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  • Writer's pictureDr. Corina Dunlap

7 Reasons to Avoid Being "D"- ficient

Worldwide, inadequate vitamin D intake and blood levels is common, and deficiencies can be found on all continents, in all ethnic groups, and across all ages. Some surveys suggest that perhaps half of the world’s population has inadequate blood levels of vitamin D.

Vitamin D is produced by the body in response to the skin being exposed to sun, but can also be acquired by eating fish such as salmon, trout, mackerel, and tuna, certain mushroom-types, fortified milks (including some alternative milk types), egg yolks, fish and beef liver, and cod liver oil.

Risk factors for being “D-ficient” include living above 35 degrees latitude, avoiding sunlight, spending most of the daylight hours indoors, wearing sunscreen, having dark skin, being obese or elderly, having low dietary vitamin D intake, having a condition causing malabsorption (such as lactose intolerance, celiac disease, Crohn’s, or pancreatic insufficiency), exclusively breast-fed infants who do not receive vitamin D supplementation, or taking vitamin D-depleting drugs.

Being “D-ficient” may increase the risk of a host of chronic diseases such as osteoporosis, depression, dental cavities, rheumatoid arthritis, and multiple sclerosis, as well as infectious diseases, such as upper respiratory infections including the seasonal flu. Based on the most up-to-date research, here is a list of the top reasons why adequate levels of vitamin D are so important to our health.

  1. Strengthens Muscles and Bones: Severe vitamin D deficiency in children causes rickets, a condition involving softening of the bones, deformities, muscle weakness, and dental abnormalities.[1] Severe vitamin D deficiency in adults causes osteomalacia, a condition involving softening of the bones, muscle weakness, and bone pain. Both of these conditions can lead to other health complications such as immobility and ill health, and both are treatable with adequate vitamin D intake.

  2. Improves Calcium Levels: Some people either don’t eat enough calcium OR don’t absorb enough calcium. Adequate vitamin D levels increase the body’s absorption rate of calcium.[2] That’s right! If you have enough vitamin D, you will get more calcium from the foods that you eat. Adequate calcium is important not only for bone health, but also muscle and heart health.

  3. Avoiding Seasonal Flu: Research suggests that vitamin D3 supplementation taken during the winter months reduces influenza infections by 42% in school-aged children. This isn’t just referring to all flu types, but also the big nasty Influenza A strains that have the potential to cause the most harm. [3,4]

  4. Multiple Sclerosis (MS): Research shows that long-term vitamin D3 supplementation decreases MS risk.[5,6] This risk reduction is dose dependent and applies more to white women and men than to black and Hispanic groups.

  5. Rheumatoid Arthritis (RA): Older women who have a higher intake of vitamin D3, have a lower risk of developing RA.[7]

  6. Cavities: An analysis of clinical research suggests that vitamin D supplementation significantly reduces the risk of cavities compared to placebo in infants, children, and adolescents.[8]

  7. Seasonal Affective Disorder (SAD): Some preliminary data suggests that those treated with vitamin D have less occurrence of SAD than those untreated.[9]

Seek the professional advice of your physician or health care provider for an individualized assessment and monitoring of your vitamin D status and appropriate treatment plan.


  1. Wharton B, Bishop N. Rickets. Lancet 2003;362:1389-400.

  2. Committee to Review Dietary Reference Intakes for Vitamin D and Calcium, Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Calcium and Vitamin D. Washington, DC: National Academy Press, 2010.

  3. Urashima M, Segawa T, Okazaki M, et al. Randomized trial of vitamin D supplementation to prevent seasonal influenza A in schoolchildren. Am J Clin Nutr 2010;91:1255-60.

  4. Charan, J., Goyal, J. P., Saxena, D., and Yadav, P. Vitamin D for prevention of respiratory tract infections: A systematic review and meta-analysis. J Pharmacol Pharmacother. 2012;3(4):300-303.

  5. Munger KL, Zhang SM, O'Reilly E, et al. Vitamin D intake and incidence of multiple sclerosis. Neurology 2004;62:60-5.

  6. Munger KL, Levin LI, Hollis BW, Howard NS, Ascherio A. Serum 25-hydroxyvitamin D levels and risk of multiple sclerosis. JAMA 2006;296:2832-8.

  7. Merlino LA, Curtis J, Mikuls TR, Cerhan JR, Criswell LA, Saag K. Vitamin D intake is inversely associated with rheumatoid arthritis: results from the Iowa Women’s Health Study. Arthritis Rheum 2004;50:72-7.


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