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Vitamin D deficiency is surprisingly common, even in warm sunny climates. Health experts often call it “the silent epidemic” because so many people unknowingly suffer from a lack of vitamin D. Yet a deficiency in vitamin D can have huge consequences for your health.
It’s easy to assume that we’re getting enough vitamin D from the sun exposure we get from day-to-day activities and our commute to work. But this couldn’t be further from the truth.
In fact, studies have shown that around 41% of Americans and Europeans are deficient in vitamin D. And these rates are significantly higher (up to 80%) for those who have darker skin. That’s because darker skin is less efficient at converting the sun’s rays into vitamin D.
When you have a vitamin D deficiency, it’s easy to be unaware of it because the symptoms are vague, and are easily dismissed as “normal” including:
Vitamin D deficiencies often go unrecognized because we assume the symptoms are caused by a lack of sleep, working too hard, stress, or old age.
The long-term effects of a vitamin D deficiency are even more reason to ensure you get enough on a daily basis. For example, a study published in Anticancer Research reported that breast cancer patients with high levels of vitamin D were twice as likely to survive their cancer, compared to women with lower levels.
Over time, vitamin D deficiency can lead to:
For the body to produce vitamin D from sun exposure, the sun’s rays need to directly hit your skin.
That’s why people who live in northern latitudes can’t make any vitamin D in winter—the angle of the sun is such that no vitamin D is produced.
And if you’re counting on your commute or sunny office to make vitamin D, you may be setting yourself up for premature aging instead.
That’s because glass blocks ultraviolet B (UBV) radiation, the part of the sun’s rays that stimulate vitamin D production. However, glass allows UVA radiation to pass through, which can damage the skin.
To make vitamin D you need to be outside, ideally when the sun is directly overhead (for greater UVB exposure), with direct sun-to-skin exposure on the arms, legs or torso.
When it comes to the amount of sunlight needed to make optimal levels of vitamin D, it takes a goldilocks approach: not too much, and not too little. It has to be just right.
Fairer skin requires less time in the sun than darker skin. Those living in northern latitudes need more time to make vitamin D, even in summer.
Still, most people need around 15 to 20 minutes of direct sun (in summer) to make vitamin D. Too much sun and there are no added benefits. Your body can only produce a limited amount of vitamin D a day.
One study, published in the journal Science of the Total Environment, evaluated the amount of time needed to make 1,000 IUs of vitamin D in Spain, a country with a warm, sunny climate.
The researchers found that in summer, a person could make 1,000 IUs with 10 minutes of midday sun, providing that 25% of the body’s skin was exposed and no sunscreen was used. However, they could not spend more than 29 minutes outside without risking sunburn (and inflammation).
Because people spend most daylight time indoors, and wear full clothing or sunscreen when outside, it becomes easy to see why so many people are vitamin D deficient.
That’s why supplementing with vitamin D is a smart move. With regular intake of vitamin D, you take the guesswork out of the season, climate, skin type and time of day to make vitamin D.
Depending on your lifestyle and where you live, supplementing with vitamin D may be the best way to ensure you’re getting enough.
But there’s a catch with vitamin D supplements… you must be sure your body can absorb vitamin D. Here are three ways to enhance absorption.
While the Recommended Daily Allowance (RDA) for vitamin D is 400 IUs a day for adults, many health experts consider this to be too low to meaningfully impact your vitamin D levels. For optimal vitamin D, seek out a supplement with 1000 to 2000 IUs a day.