Vitamin D: What does it do and how to get it

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Vitamin D is counted among the essential vitamins and minerals to keep the body healthy. Find out why and how you can add more Vitamin D to your diet.

Meet vitamin D

Vitamin D is a fat-soluble vitamin that is naturally present in very few foods.  It is often added to some foods – for example, ‘fortified’ cereals and milk – and available as a dietary supplement--though it’s always best to get nutrients from natural sources, when possible. Vitamin D is also produced when ultraviolet rays from sunlight are absorbed through the skin, which triggers a Vitamin D synthesis reaction.

What it does

Vitamin D is a vitamin the body cannot do without.  It helps the body absorb calcium, it promotes cell growth and immune function, and reduces inflammation.  Vitamin D and calcium together help prevent osteoporosis in older adults. Without an adequate supply of Vitamin D, bones can easily become brittle, thin and misshapen and the body cannot properly heal itself or carry out basic cellular functions.

Where to get it

Vitamin D does not occur naturally in many foods without those foods being fortified. Often, breakfast cereals and milk are fortified with vitamin D and there are a variety of vitamin D supplements on the market.  But the best option is to get vitamin D from food.

How much do you need?

Like all vitamins and minerals, how much one needs to consume on a daily basis depends on a variety of factors, including age and gender.  Here is what the U.S. Government recommends: Both male and female adults should get at least 600 international units (IUs) or 15 micrograms (mcg). Male and female children should consume 400 IUs, or 10 mcg and adults over 70 years old should consume 800 IUs or 15 mcg.

Cod liver oil

It may sound gross but the National Institutes of Health say that cod liver oil has one of the highest concentrations of vitamin D. One tablespoon provides 340 percent of the daily amount of vitamin D recommended by the government.

Swimming in vitamin D

For the less adventurous, many fish meats are naturally high in vitamin D. Three ounces of cooked swordfish has 142 percent of the recommended daily value of vitamin D.  Three ounces of salmon provides 112 percent and three ounces of canned tuna fish provides 39 percent.

A smattering of sources

With the exception of cod liver oil and various fish, Vitamin D is not abundantly available in most foods, but these foods have at least 10 percent of the daily recommended value of Vitamin D:

  • Orange juice (fortified with vitamin D)
  • Milk (fortified with vitamin D)
  • Yogurt (fortified with vitamin D)
  • Eggs
  • Liver

Soak up the vitamin D

Finally, vitamin D can be obtained through sun exposure.  This process happens when ultraviolet rays from sunlight strike the skin and trigger a vitamin D synthesis response. Many people will satisfy at least some of their vitamin D needs through sun exposure.  Generally speaking, five to 30 minutes of sun exposure between 10 and 3 p.m. twice a week will provide a good amount of vitamin D synthesis.

But don't forget sunscreen

It is true that wearing sunscreen will limit the amount of vitamin D absorbed by the sun’s rays.  But that same sunscreen will also save your skin from sunburn, premature aging and potentially, skin cancer. Considering the variety of other sources of vitamin D that are not directly linked to skin cancer, it is always a good idea to wear sunscreen and sacrifice the vitamin D exposure rather than risk melanoma later in life.


National Institutes of Health, Vitamin D fact sheet:

Mayo Clinic, Vitamin D: