Vitamin D: A little drop of sunshine | On Health

Doctor at Mercer Island Pediatrics explains the benefits of vitamin D.

  • Thursday, January 18, 2018 12:11pm
  • Opinion
Dr. Elizabeth Evans

Dr. Elizabeth Evans

By Dr. Elizabeth Evans

Special to the Reporter

One of the most common questions I get asked when discussing diet at a well child visit is “Does my child need to take a vitamin?”

With sales over $20 billion a year in the U.S., store shelves are overflowing with a multitude of vitamins and supplements. Most often the answer is no with one exception and that is vitamin D.

Vitamin D is a fat-soluble vitamin known to be important for a myriad of bodily functions. It promotes and maintains calcium absorption leading to healthy bone development. Without enough vitamin D, the bones can have deficient mineralization leading to bowing and abnormal growth.

Although most people know that vitamin D is needed for healthy bones, it also benefits the immune system and reduces inflammation.

New research suggests that vitamin D may have a role in preventing cardiovascular disease, multiple sclerosis and certain cancers.

Vitamin D is synthesized by the body from sun exposure but also can be obtained in food and supplements. Our skin synthesizes vitamin D3, cholecalciferol, from the ultraviolet light of the sun. It’s an efficient system, creating our daily intake in just 15 to 30 minutes of sun exposure.

However, during our Northwest winters, getting that amount of sun can be difficult. Even on our sunniest days, our children are often so bundled up from the cold that there is little skin exposed. Add in other factors such as skin type, time of day, cloud cover and latitude and the amount of sun exposure needed gets more complicated.

Unfortunately, very few foods naturally contain vitamin D. The highest levels can be found in fatty fish such as salmon and tuna, but smaller amounts can be found in eggs, cheese, mushrooms and beef liver.

The most common fortified food in the U.S. is milk. The dairy industry started fortifying milk with vitamin D in the 1930s as a way to prevent a severe bone disease called rickets. Since then milk, infant formula, and some orange juice, breakfast cereals, and dairy products have been fortified.

For those who have limited sun exposure and are not getting their recommended amount through food, supplementation may be necessary. The National Academy of Medicine released their recommended dietary intake requirements in 2010.

For infants aged less than a year old, 400 I.U. (international units) was recommended. The American Academy of Pediatrics agrees and therefore recommends vitamin D supplementation for all breastfeed babies since levels are low in human milk.

Infant formula is fortified with vitamin D, however babies drinking less than 32 ounces a day may still need a supplement. For children from age 1 to 18 and adults through age 70, the recommended dietary allowance is 600 I.U. a day.

For perspective, one cup of fortified milk contains approximately 100 I.U. Fortunately, vitamin D for supplementation is easily found in multiple forms including drops, gummies, chewable tablets and capsules.

Remember, vitamin D is fat-soluble so it is possible to overdose from excessive supplementation.

As we enter our shortest days of winter here in the Pacific Northwest, don’t forget to ask your physician about supplemental drops of sunshine for your children.

Dr. Elizabeth Evans has been practicing pediatrics for over 15 years. She lives on Mercer Island with her husband and three daughters. She is actively involved in the community with Girl Scouts and the Lakeridge Elementary PTA.

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