The Hype
Have you been told that everyone is deficient in Vitamin D and we all need supplements? For the past couple of years, people are rushing to the store to buy high-dose Vitamin D supplements. Just browsing the internet for a few minutes, I found many reports on why we need more vitamin D, from lowering cancer risk, to promoting weight loss, to flu prevention, to lowering the incidence of autoimmune disorders, depression, diabetes, and heart disease. Some people believe that widespread deficiency is due to America’s serious use of SPF products, interfering with our body’s ability to synthesize Vitamin D from the sun. Are we all deficient? Worse, are we all experiencing health issues due to Vitamin D deficiency?
The Breakdown
The Science
Vitamin D is also known as calciferol. In the active form in the body, it is called calcitriol, and is actually a hormone. The DRI (dietary reference intake, previously known as the RDA) for Vitamin D for adults is currently 600 IU’s daily.1 There are many medical doctors and Naturopaths who are recommending upwards of 10,000 IU’s, 20,000 IU’s, and sometimes more. FYI – IU stands for International Unit, and is used as a measurement for some nutrients.
There is substantial and ongoing scientific research about Vitamin D and it’s effects on many different diseases and conditions. Vitamin D deficiency is now being linked to many different cancers, metabolic syndrome (including cardiovascular disease and diabetes and blood glucose metabolism), HIV, and others. Considering the prevalence of all of these health issues in the United States, it is definitely something to continue to study.
Vitamin D status can be assessed via a blood sample testing for 25(OH)D, or 25-Hydroxy Vitamin D. Normal range for this test is 30-74 ng/mL.2 There are plenty of studies indicating that if low, supplementation will bring 25(OH)D levels up to normal range.
My two cents
Your Vitamin D status depends on two things – dietary Vitamin D intake and sunlight exposure. Indeed it has many known functions in the body, such as maintaining proper bone mineral density and promoting calcium absorption from the gut, strong teeth, as an important component in many circulating hormones in the body, and regulating many genes within the body. Historically, we in the medical field presumed that minimal sun exposure and small amounts in our food supply (including milk and cereal fortification) met most people’s needs. Now, it may not be that simple. Consider that according to several studies, Vitamin D deficiency is rising in the United States.3, 4.
What to do? Certainly there are health risks associated with low levels of Vitamin D. Rather than assume you are deficient and invest in high-dose Vitamin D supplements, simply ask your doctor to order lab work for 25(OH)D the next time you get your labs checked. This way, you know your level and can supplement appropriately and safely. If you are taking Vitamin D supplements long-term, get your 25(OH)D measured annually as a part of your annual physical. Be smart and safe. Although toxicity has been rarely reported in the past, it is a risk and people are taking much higher doses than ever before.
Where is Vitamin D in our food supply???
Fish liver oils, egg yolks, cheese, butter, fortified milks, and fortified cereals. That’s about it, besides supplements.
References:
- The Institute of Medicine under the National Academy of Sciences creates the Dietary Reference Intakes for Americans. Dietary Reference Intakes (DRIs) were previously known as the Recommended Daily Allowances (RDAs) for nutrients.
- National Institutes of Health;
http://www.nlm.nih.gov/medlineplus/ency/article/003569.htm
3. Adit A. Ginde, MD, MPH; Mark C. Liu, MD; Carlos A. Camargo, MD, DrPH, Demographic Differences and Trends of Vitamin D Insufficiency in the US Population, 1988-2004,Arch Intern Med. 2009;169(6):626-632.
4. Forrest, Kimberly; Stuhldreher, Wendy; Prevalence and correlates of Vitamin D deficiency in US adults, Nutrition Research, v. 31, p. 48-54
