Darker Days Mean Less D.
Darker days may be bad for your health. Less sun means less vitamin D production. Our major source of vitamin D is from the sun reacting with our skin, so dark days mean less vitamin D. There are very few food sources of this vital vitamin so without the sun, your daily dose may be low. You need at least 10 to 15 minutes of sun two to three days a week to make enough D. But there are some problems with depending on the sun for your D.

  • You need direct rays to make vitamin D. You may feel the warmth of the sun but it doesn't mean that you're making vitamin D. The sun needs to hit your skin at a direct angle for the best vitamin D production. The hours between 10:00 and 3:00 on a sunny day are best for vitamin D boosting.
  • Darker Skin Makes Less D. African-Americans and other groups with darker skin make less D. The melanin that gives darker skin its tone acts as a natural sunscreen and blocks vitamin D production.
  • Older Skin Make Less D. Our skin thins as we age. Thin skin has less of the chemical that the sun turns into vitamin D.
  • Sunscreen Blocks Vitamin D Production. An SPF as low as a 6 can vastly lower vitamin D production.

So even during the sunny summer months, you may not be making enough D. Vitamin D does so many great things for our bodies - including calcium absorption, muscle strengthening and possibly cancer prevention - that we can't afford to miss out. You need to get 1000 to 2000 IU's (international units) of vitamin D every day. So how are you going to get it if food and sun can't cut it?

Here's the best way to boost vitamin D:

  • Take a Multivitamin. Most multivitamins contain 400 IU's of vitamin D.
  • Buy Calcium Supplements with D. Most calcium supplements have D added.
  • Drink milk and D-added Juice. Milk and some orange juices are fortified with vitamin. One cup of each contains 100 IU's of vitamin D.
  • Add a D Supplement. This type of vitamin D is stronger and better than its cousin, Ergocalciferol (D2). If you're not getting enough from your multi & calcium supplements, then adding in a separate vitamin D supplement can certainly help.

If you're surprised that we've not focused on food in this segment, it's because there are very few high vitamin D foods. So, look to your vitamin D fortified foods and dietary supplements to give you your daily dose of D. 

Beth Kitchin PhD RD
Assistant Professor, UAB Department of Nutrition Sciences