What does Vitamin D do?
- prevent chronic diseases
- keep your bones and teeth strong and healthy
- reduce inflammation
- regulate growth and activity of your cells
What is the Major Source of Vitamin D?
Most Vitamin D is produced in your body through the sun’s ultraviolet light, which reacts with the 7-dehydrocholesterol precursors on your skin. This reaction converts the precursors to Vitamin D3. In the liver, Vitamin D3 undergoes 25-hydroxylation to form 25(OH)D.1 The best level of 25(OH)D is suggested to be 30ng/ml or above.1
Few foods contain Vitamin D, but some that do include the following: fish (salmon, mackerel, tuna), and fish liver oils are among the best sources of Vitamin D. Beef liver, cheese, and egg yolks contain small amounts of Vitamin D.2
In the American diet, fortified foods provide the most Vitamin D; this includes the U.S. milk supply, fortified with 100 IU/cup of vitamin D.2
Symptoms of Vitamin D Deficiency
- rickets – a condition characterized by bone deformities and growth retardation
- bone pain
- osteomalacia (soft bone)
- frequent bone fractures
How Can I Test for Vitamin D Deficiency?
The SpectraCell Analysis Test is an evidence based test that measures the levels of select vitamins (including Vitamin D), minerals (including calcium), antioxidants, and other micronutrients in your white blood cells. This test is important because nutrient status is a very important component of your health. Every micronutrient plays an important role in optimal functioning of your cells. The SpectraCell Analysis Test will identify any micronutrient deficiencies you may have; identifying and correcting deficiencies is essential in maintaining optimal health.
The SpectraCell Analysis Test is available Monday through Friday from 8:30am-3:30pm
Vitamin D and Cardiovascular Disease
Studies have shown that low 25(OH)D levels are associated with cardiovascular heart disease and congestive heart failure.1
Vitamin D and Hypertension
Results from cross-sectional studies show an inverse relationship between Vitamin D levels and blood pressure – the higher the Vitamin D levels, the lower the blood pressure.1 Other studies show that high blood pressures were associated with higher levels of parathyroid hormone (PTH), a hormone that increases blood calcium concentration by removing calcium from your bones.1
Vitamin D and Diabetes
Insulin is secreted by cells in the pancreas called beta cells. According to a meta-analysis, Vitamin D appears to influence the response of insulin to elevated glucose levels; Vitamin D may also regulate extracellular calcium to ensure that there is normal calcium influx through the cell membranes and intracellularly. This is important because insulin release by beta cells is dependent on calcium.3 Furthermore, calcium is needed in insulin-mediated intracellular processes in tissues that are insulin-responsive, such as adipose tissue and skeletal muscle.3 Therefore, changes in the concentration of calcium in the cell may lead to insulin resistance because of impaired signaling in the cell. Insulin resistance, in turn, can lead to diabetes.
Vitamin D and Obesity
Vitamin D deficiency has been linked to obesity.1 A recent study found that obese individuals have lower levels of 25(OH)D and higher PTH levels than do non-obese individuals. Vitamin D is fat soluble and therefore is stored in adipose tissue.4 Results from the study found identical concentrations of Vitamin D among obese and non-obese patients after exposure to UV-B irradiation.4 However, the increase in blood Vitamin D concentration was less in obese patients than in non-obese patients.4 This suggests that obesity does not affect the capacity of the skin to produce Vitamin D, but obesity may alter the release of Vitamin D from the skin to the bloodstream because the excess adipose tissue hinders Vitamin D’s release into the bloodstream.4
Calcium and Metabolic Syndrome
A research study using data from the Women’s Health Study found an inverse relationship between calcium intake and prevalence of metabolic syndrome. This study did not find a relationship between Vitamin D intake and metabolic syndrome, but the effects of Vitamin D are dependent on the presence/absence of other nutrients such as calcium. Therefore, low serum calcium levels influence Vitamin D action, and this affects your health.
George Mateljan Foundation (2009). Vitamin D. Retrieved February 16, 2009, from http://ods.od.nih.gov/factsheets/vitamind.asp#en23.
Pittas, A.G. et al. (2007). The role of vitamin D and calcium in type 2 diabetes. A systematic review and meta-analysis. The Journal of Clinical Endocrinology & Metabolism, 92(6), 2017-2029.
Wortsman, J., Matsuoka, L.Y., Chen, T.C., Lu, Z., & Holick, M.F. (2000). Decreased bioavailability of vitamin D in obesity. American Journal of Clinical Nutrition, 72(3), 690-693.