Vitamin D – The Sunshine Vitamin

  • April 15, 2019
Vitamin D | LTA

Written by Lesley Herrmann, MSc., CNC

If you’re starting to feel a little gloomy it may be time to check your vitamin D levels. Vitamin D is known as the sunshine vitamin because our bodies can synthesize it through a reaction that occurs when UVB rays interact with our skin. When sunlight strikes the skin, it converts the precursor 7-dehydrocholesterol into vitamin D3 or cholecalciferol. This molecule then gets transported to the liver and then to the kidneys before ending up as 1,25-dihydroxycholecalciferol, which is ten times more potent than cholecalciferol and the most potent form of vitamin D3 in our body1.

Signs of low vitamin D levels include depression, seasonal affective disorder, and other cognitive symptoms, so it makes sense that one may start feeling gloomy during long cloudy winters. The research found that 85% of adults in America were deficient in vitamin D, and the lowest levels were measured in the late winter months2. A nice warming sunbathe might be just what we need! Who’s ready for the beach?

Your daily dose of healthy sunlight can improve Vitamin D levels

Although it is common practice to avoid the sun by lathering on sunscreen, some exposure to UVB rays is actually beneficial to our health and can help prevent some skin cancers, like melanoma2. UVA rays, on the other hand, can increase the risk of skin cancer. The best way to get your daily dose of sunlight is to spend 10-40 minutes in direct sun between 10 AM and 2 PM2. The best time to catch UVB rays is at solar noon (during daylight savings time, solar noon is closer to 1 PM). However, we can’t make vitamin D all year long; UVB rays only reach Earth’s surface from about April 1st to October 1st,3. You’ll need to expose large areas of skin such as your back, arms, legs, and or belly, and be sure to avoid lotions and oils to allow for maximum absorption. Exposing only your hands, feet, and face won’t be enough skin area. In fact, it’s best to keep your face covered to prevent aging and wrinkles, since areas on our face are quite delicate.

The daily recommended sun exposure varies depending on your skin tone. If you have very fair skin, 10-20 minutes is likely all you need, but those with darker skin will need a bit more time. After your sunbath, it is best to wait a few hours before showering to avoid washing away some of the beneficial chemical reactions.

If you plan to spend a lot of time in the sun, it is still important to protect your skin from over-exposure, as reoccurring sunburns increase your risk of skin cancer. So, it’s a good idea to apply sunscreen or wear lightweight clothing. Check out the Environmental Working Group’s resource Guide to Sunscreens for safe products. Wearing a wide-brimmed hat or baseball hat is also beneficial.  

Other roles of Vitamin D

In addition to lightening our mood, vitamin D is also very important for supporting the immune system. It helps to modulate the innate and adaptive immune response, making it important for preventing and managing autoimmune conditions. It also exhibits infection-fighting abilities, helping the body overcome colds and the flu, and helps lower the risk of certain cancers, including pancreatic, lung, ovarian, and prostate cancer. Vitamin D plays a significant role in regulating calcium and phosphorus absorption in the intestines, aids in the regulation of calcium balance, and stimulates bone cell mineralization. Low vitamin D levels can increase the risk of osteomalacia and bone fractures.


It’s a good idea to get your vitamin D levels checked before and during supplementation. The 25-hydroxyvitamin D, or 25(OH)D, is the best test to use because it is the better marker for overall D status.

For healthy individuals with a strong immune system, optimal vitamin D levels range between 50 and 70 ng/mL, based on functional medicine practice. For those treating cancer, heart disease, and autoimmune conditions, levels of 70-100 ng/mL are recommended2.

Below are the dose recommendations for different age groups:

  • Children 5 and under: 35 units per pound
  • Children 5-10: 2500 IU/day
  • Adults: 5000 IU/day
  • Pregnant women: 8000 IU/day

The only way to know what dosage is right for you is to get your levels tested! It is important that blood levels not exceed the upper limit of 100 ng/mL, so remember to test your levels before and during supplementation.

The best form for supplementation is D3, which is nearly 90% more effective than D2 (2). Unfortunately, it is the form D2 that is commonly found in fortified foods, such as milk and milk alternatives. Vitamin D3 should always be supplemented with vitamin K2 to avoid vitamin D toxicity symptoms, which includes calcification of the arteries. Vitamin K2 helps direct calcium into the areas where it is needed, like the bones and teeth.

Because of the many important functions of vitamin D, and because the rate of deficiency is so high in the U.S., it’s a good idea to check your vitamin D levels regularly for optimal health.

Written by Lesley Herrmann – http://www.awakenedtaste.com/

You can find high-quality D3 and K2 nutraceuticals at FullScript, an online source for practitioner-grade supplements. My favorite trusted brands include Designs for Health, Pure Encapsulations, or Pharmax. Sign up today and receive 10% off all products!

Murry et al (2005). The Encyclopedia of Healing Foods. Atria Books, New York, NY. Pages 100, 103-104.

  1. Mercola, J. (1997-2019). Vitamin D Resource Page. Available at https://www.mercola.com/article/vitamin-d-resources.htm
  2. USNO (2015). Sun or Moon Altitude/Azimuth Table. United States Naval Observatory. Available at https://aa.usno.navy.mil/data/docs/AltAz.php
  3. Mayo Clinic (1998-2019).  Osteomalacia: Symptoms and Causes. Available at https://www.mayoclinic.org/diseases-conditions/osteomalacia/symptoms-causes/syc-20355514