Vitamin D for Daylight Savings

By Ashley Reaver, MS, RD, CSSD, April 14, 2021


With Daylight Savings Time beginning, this week brings the promise of longer days and more sunshine. But don’t be fooled into thinking the return of the sun means you can toss your vitamin D supplement out the sunroof. Maintaining optimal levels of vitamin D throughout the year and following a few simple steps will help to make sure you don’t leave your vitamin D in the shadows.

What’s sun got to do with vitamin D?

Commonly called the sunshine vitamin, vitamin D is produced naturally in the skin when it is exposed to ultra-violet (UV) rays from the sun, specifically UVB rays. UVB rays react with a form of cholesterol found in the skin called 7-dehydrocholesterol. It is ultimately converted to vitamin D3. Unfortunately, the sun is not always a consistent source for vitamin D production.1

Try getting vitamin D through food instead. Download 10 recipes packed with vitamin D now!

Throughout the winter months, the Northern Hemisphere of the Earth, and the United States, are tilted away from the sun. This tilt increases the distance of the U.S. from the sun and causes the UVB rays to be much weaker. This effect is most pronounced for anyone living above Maryland. Essentially, anyone living in those states is not naturally producing vitamin D in the skin from approximately November to April. 1

However, even when the Northern Hemisphere tilts back towards the sun throughout the Summer, we are still at risk for low levels of vitamin D. The biggest culprit is fear of the sun, and for good reason. Due to skin cancer awareness growing dramatically in the past few decades, long gone are the days of baby oil and aluminum foil reflectors. In fact, many people, especially the elderly and children, are severely limiting their skin exposure to the sun.

Infographic - Vitamin D (1)

Blocking sunlight may block vitamin D production

There are several physical barriers setting us up for vitamin D deficiency even during the summer months:

  1. Wearing hats, long sleeves, and pants
  2. Sitting in shaded areas, such as under a tree or umbrella
  3. Working indoors during peak sun hours
  4. Constant sunscreen usage

While these all play a role, sunscreen application is most likely the leading contributor to sunshine deficiency. Did you know that SPF 15 sunscreen blocks 98% of UVB rays?1 That is basically blocking the possibility of any vitamin D production at all! While we definitely aren’t advocating hours of sunbathing on the beach, allowing your skin to be kissed by the sun each day for just 20 minutes without clothing or sunscreen can help you maintain your vitamin D levels. Have a darker skin tone? You likely require longer exposure to the sun to meet your requirements. The increased melanin, what causes the change in pigmentation of the skin, reduces the amount of vitamin D produced.1

Besides sunlight, here are other ways to get vitamin D

There are some foods that will also help you maintain your vitamin D levels. 2

  1. Fortified dairy and dairy alternatives can be consumed at least once per day
  2. Fatty fish such as halibut, mackerel, eel, salmon, swordfish and trout are excellent sources of vitamin D and should be consumed at least twice per week (see above!)
  3. And of course, there are vitamin D supplements for when sunshine just isn’t enough.


When is sunshine not enough?

Even sunshine and proper nutrition typically do not provide enough vitamin D to lift an individual from the depths of deficiency. They are good, however, for helping to maintain levels—especially in the summer months when production from the sun also contributes. However, individuals that are clinically deficient in vitamin D should supplement with vitamin D3 in order to increase their levels of vitamin D.

How do you know if you require a vitamin D supplement? Or what is the appropriate dosage for you? Well, get your vitamin D levels tested. Don’t assume you are okay! Surprisingly, less than 15% of InsideTracker users fall into our optimal range! This includes individuals living in Florida year round with abundant sunshine and professional baseball players that spend large amounts of time outside in the sun.

D3_Testosterone_-1.jpgVitamin D was once believed to only play a role in calcium absorption and bone health, and it certainly does. In fact, it plays a role in the absorption of several key minerals: calcium, iron, magnesium and zinc. A vitamin D deficiency could result in inadequate calcium deposition in bone leading to rickets in children and osteoporosis in the elderly.

Aside from bone health, vitamin D also plays an integral role in tons of other bodily processes. The development and maintenance of the nervous system requires vitamin D, and a lack of adequate vitamin D is associated with a greater incidence of depression and irritability. Skeletal muscle formation and upkeep also requires vitamin D. Low levels of vitamin D are correlated with muscle weakness, slower reaction times and impaired coordination.4 Testosterone, weight maintenance, sleep quality, and inflammation are all connected to adequate vitamin D levels.

Here's your winning strategy on how to optimize your vitamin D levels all year long

  1. Get 20 minutes of untainted sunshine on your skin each day
  2. Back up your skin production by consuming fortified dairy or dairy alternatives and fatty fish
  3. Get your vitamin D levels tested and, If necessary, take a supplement
  4. Monitor your levels and make adjustments to your plan throughout the year



  1. AC Ross, CL Taylor, AL Yaktine, et al. Dietary Reference Intakes for Calcium and Vitamin D. Institute of Medicine (US) Committee to Review Dietary Reference Intakes for Vitamin D and Calcium. 2011
  1. Lips P, van Schoor NM, de Jongh RT. Vitamin D status and nutrition in Europe and Asia. Journal of Steroid Biochemistry and Molecular Biology. 2007;103(3–5):620–625.
  1. Tripkovic L, Lambert H, Hart K, Smith CP, Bucca G, Penson S, Chope G, Hyppönen E, Berry J, Vieth R, et al. Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis. American Journal of Clinical Nutrition 2012;95:1357–65.
  1. De konig EJ, van Schoor NM, Penninx BW, Elders PJ, Heijboer AC, Smit JH, Bet PM, van Tulder MW, den Heijer M, van Marwijk HW, Lips P. Vitamin D supplementation to prevent depression and poor physical function in older adults: study protocol of the D-Vitaal study, a randomized placebo-controlled clinical trial. BMC Geriatrics. 2015 Nov 19; 15:151.


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