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August 16, 2021


Lindsay Delk, RDN
How To Prevent Vitamin D Deficiency

Fact Checked By Lindsay Delk, RDN
 August 16, 2021

Vitamin D Deficiency

Over a billion people worldwide have vitamin D deficiency or insufficiency (1).

Research estimates that up to 42% of Americans have a vitamin D deficiency, but 82% of black Americans and 69% of Hispanic Americans are deficient (2), (3), (4).

And about 1/3 of people with a known vitamin D deficiency have no obvious risk factors (5).

So, how do you know if you have vitamin D deficiency?

Bones are Living Things

Vitamin D deficiency is diagnosed with a blood test to measure your levels of vitamin D.

Your doctor can order this test. Healthy blood levels of vitamin D are between 75 and 125nmol/l (6).

The table below gives you more information on what your vitamin D blood levels mean (7).


Vitamin D Blood Level

Too High




Insufficient/At Risk



Less than 50nmol/l

Risk Factors for Vitamin D Deficiency or Insufficiency

Vitamin D is not in its active form when it enters your body.

Your body has to convert it to the active form.

You can develop a vitamin D deficiency if you don’t eat enough vitamin D, your skin is not able to make vitamin D from the sun, your intestines are not able to absorb the vitamin D, or your liver and kidneys aren’t able to convert vitamin D to its active form.

The following are risk factors for developing vitamin D deficiency or insufficiency:


  • Diet – One risk factor is eating a diet low in vitamin D-rich foods.
  • Low sun exposure – Spending little time outside, wearing sunscreen, and wearing clothes that cover most of your skin puts you at risk.
  • Age – Vitamin D deficiency can affect you at any age, but as you age, your skin’s ability to make vitamin D goes down. About 50% of people 65 years and older have low vitamin D levels (8).
  • Skin color – If you have darker skin (more melanin), your skin does not make as much vitamin D from the sun.
  • Location – Living far south or far north of the equator means less UV ray exposure for your skin to make vitamin D.
  • Season – You are less likely to get enough vitamin D in the winter when you are outside less and wear more clothing.
  • Pollution – If you live in a city with a lot of pollution or smog, fewer UV rays will reach your skin to make vitamin D.
  • Diseases – If you have certain diseases, such as Crohn's disease or celiac disease, your intestines may not be able to absorb as much vitamin D.
  • Weight-loss surgery – If you have had bariatric (weight loss) surgery, you may also have a hard time absorbing vitamin D.
  • Medications – Some medications, such as laxatives, steroids, medicines to reduce cholesterol, medicines to control seizures, and weight-loss drugs, reduce your body‘s ability to absorb vitamin D (9).
  • Obesity – Research has found that people with obesity (body mass index [BMI] greater than 30) have lower vitamin D levels (10).

Signs & Symptoms of Vitamin D Deficiency

There are usually no signs or symptoms of vitamin D deficiency for many years, or the symptoms are nonspecific.

Eventually, vitamin D deficiency could result in osteopenia (weakened bones), osteoporosis (severely weakened or breaking bones), rickets (softening of bones in children), or osteomalacia (softening of bones in adults).

Some signs and symptoms that could be related to a vitamin D deficiency are below (11).

In children with vitamin D deficiency (12):

  • Incorrect growth pattern
  • Muscle weakness and pain
  • Bone pain
  • Joint deformities

In adults with vitamin D deficiency (13):

  • Fatigue
  • Bone pain, often throbbing and usually in the lower back, hips, or legs
  • Muscle weakness
  • Aching muscles
  • Muscle cramps
  • Mood changes, such as depression or anxiety
  • Frequent falls
  • Broken bones

How Much Vitamin D Do You Need?

The recommended dietary allowance (RDA) for vitamin D is 600 IU/day for ages 1 to 70 years and 800 IU/day for over 70 years (14).

Many healthcare professionals do not think the RDA is adequate.

The Endocrine Society recommends 600–1000 IU/day for ages 1 to 18 years and 1500–2000 IU/day for all adults (15).

After seeing the results of your blood levels, your doctor can recommend an appropriate dosage.

Ways to Get Vitamin D

1. Food – The following table shows high vitamin D foods and their amounts of vitamin D (16):


Vitamin D Blood Level

Amount of Vit D

Cod liver oil

1 Tbsp

1360 IU

Farmed rainbow trout

3 oz

645 IU

Sockeye salmon

3 oz

570 IU

White mushrooms

½ cup

366 IU

Vitamin D-fortified milk

1 cup

120 IU


1 large

44 IU

Beef liver

3 oz

42 IU

Canned light tuna in water

3 oz

40 IU

2. Sun exposure – While the sun is important for making vitamin D, too much of it can increase the risk for skin cancer, and sunscreen prevents your skin from making vitamin D. Being behind a window in your home or car also prevents the UV rays needed from reaching your skin.

How much sun exposure you need depends on several factors, such as your skin color, location, age, the season, the time of day, and the amount of pollution in the air. A general recommendation is 10 to 15 minutes 3 times a week to the face, arms, and hands (17).

    3. Supplements – If you’re not sure if you are getting enough vitamin D from your diet or sun exposure, talk to your doctor about a supplement. Vitamin D3 is the best choice for a vitamin D supplement because vitamin D3 raises vitamin D levels in the blood higher and keeps them there longer than vitamin D2 (18).

    Having a good intake of vitamin D can be dangerous if you don’t also get enough

    vitamin K2.

    Vitamin K2 helps calcium get into your bones instead of your arteries.

    A buildup of calcium in your blood vessels can contribute to heart disease.

    MK-7 is the most effective type of vitamin K2 (19).

    Supplements are not regulated by the Food and Drug Administration (FDA), so make sure you are buying high-quality supplements from a reputable source.

    Avoid buying supplements made outside of the U.S., which may not be regulated at all.