Vitamin D, Sun Block, Sunlight, and Cancer

by Kate Dee, MD

Vitamin D is critical for your health. Most people do not get enough sunlight to make a healthy amount of Vitamin D, and on top of that we are also told to wear sunblock to prevent skin cancer and aging! What should we be doing, exactly?

What does Vitamin D do?

● Regulates the levels of calcium and phosphate in the bloodstream
● Promotes the mineralization and growth of bones
● Critical role in the immune response, allowing the killer T-cells to defend against infections
● Modulates the expression of genes that regulate cell proliferation, apoptosis, and differentiation, playing an important role in cancer incidence. Epidemiology suggests links between vitamin D deficiency and most cancers, including breast and colon cancer
● Reduces systemic chronic inflammation.

Getting Vitamin D from the Sun

The amount of sun needed for adequate Vitamin D production by your body depends on how much melanin you have. Light-skinned humans need about 20 minutes of unfiltered sunlight over large portions of their bodies to get enough Vitamin D on a daily basis. The darker your skin, the more sun exposure you require, up to 2 hours for very dark skin. Very few Americans get this kind of sun on a daily basis, and as we know, the sun also contributes to aging and, alas, skin cancer. For Vitamin D, you absolutely do not need more than this. If your skin is red, you’ve had too much, and any excess will contribute to a burn or tan, but will also contribute to aging and cancer. Most people in the world do not get enough sun to provide adequate Vitamin D.

Foods with Vitamin D

There is a lot of Vitamin D in wild salmon, mackerel, herring, catfish, cod liver oil, beef liver, cheese and eggs. Unfortunately, it takes large volumes of these items in our diet to supply enough Vitamin D for your health. So, eat them with abandon, but you’ll have to take some additional supplements.

Vitamin D supplements

How much Vitamin D do you need to eat to get enough Vitamin D? A good general rule is 4000 IU per day. Ideally, get a blood test for Vitamin D before you start supplements, take 4000 IU supplements daily, and get them tested again after two months. Ideally, your levels should be above 50 ng/mL. If you don’t see enough of a bump with 4000 IU, feel free to increase the dosage. Given that we can make around 10,000 IU in well under an hour of sun exposure, supplementation up to that level is well tolerated. Remember the supplement industry is NOT regulated. Make sure you’re using a brand that independently tests their products for purity and potency.

How much Sun Block?

For anti-aging, make sure you use sun block every day on any part of your skin that you care about what it looks like. For most people, that’s your face, neck and décolleté. You might want to add your hands, as we get lots of inquiries from older patients about how to remove age spots from the hands. The UV A rays from the sun do not cause burns, but they do cause all the same aging, sun damage, age spots and cancer that UV B rays do. And UV A rays travel right through the clouds and the rain, right through the windows, and land on your skin all winter, even indoors. So wear a high quality sun block on those parts every day of the year.

For anti-cancer-- wear sun block on all sun exposed areas of your skin if you are going to have more than 20 minutes of unfiltered sun exposure if you have light skin and up to 2 hours if your skin is darker. If you get a sunburn, it was too much. If you don’t tend to burn but get tan, that is still way more than you need to generate daily Vitamin D requirements, and all the extra UV rays will make you appear old before your time (think Magda in Something About Mary) and increase your risk of skin cancer.

If you need to find a great sunblock, we have multiple options depending on whether you like your product to be moisturizing, physical, water-resistant, dewy or mat, face or body. We try to get all of our patients into a sun block they just love the feel of on their face, so they’ll use it every day. We love the EltaMD family of sun block-- there is something for everyone!

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