During the peak summer months, most healthy individuals can produce all the vitamin D they need by exposing the skin on their face, arms, and legs to sunshine for just a few minutes each day. Experts recommend seeking out sunlight during the middle of the day—between 10 a.m. and 4 p.m.—when the sun is highest in the sky and the UVB rays are strongest.
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However, as summer winds down into autumn and winter—especially in locations farther from the equator—UVB rays tend to be weaker and therefore less impactful. As a result, you may be more vulnerable to developing a vitamin D deficiency, a condition that can affect your bone health, trigger a calcium imbalance in your blood, and cause muscle weakness, cramps, fatigue, respiratory problems, and more.
Brynna Connor, MD, a board-certified family medicine physician specializing in anti-aging and regenerative medicine and the Healthcare Ambassador for NorthWestPharmacy.com, says vitamin D deficiency can have far-reaching effects on health. In severe cases, it can cause osteoporosis in adults or rickets in children.
“Vitamin D helps your body absorb calcium more efficiently,” Connor says, noting that only 15 to 20 percent of the calcium you ingest through eating and drinking is absorbed by the body. “When vitamin D becomes activated, it forms the hormone calcitriol that interacts with cells in the kidneys and intestines, triggering the organs to absorb more calcium.”
Since your natural absorption will vary depending on the sun’s intensity, you can plan your intake depending on the season. Endocrinologist John Bilezikian, MD, wrote on behalf of Columbia University Irving Medical Center that if you live in New York, for example, you should assume that the sun will provide “minimal or no vitamin D” between the months of October and April, regardless of how much time you spend outdoors. “This is when supplements are vital,” he says.
Between May and September, Bilezikian says that getting between 15 to 20 minutes of sun exposure per day is enough. If you’re planning to be in the sun for longer stretches of time, it’s important to apply a high-SPF sunscreen to minimize your risk of sun damage and skin cancer.
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The experts add that seniors over the age of 70 may need more time in direct sunlight since our skin becomes less efficient in producing vitamin D over time.
“Older adults who suffer from a vitamin D deficiency may also be more prone to falls, which, coupled with decreased calcium levels and weaker bones, can lead to increased incidents of fractures or breaks,” Connor warns.
Eating a diet that’s rich in vitamin D, including foods such as fatty or oily fish, egg yolks, mushrooms, and milk and dairy products, can also help to safely raise your levels. However, seeking out safe sun exposure and taking a daily vitamin D supplement are still considered the most effective ways to increase your vitamin D stores. According to the National Institutes of Health (NIH), most adults should aim to get 15 micrograms (mcg) or 600 international units (IU) of vitamin D. People in their 70’s or older should get 20 mcg/800 IU to protect against osteoporosis.
Of course, if you suspect you may have a vitamin D deficiency, your medical provider can confirm this with a blood test and help you determine the best solution for your unique medical circumstances.
“As with any supplement, you should talk to your doctor before starting a new course of treatment to ensure there is no risk of adverse events,” Connor advises.
