When the weather cools down, your urge to curl up inside until spring might ramp up. And while cozy days indoors might sometimes be a truly sublime pleasure, an unexpected complication may arise in regions with cold and gray winters: vitamin D deficiency.
Also called the sunshine vitamin, vitamin D is synthesized in the skin after exposure to ultraviolet B rays and is essential for calcium absorption and maintaining strong bones. Vitamin D deficiency can lead to weaker bones and is associated with a number of adverse effects including increased inflammation, increased risk of autoimmune disease, and decreased cognitive function. During the summer, most healthy people can produce sufficient vitamin D through a modest amount of sun exposure — five to 10 minutes at midday for several days each week for people with fair skin, and longer periods for people with darker skin.
In much of the U.S., however, winter sunlight is too weak to spur vitamin D synthesis, which can lead to deficiencies. According to Nebraska Medicine, nearly 1 in 4 U.S. adults are low in vitamin D, and the condition has become more common in recent years. Symptoms may include fatigue, poor sleep, bone pain, feeling depressed or sad, hair loss, muscle weakness, loss of appetite, frequent illness, and paler skin. If you notice these symptoms, contact your doctor — they can measure your vitamin D levels with a simple blood test.
Fortunately, vitamin D deficiency is easily remedied with appropriate foods and vitamin supplements. Certain fish (like salmon and sardines) are naturally high in vitamin D, as well as egg yolks and beef liver. Many other foods, like milk and breakfast cereals, are enriched with additional vitamin D.
Vitamin D supplements come in two forms, D2 and D3. Several studies have shown that D3 raises vitamin D levels more effectively, and many physicians recommend it for this reason. For young adults, the recommended dietary allowance of vitamin D is 600 international units. Your physician can recommend an appropriate dosage for you.
