Do you get vitamin d through windows

Ten minutes or so of sun exposure to your face and arms is roughly equivalent to 200 IU of vitamin D supplement

Dear Dr. Roach: Does our skin make vitamin D from sun exposure through a car’s windshield? Sometimes I expose my stomach for about 10 minutes while driving or riding in a car, but I’m not sure if the skin responds the same way through glass as it does with direct sun exposure.

S.R.

Sunlight allows our skin to convert 7-dehydrocholesterol (made from cholesterol) to previtamin D3, which then becomes vitamin D3, the active form. The type of sunlight that is effective for this is in the ultraviolet spectrum, called UV-B. UV-B is effectively filtered out by windshields and ordinary glass, so you are NOT able to get vitamin D through the window: You need to go out into the sun. Ten minutes or so of exposure to your face and arms is roughly equivalent to 200 IU of vitamin D supplement. The exact amount depends on your skin type (lighter skin is much more efficient at using sunlight to convert vitamin D), your latitude, the season and the time of day.

UV-A light can get through most windows and light cloud cover, but not through UV-blocking window films that you can buy to block UV for your home and car windows. It does not help you make vitamin D. Unfortunately, it does penetrate deep into the skin, prematurely aging the skin and predisposing you to cancer. So, I wouldn’t recommend exposing your skin through a windshield, as it won’t cause health benefits and could cause health harms.

Dear Dr. Roach: I had my annual flu shot a week ago. I am eligible for the Pfizer booster shot now. How long should I wait to get the booster shot? I am 82 years old, and my second COVID-19 shot was in mid-March.

M.R.

Back in March, when you got the initial two doses, the Centers for Disease Control and Prevention and others recommended against getting any kind of vaccine within two weeks of getting the COVID-19 vaccine. That recommendation has been removed, and you can get the flu vaccine on the same day of your COVID-19 booster if you wish.

I do recommend the flu shot, which is available for all ages over 6 months. Last year, there was hardly any flu, because of the mask-wearing and social distancing protocols in place. These are still in place in many locations, so it’s possible we could have another light flu season. However, they are NOT in place in others, and because children are back at school in most parts of the North America, there is likely to be a lot more flu than last year. Further, because essentially nobody got the flu last year, there is much lower resistance in the population than normal, so experts are worried about a severe flu season.

The flu makes you feel terrible, and with COVID-19 still out there, a person with the flu might legitimately worry about having COVID, necessitating quarantine and testing. It’s far better to avoid this if you can by getting the flu shot and the COVID-19 booster if you meet the guidelines. It is certainly true that the flu vaccine isn’t perfect, but it remains the best way to prevent flu.

Dr. Roach regrets that he is unable to answer individual letters, but will incorporate them in the column whenever possible. Readers may email questions to [email protected]

Medically reviewed by Rosanna Sutherby, PharmD on May 15, 2020. Written by Libby Pellegrini. To give you technically accurate, evidence-based information, content published on the Everlywell blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

To boost your vitamin D levels, your best bet is to go out and get some sun exposure—instead of just turning to your diet (since most foods don’t naturally have vitamin D).

That also means that if you’re not regularly getting very much sun exposure, you could very well be vitamin D deficient (which you can detect with an at-home vitamin D blood test).

If so, you aren’t alone: researchers estimate that about 40% of adults in the United States are vitamin D deficient, which can lead to symptoms like fatigue, depression, and joint pain.

This “sunshine vitamin” assists the body and the immune system in a number of different ways. Vitamin D helps regulate the amounts of calcium and phosphate within the body. Calcium absorption can actually increase with adequate vitamin D.

People with a low vitamin D status may experience vitamin D deficiency signs like issues regarding their muscle, teeth, and bone health if left untreated. Not only that, but vitamin D insufficiency can sometimes lead to rickets in children or can cause mood swings in some individuals. So it’s essential to have a sufficient amount of vitamin D because it plays such an important role in the body.

Not sure how to get vitamin D from the sun? Below are our top vitamin D and sunlight tips to help you get more of this vital nutrient.

Tip #1: It’s a good idea to check your vitamin D levels in the winter to make sure your levels don’t get too low.

Here’s Why: Less sunlight (and less UVB rays) reaches the surface of the Earth—and your skin—during winter. (That’s due to the fact that the Earth is tilted on its rotational axis.) And with less sunlight comes less vitamin D production in your body. That's why it can be a good idea to take a vitamin D supplement during the winter.

Tip #2: To actually take advantage of the sun’s vitamin D-producing effect, spend good time outdoors – instead of only getting sunlight exposure while in a car, office, or in your home. Increasing your exposure to the sun by spending just an extra 10-15 minutes outdoors can be beneficial for your vitamin D level.

Here’s Why: Can you get vitamin D through a window when sunlight streams in? The answer, in general, is “no.” It might seem like glass lets all the sun’s UV rays get through to you, but that’s just an illusion: glass – as well as plexiglass and plastic – absorbs all UVB radiation. Thus, even if sunlight is streaming through the windows of your car or home, your body won’t produce any vitamin D in response.

Tip #3: Check the amount of air pollution in your city by visiting AirNow.gov.

Here’s Why: Did you know that the amount of pollution in your environment can influence how much of this “sunlight vitamin” your body produces? Air pollution – the byproduct of massive amounts of traffic and more – absorbs UVB rays from the sun, leaving less of it to be absorbed by your own skin. So even though cities like Los Angeles and San Diego – for example – get lots of sunlight year round, there’s nevertheless a relatively high risk of a vitamin D deficiency in these cities because of fairly high levels of air pollution.

Tip #4: If you have a low vitamin D level, your altitude could be a contributing factor.

Here’s Why: Imagine you live at the top of a tall mountain, where the air is crisp and thin. In this scenario, chances are you’re getting a lot more direct sunlight than someone living in a deep valley. The reason why? At higher altitudes, the atmosphere is thinner – so sunlight isn’t blocked out as much. So you face a higher risk of vitamin D deficiency the lower your altitude.

Tip #5: If you tend to wear sun protection (a sunscreen) whenever you step outside, and you’re really good at using it to cover up all areas of your skin that sunlight lands on, then allow yourself 10 minutes of sunlight exposure a few times a week – without any sun protection on.

Here’s Why: Most people don’t apply sunscreen in a way that completely blocks out UV radiation. However, if you’re very effective at using sunscreen to cover up all parts of your body that would be exposed to sunlight, then you’re at a higher risk of vitamin D deficiency (assuming you wear sunscreen just about any time you go outdoors).

This is because sunscreen formulas generally block out the sun’s UV rays. For example, a sunscreen with SPF 30 will absorb up to 98% of the UVB rays from the sun.

Tip #6: The darker your skin color is, the greater your risk of having a deficiency of the “sunshine vitamin” – making it especially critical that you monitor your vitamin D levels.

Here’s Why: Skin color is largely determined by melanin, a natural pigment that acts as a sunscreen. In short, melanin absorbs UVB rays before they can reach deeper into your skin and trigger vitamin D production. If you have dark skin, then you have more melanin – which can put you at risk of vitamin D deficiency, particularly if you don’t spend much time outside in the sun.

Don't know if your vitamin D level is high enough? Easily check your vitamin D status from the comfort of home with our convenient at-home vitamin D test kit.

References

1. Parva NR, Tadepalli S, Singh P, et al. Prevalence of Vitamin D Deficiency and Associated Risk Factors in the US Population (2011-2012). Cureus. 2018;10(6):e2741. doi:10.7759/cureus.2741

2. Wacker M, Holick MF. Sunlight and Vitamin D: A global perspective for health. Dermatoendocrinol. 2013;5(1):51-108. doi:10.4161/derm.24494

3. Thacher TD, Clarke BL. Vitamin D insufficiency. Mayo Clin Proc. 2011;86(1):50-60. doi:10.4065/mcp.2010.0567