The "Sunshine Vitamin" : Too Little Vitamin D Can Leave You Feeling Sluggish

SIOUX FALLS (Dec. 1, 2009) - The best source of Vitamin D doesn't come from what's in a carton, can or even a capsule - it comes from the sun.

Yet for many reasons, people can become deficient in this essential vitamin. First is our location in the Northern Hemisphere, where winters are longer and days are shorter. Second, many people work indoors and don't see much of the sun, especially in the winter months. Third, because of skin cancer danger, people are more likely to avoid direct sunlight and wear sunscreen and protective clothing. "Especially in the winter months of November through March, most people living in the Midwest are deficient in Vitamin D," said Dr. Wael Eid, endocrinologist with Avera Endocrinology.

Vitamin D is actually a hormone, produced when sunlight strikes 7-dehydrocholesterol in the skin. It is associated with a number of body functions, one of which is helping the bones absorb calcium. Vitamin D deficiency causes symptoms such as fatigue, body aches, cramps, charley horses, restless legs, and tingling and numbness in the hands and feet, Dr. Eid said. Deficiency is also associated with a number of diseases, including cancer, diabetes, cardiovascular disease, low immunity, multiple sclerosis, and rheumatoid arthritis. Studies have shown that adequate Vitamin D levels in the blood may prevent breast, colon and prostate cancer, Dr. Eid said.

While the Recommended Daily Allowance of Vitamin D is 400 IUs (International Units), researchers feel that may be inadequate to maintain the body's necessary level of Vitamin D, said Joanne Shearer, registered dietitian with the Avera Heart Hospital of South Dakota in Sioux Falls. Vitamin D is found naturally in a few foods such as salmon and egg yolks. Milk is fortified with Vitamin D - providing 100 IUs per serving. "Even with fortification, it's almost impossible to get enough Vitamin D from our food," Shearer said. "Yet all the cells of our bodies need Vitamin D to function properly."

Sun is nature's best source of Vitamin D, although there's a balance between over-exposure to the sun, and getting enough sun to boost Vitamin D levels. Safe sun exposure of five to 10 minutes a day, three times a week can generate 10,000 to 20,000 IUs of Vitamin D. Because the human body stores Vitamin D, our bodies are designed to "fill up the tank" in the summer, and draw on those reserves in the winter, Shearer said.

Certain people are more prone to Vitamin D, including African Americans and Hispanics, or people who are overweight, have liver or kidney disease, or who have had gastric bypass surgery.

A simple blood test at your doctor's office can determine your Vitamin D levels. Winter is the best time to be checked, Dr. Eid said. If your level is low, your doctor will probably prescribe supplements, depending on how low the level is. A good maintenance dose is 800-1,000 IUs a day, although this could be too low for people who already have a deficiency. It's wise to get checked before taking a supplement, because too much Vitamin D can be toxic, Dr. Eid added.

Linda Roberts of Sioux Falls started taking Vitamin D supplements after a blood test last February revealed she was very deficient. Her Vitamin D measured 13 ng/mL, compared to an optimal level of 50-60 ng/mL.

"I don't get a lot of sun, working inside and living in this climate," Linda said. When she first heard the symptoms of Vitamin D deficiency, they seemed to match up with how she felt. "I was always tired and sluggish, without a lot of get up and go."

Within two to three weeks after beginning to take supplements, Linda noticed a huge difference. "I started feeling so much better - sharper and like I didn't need to sleep all the time. It woke me up to the fact that our bodies really need Vitamin D."

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