Who is at Risk for Vitamin D Deficiency?
One-third of Those with Low Serum Levels Have No Known Risk Factors
Nov 3, 2009
Vitamin D deficiency affects people of all ages. Despite fortification of various foodstuffs with this vital nutrient, large segments of populations – even those in wealthier nations – exhibit serum levels that are low enough to place them at risk for health problems.
Owing to inadequate vitamin D levels, 50 percent of elderly North Americans and two-thirds of all persons in the remainder of the world fail to maintain adequate bone density or tooth attachment. (Norman AW, et al. 13th workshop consensus for vitamin D nutritional guidelines. J Steroid Biochem Mol Biol. 2007;103[3-5]:204-205)
In a 2002 study of 142 healthy persons (most of whom regularly consumed milk and supplements), participants aged 18 to 29 years with no known risk factors for deficiency exhibited the lowest serum levels of vitamin D. (Tangpricha V, et al. Vitamin D insufficiency among free-living healthy young adults. Am J Med. 2002;112[8]:659-662)
Approximately one third of persons with documented vitamin D deficiency have no identifiable risk factors for such deficiency. (Schneider DL. Vitamin D and skeletal health. Curr Opin Endocrinol Diabetes. 2006;13[6]:483-90)
Vitamin D Deficiency Has Been Linked to a Variety of Medical Conditions
In the 19th century, the association between vitamin D deficiency and rickets was defined and fortification of foods contributed to the resolution of this significant health issue. Vitamin D’s importance in preventing osteoporosis in elderly persons has long been recognized as well.
More recently, though, vitamin D deficiency has been linked to a variety of pathologic conditions in people of all ages; vitamin D supplementation has been shown to correct or alleviate many of these disorders:
- Fall risk: Falls are the leading cause of death in persons older than 65 years. Vitamin D therapy improves proximal muscle strength and reduces the incidence of falls among the elderly.
- Fracture risk: Regular vitamin D supplementation (800 IU daily) is associated with a lower incidence of fractures among elderly individuals who experience falls.
- Osteoporosis: Vitamin D replacement is an important factor in preventing osteoporosis, and supplementation will increase bone mineral density in individuals who already suffer from osteoporosis.
- Cardiovascular disease: Suboptimal vitamin D levels are associated with increased risk of cardiovascular disease; hypertension, diabetes, and obesity are all linked to low serum 25-hydroxyvitamin D levels.
- Cancer risk: Although data are conflicting, studies suggest that the risk of colon cancer is inversely related to blood levels of vitamin D. Likewise, the incidence of prostate and breast cancers may be reduced in people with higher vitamin D intake.
- Depression: Vitamin D deficiency has been associated with depression, low mood, and decreased cognitive function.
- Autoimmune illness: The incidence and prevalence of several autoimmune diseases, including multiple sclerosis, type 1 diabetes, and rheumatoid arthritis, increase with increasing latitude. This suggests a connection between these illnesses and decreased tissue levels of vitamin D.
(Adapted in part from Bordelon P, et al. Recognition and management of vitamin D deficiency. Am Fam Phys. 2009;80[8]:841-46)
Who Is at Risk for Vitamin D Deficiency?
Although population studies reveal that otherwise healthy persons may indeed be suffering from subclinical vitamin D deficiency, some groups are at particularly high risk:
- Persons older than 65 years
- Infants that are exclusively breastfed without vitamin D supplementation
- Individuals with dark skin (increased pigment impairs production of vitamin D from sunlight exposure)
- Individuals with insufficient sunlight exposure
- Persons with sedentary lifestyles
- Obese individuals (BMI greater than 30)
- People who take medications that interfere with vitamin D absorption or metabolism (anticonvulsants, glucocorticoids, etc.)
Clinical Signs of Vitamin D Deficiency
Unfortunately, serum levels of vitamin D can be low for some time without causing overt clinical signs or symptoms. Aside from rickets, the classical manifestations of deficiency include:
- Bone pain, often throbbing and severe, in the pelvis, lower extremities, and low back (women often exhibit symmetric low back pain)
- Muscular aches
- Impaired balance or increased incidence of falls
- Weakness of the proximal muscles (i.e., shoulders, buttocks, thighs)
Currently, the recommended daily vitamin D intake is 400 IU for healthy children and adolescents and 800 to 1,000 IU for healthy adults. Vitamin D3 (cholecalciferol) is the preferred form for supplementation, although some physicians may still recommend vitamin D2 (ergocalciferol) for treatment of vitamin D deficiency and for maintenance.
Vitamin D is essential for maintaining musculoskeletal, neurologic, cardiovascular, and immunologic health. The prevalence of vitamin D deficiency in otherwise healthy populations is higher than one would expect, given the levels of fortification in many foods. Apparently, in the absence of conditions that contraindicate it, most individuals would benefit from regular vitamin D supplementation.
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