As many as 70% of American teens and adults are thought to be deficient in vitamin D-often called the sunshine vitamin-since it is difficult to get from diet alone and most people are limiting their unprotected sun exposure. Research over the past 10 years has demonstrated vitamin D's critical role in overall health, making these deficiencies a matter of increasing concern.
The National Institutes of Health states that vitamin D is not only essential for bone health, but also for the modulation of neuromuscular and immune function and reduction of inflammation. Strong biological evidence also indicates that vitamin D works to prevent colon, prostate, and breast cancers.
In 2007, a group of leading nutritionists stated that "public health is best served by a recommendation of higher daily intakes of vitamin D" in an editorial submission to the American Journal of Clinical Nutrition. In 2008, the American Academy of Pediatrics raised the recommended intake for children to 400 International Units (IUs) per day, doubling levels set by the Food and Nutrition Board.
Still, for many, it remains unclear whether they are getting enough of this essential nutrient. Below are some of the little-known facts about vitamin D to help guide you in your decision to supplement.
Vitamin D's safety has been demonstrated at up to 10,000 IUs per day. While the current government recommended daily intake is set at only 200 IUs for anyone under 50 years old, most experts support getting at least 1,000 IUs of vitamin D per day.
According to the 2005-2006 National Health and Nutrition Examination Survey, only 29% of adult men and 17% of adult women had a dietary intake exceeding the 200 IU recommendation.
One cup of fortified milk contains 120 IUs of vitamin D.
The amount of sunlight reaching latitudes above 42 degrees (places north of California and Boston) is insufficient for natural vitamin D creation by the body between November and February.
Sunscreen is important for protecting against skin damage. However, any formulas with an SPF higher than 8 will block the UV rays necessary for natural vitamin D synthesis.
Strict vegetarians, adults over 50, people with dark skin and those who drink alcohol excessively are at increased risk for vitamin D deficiency.
Symptoms of vitamin D deficiency can include fatigue, muscle weakness and bone pain, but symptoms most often go unnoticed.
Liquid drops are great for kids since they can be easily added to a multivitamin or smoothie in varying dosages. Look for formulas without added vitamin B for a better tasting option.
Most studies are done with D3 (also called cholecalciferol). Opt for this form of the vitamin when choosing a supplement since it is more potent than D2 (also called ergocalciferol).
Our practitioners often recommend Pharmaca brand vitamin D or Rx Vitamins Liqui-D3 2000 IU.
If you feel that you might be at risk for low levels of vitamin D, talk with your doctor about having a 25-hydroxy vitamin D test done (by the way, normal ranges are between 30-74 ng/mL). As always, you can also speak with one of our nutritionists or naturopathic doctors about the dosage, formula or brand that might be right for your needs.
Thanks to Alise Hassler, a Certified Nutritional Consultant at Pharmaca in Novato, for her contributions to this article.