Vitamin D: The Sunshine Vitamin

by Jeannie Versagli

It’s surprising to me that today there are individuals with vitamin D deficiencies. To think that a vitamin derived from sunshine would be lacking in the body is shocking.  How can this be so?

While Vitamin D is produced by the sun and absorbed via the skin, how we effectively utilize the vitamin from this source is dependent on a number of factors – which season we are in, the time of the day, the length of day, cloud cover, smog, skin melanin content, and sunscreen.  Cloud cover reduces UV energy by 50%, and shade (including that produced by severe pollution) reduces it by 60%.  UVB light does not penetrate glass, so exposure to sunshine indoors through a window doesn’t get the job done either.

So how do you get your daily dose? For starters, the Hockessin area is in the Mid-Atlantic region and the only time of the year that you can absorb adequate Vitamin D is from March to November, so plan to supplement from December to February. Before you go outside basting in the cold now that March is upon us, be sure to follow these guidelines to keep safe. It’s important to be mindful of the risk of developing skin cancers! Researchers suggest 5 to 30 minutes of sun exposure between 10 am and 3 pm at least twice a week to the face, arms, legs, or back without sunscreen, to produce adequate Vitamin D synthesis during our Mid-Atlantic time frame.

Woman outside in sun

While now you’ve got the information to fuel your sun-bathing, you still may not be able to get enough Vitamin D from the sun. So what now?

Well, very few foods have natural sources of vitamin D available.  Fatty fish such as salmon, tuna, swordfish, and mackerel provide the most natural sources of Vitamin D.  Smaller amounts are found in egg yolks and liver.  Because of this, the food industry fortifies foods such as milk products, ready to eat cereals, orange juice, yogurt, and margarine with Vitamin D. Be sure to incorporate some of these foods into your regular diet if you are concerned or have been told that you aren’t getting enough of the sunshine vitamin.

So, what does Vitamin D do, exactly?

Vitamin D has many functions, but the one we are most familiar with is bone health. Building strong bones requires the presence of calcium and Vitamin D to work together. Research is now suggesting that Vitamin D may play roles in reducing inflammation, enhancing cardiovascular health, aiding in neuromuscular function, and it is also is essential for musculoskeletal structure, function, and strength. 

Are you at risk of Vitamin D deficiency?

The ability to synthesize Vitamin D via the skin decreases as we age.  We see this with the elderly population, who often have low levels of this vitamin. When treated with Vitamin D those individuals often experience improvement in their ability to maintain their balance.

Individuals with inflammatory bowel disease and other conditions causing fat malabsorption have an inability to absorb Vitamin D because its absorption depends on the gut’s ability to absorb dietary fat.  Conditions such as celiac disease, Crohn’s disease, ulcerative colitis, and gastric bypass surgery place you at risk of having low levels of Vitamin D, which would require supplementation.

mother holding infant

Infants who are breastfed are another large population that is at risk for deficiency. It is recommended to supplement these infants with 400 IU of Vitamin D per day which is the RDA standard at that stage of life.

What about athletes?

New research is suggesting that muscle injuries in athletes are a result of low levels of Vitamin D.  A study presented at the American Academy of Orthopedic Surgeons Annual Meeting in March of 2015 found that 10% of the participants had severe deficiency of Vitamin D, which resulted in a higher prevalence of lower extremity muscle strains and core muscle injuries.

If you are experiencing any of the following symptoms, I would recommend that you discuss it with your physician to rule out a Vitamin D deficiency:

  • Muscle fatigue
  • Overall general tiredness
  • Back and bone pain
  • Depression
  • Bone loss (osteoporosis)
  • Hair loss
  • Frequent illness
  • Muscle pain

While the difficulty to synthesize Vitamin D increases as we age, deficiency is not age-related. Vitamin D deficiencies can occur young in adults all the way through elderly

As with any vitamin, safety is the number one concern.  Work with your Doctor to determine if you have a Vitamin D deficiency.  If there is a therapeutic need, your doctor will prescribe a Vitamin D supplement and should continue to monitor your levels over time to assure you are meeting your estimated needs of this vitamin.

jug of milk with sunflowers in background

Work to incorporate foods that provide good sources of Vitamin D into your diet along with the appropriate safe sun exposure. Trying these two methods together gives an individual the opportunity to provide the necessary Vitamin D needed to remain healthy. Nutrition’s pathway to health begins with self-awareness, nutrition, and the outdoors.

Guidelines for Vitamin D daily intake.

Infant to 12 months400 IU
Year 1 – 70600 IU
Year 71 and above800 IU
Pregnant and Breastfeeding600 IU

Examples of estimated Vitamin D content of foods.

3.5-ounce serving of wild-caught Salmon988 IU of Vitamin D*
3.5-ounces of Trout291 IU of Vitamin D*
3.5-ounces of canned Tuna154 IU of Vitamin D*
8 ounces of milk124 IU of Vitamin D*
4 ounces of oatmeal/cereal55-154 IU of Vitamin D*

 *Estimated values


Hockessin Athletic Club opened its doors on June 10 2007. Boasting over 100,000 sq. ft., a 5-pool aquatics complex, and over 200+ weekly group and aqua fitness classes, it is Delaware's premier fitness destination. 100 Fitness Way, Hockessin, DE ·

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