The Vitamin D Deficit

6 min read  |  June 27, 2018  | 

In the fourth of our five-part series focusing on vitamins, Sheah Rarback, a licensed dietitian nutritionist with the University of Miami Health System, discusses vitamin D.

There’s unsettling news about this vitamin.

Nearly 90% of African-Americans, Hispanics, and Asians and 75% of whites are vitamin D deficient.

What’s going on?

Sheah Rarback: Some health experts blame two things. Americans are spending more time indoors, which means we’re getting less of the sunshine that helps our bodies produce vitamin D. The obesity epidemic isn’t helping either – excess body fat interferes with our ability to use this vitamin.

There is confusion around this issue, however. Almost all of my patients’ blood tests show low vitamin D levels. However, are they deficient in a way that impacts health or just low on the reference range of 20-100 ng/ml? That is a tiny, yet essential amount for maintaining proper body function.

Before jumping to conclusions, consider other risk factors. Are you obese? Are you over age 70?  Our bodies don’t process vitamin D as well as we get older. Are you less active and do you stay inside most of the time? Are you at risk for osteoporosis? Seizure medications, celiac, Crohn’s and certain kidney diseases also affect vitamin D. If you have any risk factors, get tested and supplement if your D levels are low.

Other than keeping our bones strong, why is D important?

Rarback:  Vitamin D is different from other vitamins. It behaves more like a hormone. A precursor to melatonin production, it regulates sleep cycles and blood pressure, and fights infections. Some studies say it also affects brain function and provides protection against cancer.

What’s the best way to get my daily dose of D?

Rarback: There’s controversy around this, too. While sunshine triggers vitamin D production within the body, we don’t store this vitamin. Some health experts recommend sun exposure several times a week, without sunscreen or applied to the face and hands only. How much sunlight you need varies, depending on skin type, age, time of day, and climate. According to an article published by the National Institutes of Health, 30 minutes in the summer sun generates 50,000 International Units (IU) of vitamin D in most light-skinned people. That same exposure time in dark-skinned people produces 8,000–10,000 IU; in tanned people, it yields 20,000–30,000 IU. (IU is used to measure the amount of a fat-soluble vitamin. For example, 400 IU equals 10 micrograms.)

According to UHealth dermatologist Dr. Shasa Hu, the sunnier the climate and the lighter your skin, the less sun you can safely tolerate.  If you’re a pale, freckly-skinned redhead, you’ve got about five minutes in the summer sun before risking sunburn. If you’re darker skinned and never burn, she says you can generally tolerate up to 15-20 minutes under the hot mid-summer sun before needing sunscreen and UV protective clothing.

Dr. Hu cautions people to not rely on sunshine for vitamin D. She feels it’s safer and more reliable to replenish vitamin D with oral supplements. That way, you spare yourself any risk of skin cancer and premature aging.

What can I eat and drink to boost my vitamin D levels?

Rarback: Eat cold water fatty fish like tuna, wild salmon or halibut twice a week. All three, along with sardines, mackerel, and trout, contain vitamin D. They also improve heart and brain health. One of the best sources – if you can tolerate it – is a tablespoon of cod liver oil. Other D-rich foods are egg yolks, milk, yogurt, portabella and shitake mushrooms. Like people, vitamin D in mushrooms increases when exposed to sunshine. Place them in a sunny window for two days before eating.

If you prefer plant-based milk over dairy milk, check the label. Most milk substitutes are fortified with vitamin D2, which the body does not absorb as well as D3.

If I choose to supplement, how much should I take?

Rarback: If your bloodwork reveals a deficiency, the recommended daily amount for adults and pregnant women is 600 IU of vitamin D daily. People over age 70 need 700 IU daily. Children under 12 months need 400 IU, if deficient. Make sure your supplement contains D3. Most calcium supplements contain D, so women should read the label before adding more.

Can you take too much vitamin D?

Rarback: The upper tolerance limit is 4,000 IU, but you don’t want to overdose on any vitamin. There’s vitamin D in food, multivitamins, and calcium supplements. In sunny South Florida, we get a dose of D almost any time we’re outside.

Earlier, you mentioned the confusion about the widespread vitamin D deficiency. When will we know more?

Rarback: Food is complex and the way our bodies metabolize it is complex, so consumers are understandably confused. Future studies should provide better information. Until then, get your comprehensive bloodwork done annually, stay active, and eat a varied, healthy diet.

The Takeaway:

Vitamin D builds strong bones, regulates sleep and blood pressure, and fights infection. It’s found in tuna, wild salmon and other fatty fish, as well as dairy, mushrooms, and egg yolks. You can boost your D levels with brief, unprotected sun exposure a few times a week. If you prefer to avoid the sun and if testing reveals a deficiency, take an oral supplement. Adults need 600 IU of D daily until age 70, when it raises to 700 IU. Babies under 12 months need 400 IU daily. If you’re overweight, sedentary, and don’t get outside often, get your blood tested. The same holds true if you take seizure medication or have kidney or digestive diseases. All of those conditions affect vitamin D levels.

Source: *National Health and Nutrition Examination Survey

Gianna’s Salmon Paradise


  • 1 cup fresh orange juice
  • ¼ cup fresh lemon juice
  • 1 tablespoon low-sodium soy sauce
  • 2 tablespoons extra-virgin olive oil
  • 2 tablespoons minced garlic
  • 1 teaspoon chopped parsley
  • 1 pound salmon fillet, skin removed

Salmon Cakes:

  • ½ cup whole-grain seasoned bread crumbs
  • 2 medium eggs
  • 1 ½ tablespoons Pecorino Romano or Parmesan grated cheese
  • 6 basil leaves, finely chopped
  • 1 tablespoon fresh lemon juice
  • ½ teaspoon lemon zest
  • ¼ cup chopped fresh spinach
  • ¼ teaspoon salt
  • 1/8 teaspoon ground black pepper
  • 1 teaspoon Dijon mustard
  • 1 teaspoon minced garlic
  • ¼ cup shredded carrots

Pickle Sauce:

  • 2 tablespoons dill pickle, diced
  • 1 tablespoon pickle juice
  • 1 tablespoon low-fat mayonnaise
  • ¼ cup low-fat plain Greek yogurt
  • ½ tablespoon fresh lemon juice


  1. To make the marinade: In a large bowl, whisk together all ingredients, adding salmon last. Marinate up to 1 hour in the refrigerator.
  2. To make the salmon cakes: Preheat oven to 400°F. In a nonstick skillet over medium heat, cook salmon with ¼ cup of marinade, about 6 minutes per side or until both sides are slightly opaque. Let cool. On a large nonstick baking sheet or one lined with parchment or greased with oil or nonstick cooking spray, pull apart cooled salmon using 2 forks. Add in all ingredients and mix with your hands, forming 4 cakes. Bake about 10 minutes or until golden brown on the bottom, then carefully flip to cook the other side, about 10 minutes.
  3. To make the pickle sauce: In a medium mixing bowl, combine all ingredients. Top cooked salmon cakes with 2 teaspoons pickle sauce and serve with salad.

Serves 4.

Nancy Moreland is a contributing writer for UMiami Health News.

Tags: healthy diet, Nutrition, vitamin D, vitamin deficiency

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