and associate clinical professor at the John A. Burns School of Medicine.

Among food products loaded with vitamin D, topping the list are wild sockeye salmon, cod liver oil, fresh shiitake mushrooms, egg products, fortified milk and cereal.

In food and supplements, vitamin D is measured in international units (IU) versus nanograms per millileter in the blood stream.

About five and a half ounces of wild cooked sockeye salmon fillet contains 1448 IU of vitamin D. This is 724 percent more than the suggested dose of vitamin D for children and adults younger than 50-years-old.

For adults between the ages of 51 to 70-years-old, the suggested daily dosage is 400 IU of vitamin D, 600 IU for adults 71-years-old and older, and 800 IU to 1,000 IU for those who do not have adequate sun exposure, according to data from the New England Medical Journal of Medicine and the Office of Dietary Supplements.

A limited list of foods high in vitamin D are available on the U.S. Department of Agriculture’s National Nutrient Database for Standard Reference.

On the mainland where sun is not available all year round, vitamin D deficiency is more prevalent than in Hawaii, said Loh, the Kaiser endocrinologist. But those in Hawaii aren’t exempt, she said.

“That’s more of what we are trying to dispel is (this idea) that we can’t get vitamin D deficiency or you don’t need vitamin D supplementation because you live in Hawaii—because a lot of people do,” Loh said.