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Here’s another reason to enjoy being outdoors-your body makes vitamin D from sunshine.  The amount of vitamin D you make is dependent on the season, where you live, your skin color, and age.  People with type 1 or type 2 diabetes have a higher incidence of vitamin D deficiency.  Vitamin D deficiency is a common nutrient deficiency.  In the U.S. it’s estimated that 40% of adults are deficient in vitamin D.  Higher rates of deficiency are seen in people who are Hispanic or African-American.  Worldwide, it’s estimated that 15% of the population are vitamin D deficient.  Vitamin D deficiency is more common in Northern climates which have limited sun exposure in the winter.  However, vitamin D deficiency is still a problem even in parts of tropical countries with adequate sun exposure.  

The Roles of Vitamin D

Vitamin D is needed to absorb calcium and phosphorus which help to maintain bone density.  Without enough vitamin D, bones become brittle and diseases like osteoporosis and osteomalacia are known complications of vitamin D deficiency. Low vitamin D levels have also been associated with other diseases such as diabetes, heart disease, cancer, multiple sclerosis, depression, and lung disease; although the evidence is not as strong as it is with bone diseases.  Vitamin D has anti-inflammatory properties and helps to support immune health.  Higher levels of vitamin D have been associated with a lower risk of type 2 diabetes in some studies but not others.  This is thought to be due to a possible effect of vitamin D in improving insulin secretion and sensitivity, β-cell function, and decrease in insulin resistance

Risks for Vitamin D Deficiency

A variety of people may be at risk for vitamin D deficiency.  This includes people who have diabetes.  Other factors to consider for possible vitamin D deficiency are:

  • Old age
  • Dark skin color
  • Obesity and weight loss surgery
  • Health conditions such as chronic kidney disease, liver disease, cystic fibrosis
  • Gastrointestinal issues such as Crohn’s disease, celiac disease, fat malabsorption, or gastrectomy
  • Vitamin D deficient diets including vegetarians, vegans, and people who are lactose intolerant 

Vitamin D Foods

There are only a few foods that naturally contain vitamin D.  Fatty fish (salmon, sardines, herring, and mackerel) and cod liver oil are good sources of vitamin D.  Egg yolks, beef liver, and cheese contain smaller amounts of vitamin D.  Most dietary vitamin D comes from fortified foods such as milk, yogurt, dairy alternatives, and cereals.  Many countries don’t fortify foods and beverages as the U.S does.  For example, South Asian countries rarely fortify dairy products with vitamin D.  Dietary vitamin D, without supplements, accounts for only 10-20% of total vitamin D. 

If you have diabetes and have one of the risk factors listed above, talk with your healthcare team about testing your vitamin D level.  Vitamin D supplements are available in two forms: vitamin D3 (cholecalciferol) or vitamin D2 (ergocalciferol).  Excessive vitamin D from supplements can be harmful to your heart, blood vessels, and kidneys.  Talk with your healthcare team before starting any supplements.  The good news is that you can’t overdose on vitamin D from sun exposure, so enjoy some time outside when you can. 


by Christine McKinney, RD LDN CDE





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