The End of Daylight Savings Means More Vitamin D

Sunday, November 3rd marks the end of daylight savings in America and the beginning of longer, darker days. While this may prove glorious for bats and other furry creatures of the night, fewer hours of sunlight can lead to serious health consequences for humans including those that stem from vitamin D deficiency.

According to the American Journal of Clinical Nutrition, vitamin D deficiency is now recognized as a pandemic; its primary cause – lack of exposure to sunlight.1 It’s true; most vertebrates rely on exposure to sunlight for their bodies to produce sufficient amounts of vitamin D. It’s also true that during winter, there is a higher prevalence of vitamin D deficiency across North America.1

The Health Role of Vitamin D

The primary function of vitamin D is to help our bodies maintain normal blood levels of calcium and phosphorus. By aiding in the absorption of calcium, vitamin D helps our bodies form and maintain strong, healthy bones.2 Vitamin D also plays an important role in heart, lung, brain and muscle function.1

The Health Consequences of Vitamin D Deficiency

To date, there are a number of health conditions that are linked to vitamin D deficiency, including osteopenia, osteoporosis, rickets in children and fractures in adults. Low levels of vitamin D are also associated with common cancers, autoimmune diseases, hypertension, and infectious diseases.1 Researchers are beginning to discover that, because vitamin D deficiency may also increase the severity of some diseases, vitamin D supplementation is an important part of disease management.3

Groups at Risk for Vitamin D Deficiency

For many people, eating foods naturally rich in, and fortified with, vitamin D and being exposed to a moderate amount of sunlight is enough to maintain adequate vitamin D levels.4 Some groups of people however, are at higher risk of vitamin D deficiency than others. Talk to your healthcare provider about getting a blood test to check your vitamin D levels if you identify with any of the following:4

  • Your exposure to sunlight is limited.
  • You have naturally dark skin.
  • You are obese.
  • You are elderly.
  • You have a medical condition, like inflammatory bowel disease, that affects the absorption of nutrients.

How Much Sunlight Do You Need?

First we’re told to stay out of the sun because too much of it causes skin cancer. Now we’re told that too little sun can cause vitamin D deficiency that can lead to serious health conditions. Indeed, there is a Catch 22 when it comes to sun exposure and our health. So, what level of sun exposure is considered safe?

The American Journal of Clinical Nutrition reports that people can generally obtain ample vitamin D levels from a combination of diet, supplements, and incidental protected sun exposure.5 This type of sun exposure can be obtained on a daily basis by simply walking around the block or mowing the lawn while wearing sunscreen with an SPF of at least 15 to thirty.

Dietary Sources of Vitamin D

Unfortunately, unless it’s been added, there are few food sources that are rich in vitamin D. Thankfully, your body generally produces enough vitamin D from exposure to sunlight. During winter, or any time of year when sunlight exposure is limited however, consider eating a variety of foods that are naturally packed with vitamin D. These include:6

  • Salmon, preferably wild-caught
  • Mackerel, preferably wild-caught
  • Cod-liver oil
  • Canned tuna
  • Canned sardines
  • Beef or calf liver
  • Egg yolks
  • Cheese
  • Milk, yogurt, breakfast cereals and orange juice fortified with vitamin D

Supplementing Your Diet with Vitamin D

Since 2000, there has been a lot of controversy over the benefits of vitamin D supplementation and how much is sufficient. The current, recommended daily allowance (RDA) for vitamin D is based on age and is as follows:4

  • 0-12 months – 400 IU daily
  • 1 – 70 years of age – 600 IU daily
  • 71 years and older – 800 IU daily
  • Pregnant and lactating women – 600 IU daily

Higher doses of vitamin D, as recommended by your doctor, may be necessary to correct deficiencies (especially in winter) and for post-menopausal women.

Please note:  As a supplement, taking too much vitamin D can lead to serious health consequences. Before purchasing a vitamin D supplement, talk to your healthcare provider about which dose of vitamin D is right for your specific health condition.


Author: Deborah Leader RN, BSN, PHN


1 Michael F. Holick and Tai C Chen. Vitamin D deficiency: a worldwide problem with health consequences. Am J Clin Nutr April 2008 vol. 87 no. 4 1080S-1086S.
2 The Mayo Clinic. Vitamin D. Updated July 13, 2013.
3 Vitamin D Council.What is the Vitamin D Council?
4 Office of Dietary Supplements. Dietary Supplement Fact Sheet: Vitamin  D. The National Institutes of Health. Reviewed June 24, 2011.
5 Barbara A Gilchrest. Sun exposure and vitamin D sufficiency. Am J Clin Nutr August 2008 vol. 88 no. 2 570S-577S.
6 WebMD. The Truth about Vitamin D: Vitamin D Food Sources. December 17, 2009.

Leave a Reply

Your email address will not be published. Required fields are marked *

HTML is not allowed in comments. It is automatically filtered out of comments.