June 11, 2019

Shedding light on good vitamin D health

A silhouette of a hand holding up a vitamin D capusle to the sun

Madison, Wis. — Spring is here, the days are getting longer and warmer – the perfect time to head outside for some sun-on-skin contact and a vitamin D boost.

Exposing our bare skin to sunlight is one way to get the vitamin D that our bodies need, but what is the right amount of sun that we need for optimal vitamin D levels and can we reach those levels in other ways?

Apple A. Bodemer, MD, UW Health dermatologist, says that sunlight does contribute to raising vitamin D levels, but exposing our skin to the sun for extended durations can have adverse effects. Unprotected UV exposure should be limited to 10 minutes, said Bodemer, and it doesn’t take a lot of body surface area to satisfy your vitamin D needs. A quick trip to the store in a short-sleeve shirt on a sunny day is often enough.

“I see a lot of people who have more problems with the side effects from the sun, meaning UV damage and skin cancers,” said Bodemer, adding that multivitamin and vitamin D3 supplements will make up for any deficiencies.

She recommends 2,000 to 4,000 international units (IU) of vitamin D a day for her patients with low levels and to have levels re-checked in about three months. One hesitation she has when boosting vitamin D levels is for people with a history of kidney stones, since vitamin D overload can cause kidney stones to form. The UW lab considers normal vitamin D levels to be between 30 to 80 nanograms per milliliter (ng/mL).

“I like to see people between 45 and 55 ng/mL, right around that 50 mark,” said Bodemer.

Taking a quality multivitamin will give you the basic recommended daily allowance of vitamin D, and you can supplement above that as long as you stay within reasonable levels. A quality multivitamin is good for anybody at any age because it helps to fill in those gaps in our diet, but Bodemer said that it should not be used in place of fruits, vegetables and other nutrient-rich foods.

Make good food choices

Vitamin D can also be obtained through some foods. Be sure to check the ingredients list to make sure they contain vitamin D3, which is the active form of the vitamin that our body needs. Foods with vitamin D include:

  • Fatty fishes, such as salmon, mackerel and tuna

  • Fortified cereals

  • Fortified milks

  • Fortified yogurts

  • Fortified cheese

  • Fortified orange juice

  • Sardines, canned in oil

  • Eggs (vitamin D is in the yolk)

  • Liver and beef

Why do we need vitamin D?

Vitamin D is used by the body to treat weak bones, bone loss, and it promotes general strengthening of bones and overall bone health. It is also used in the prevention of rickets, a bone disease found in children and caused by vitamin D deficiency.

Bodemer said we don’t know the full extent of what vitamin D does for our bodies, but it does have some hormone-like effects. Low vitamin D levels are associated with certain cancers – breast and colon being the most common. There are also links with hair loss, mood disorders like depression, chronic fatigue and the skin condition psoriasis.

“A lot of times when you supplement vitamin D it doesn’t take the problem away completely,” said Bodemer. “It is likely that the vitamin D deficiency is a part of the whole picture, but not likely the sole cause of psoriasis, hair loss or depression.”

Who’s at risk

Certain demographic groups are at higher risk for low vitamin D, but Bodemer said that no two people are the same.

“I have lots of patients who are farmers who have spent their lives in the sun and they have a history of skin cancer, and I check their vitamin D levels and they are still low," she said. "It goes to that question that not everybody synthesizes it efficiently in the skin.”

Groups at higher risk for low vitamin D:

  • Infants that are exclusively breast fed are often vitamin D deficient, since breast milk contains little vitamin D

  • Elderly people often have decreased enzyme production, which lowers the body’s ability to convert the necessary vitamin D levels

  • People with darker skin have decreased conversion of vitamin D in the skin because the melanin blocks some of the UV radiation exposure

  • People who are obese or malnourished

  • People who are institutionalized in rehab centers or nursing homes

When to test vitamin D levels

If you fall in any of the below categories, you might be at higher risk for vitamin D deficiency. Your primary care physician is the best person to say whether you should have your vitamin D levels tested.

  • Photosensitive disorder: People with a photosensitive disorder (sun allergies) who consciously protect themselves from the sun and are not going out in the middle of the day.

  • Skin cancer history: People with a history of skin cancer who are vigilant about sun protection.

  • Psoriasis diagnosis: Patients newly diagnosed with psoriasis.

  • Breast and colon cancers: People with a strong family history of colon or breast cancers.

  • Fatigue: People with chronic fatigue.

  • Mood disorder: Patients diagnosed with depression or other mood disorders.

  • Long-term steroids: People on a long-term steroid prescription.

  • GI disease: People with GI diseases might not absorb nutrients as well as other people.