Do You Know Your Vitamin D Status?
New research is emerging on the essential role
vitamin D plays in optimum health.
A recent analysis of 18 studies including over 57,000 people found a 7% reduction in mortality in those who took and average of 528 IU daily of vitamin D supplementation. In addition to healthy bone development and maintenance of bone mass, the active form of vitamin D, 1,25-dihydroxyvitamin D, controls more than 200 genes related to vital cellular functions. Various tissues in the nervous, cardiovascular, immune, and glandular systems are influenced by vitamin D. We believe that through these mechanisms vitamin D may reduce the risk of many chronic illnesses including colon, prostate and breast cancers, autoimmune diseases such as multiple sclerosis and Crohn’s disease, diabetes, and cardiovascular disease.
Vitamin D is provided from sun exposure and dietary sources.
During exposure to solar ultraviolet B rays, vitamin D receptors in the skin quickly convert it to the active form of which can be stored in and released from the fat cells. Dietary sources are transported to the liver, and then activated by by the kidneys. Possible causes of Vitamin D deficiency include inadequate sunlight exposure, inadequate dietary intake, impaired absorption of the vitamin from the digestive tract, and impaired conversion of the inactive form to the active form.
Vitamin D deficiency presents a potential health problem for many overweight people. Studies have confirmed that obese individuals have low plasma concentrations of vitamin D. Most of the research has concluded that obesity-associated vitamin D insufficiency occurs because vitamin D from skin and dietary sources remains trapped in fatty tissue instead of being released into the blood stream. The higher the body fat percentage, the lower the blood concentration of vitamin D. Additional studies have demonstrated that people with poor vitamin D status are more likely to suffer from type 2 diabetes as well as the metabolic syndrome.
Blood 25-hydroxyvitamin D level is the best indicator of vitamin D status.
Historically, a level below 27.5 nmol/L was considered a risk factor for the development of bone disorders including rickets and osteomalacia. Now, we believe that the prevention of chronic diseases such as cancer and diabetes may require levels as high as 80 nmol/L. Additional research is needed to determine optimal levels. Sensible sun exposure can provide adequate vitamin D during the summer months. This would require the exposure of one’s arms and legs without sunscreen for 5-30 minutes depending on the time of day, season, and skin pigmentation. Tanning beds can also be used if outdoor exposure is limited. However, it is important to prevent sunburn to avoid the risk of skin cancer.
Food sources of vitamin D are detailed in the list below.
Keep in mind that salmon is not only a good source of Vitamin D, but also provides cardiovascular protective Omega 3 fatty acids.
Vitamin D in Foods
Natural Sources IU
Cod liver oil, 1 Tbsp 1360
Salmon, 3.5 oz cooked 360
Sardines, 1.75 oz, oil drained off 250
Egg yolk, large 20
Liver, beef, 3.5 oz cooked 15
Milk, cow’s, 8 oz 100
Fortified orange juice, 8 oz 100
Fortified margarine, 1 Tbsp 60
Cereals, fortified with 10% DV 40
(3/4-1 cup serving)
Souce: NIH Clinical Center,
Office of Dietary Supplements
Dietary supplements of vitamin D3 (cholecalciferol) are recommended for most individuals in northerly latitudes during the fall and winter months. Although the current recommendations are 200 IU from birth to age 50, 400 IU for adults 51-70 and 600 IU for those over 71, researchers are calling for a change in these recommendations. A minimum of 800-1000 IU for children and adults may be required without sun exposure. Obese patients have higher needs and should take 1000-2000 IU/day to avoid deficiency. For obese persons diagnosed with deficiency, recommended treatment is a high loading dose of vitamin D2 until optimal levels are reached, followed by regular maintenance supplementation.
Vitamin D is emerging as a critical nutrient associated with many chronic diseases, including obesity, putting many people at risk for deficiency.
Understanding the importance of this vitamin and the ways in which you can achieve adequate levels through responsible sun exposure, diet, and supplementation is a very positive step towards long term health and longevity.
Dr. Linda G. Everett is the founder and medical director of Everett Medical: Weightloss and Age Management. Board Certified in Internal Medicine and Age Management Medicine. Dr. Everett has extensive training and experience in Bariatric and Preventive Medicine. She received her undergraduate degree from Johns Hopkins University, and her medical degree from Jefferson Medical College. Dr. Everett is on the medical staff of both Christiana Care Health System and Jennersville Regional hospital, and is a member of the American Society of Bariatric Physicians.