By Cathy Rosenbaum PharmD MBA RPh
July 12, 2014
Vitamin D’s Purpose
Vitamin D is found naturally in our body. It maintains normal blood concentrations of calcium and phosphorus, and helps our bones stay strong. Interestingly, the body manufactures vitamin D from cholesterol, through a process triggered in the skin by UVB rays from sunlight. Vitamin D is called ‘the sunshine vitamin.’
Per the Institute of Medicine, “despite the many claims of benefit surrounding vitamin D, the evidence does not support a basis for a causal relationship between vitamin D and many of the health outcomes purported to be affected by vitamin D intake.” Some of these claims yet to be proven in well designed human clinical studies include antioxidant, anti-inflammatory, and anti-cancer indications.
Reasons for Low 25-(OH)-Vitamin D Blood Levels
We require a certain level of 25-(OH)-vitamin D in the blood for health. That level can be measured by a simple blood test you can request from your doctor. If you have not yet had your blood tested or it has been awhile since your last blood level drawn, you may wish to ask your doctor to order a 25-(OH)-vitamin D level. The test will determine if you might benefit from supplementation or nutritional changes in your diet to increase vitamin D if your blood level is low (visit http://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional for more information).
Since we’re talking about bone health, it is important to monitor for osteopenia or osteoporosis by way of a DEXA scan. Talk with your doctor about ordering a DEXA scan to measure bone density if you have not had one for several years (visit the National Bone Health Alliance @ www.nbha.org for more information).
25-(OH)-vitamin D blood levels may be low due to reduced exposure to sunlight (e.g., less than 20 minutes of exposure a few times a week), reduced gastrointestinal absorption or nutritional intake, Crohn’s Disease, reduced kidney conversion to the active vitamin form, or from medication interactions such as statins for cholesterol lowering (visit http://www.livestrong.com/article/282052-vitamin-d-deficiency-caused-by-prescription-medication ).
Don’t just start taking vitamin D because you think you need it. You might already be getting enough from sunlight exposure as well as your diet. The Institute of Medicine recommends 600 IU – 800 IU vitamin D3 daily from food or supplements unless otherwise directed by your doctor.
Sources of Vitamin D
Vitamin D can be found in sardines, wild salmon, herring, mushrooms exposed to UV light, fortified milk, yogurt, and breakfast cereals, egg yolks, beef liver, canned tuna, cod liver oil, and cheese.
Vitamin D2, or ergocalciferol, is the form found in prescription strength capsules.
Vitamin D3, or cholecalciferol, is the form found in most over-the-counter vitamin D products.
Vitamin D3 is also available in a variety of dietary supplements. Since there are so many different supplement doses on the market, you may wonder why some people are taking larger doses. Talk to your doctor about your individual needs. Mega doses of vitamin D can cause hypervitaminosis long term if blood levels are found to be excessive.
Fat soluble vitamins like vitamin D can accumulate in the body over time. Symptoms of vitamin D toxicity include headache, diarrhea, nausea, increased blood pressure, anorexia, weight loss, increased thirst, weakness, nervousness, and with long term extreme doses, abnormal heart rhythms. Many of these might not be attributed to vitamin overuse, but confused with other medical conditions. For more information on long term vitamin D safety, visit www.healthlettermayoclinic.com (Sept 2009).
Importance of Exercise for Bone Health
Finally, because bone density decreases after the age of 30 years, bone stressing exercise is important at any age and helps to preserve bone strength. The areas of risk for bone density loss include the wrists, hips, and spine. Talk with your doctor about an exercise program that is right for your individual needs.
“The light of the eyes rejoices the heart, and good news refreshes the bones.” Proverbs 15:30