Vitamin d level 13

Vitamin D Deficiency: Causes, Signs and Symptoms, Risk Factors, and Consequences

Risk Factors for Vitamin D Deficiency

The following groups of people are at a higher risk for vitamin D deficiency.

People of color “People with darker skin are at an increased risk for vitamin D deficiency because they have more melanin in their skin,” Gorin explains. “This is a pigment that decreases the skin’s ability to procure vitamin D from sunlight.” (2) Only 5 percent of African Americans had sufficient vitamin D levels in their blood as of 2004, according to Endocrine Society. This compares with 30 percent of white people in the United States. (12)

People with kidney disease Vitamin D is converted into its active form in the kidneys, so if your kidneys are not functioning well, you could be taking in enough and absorbing enough, but your body can’t use it in the way it is needed. (12)

Individuals with liver disease Vitamin D deficiency has been associated with nonalcoholic fatty liver disease (NAFLD), in which extra fat cells build up in the liver, causing damage to the organ. (13) People with the disease are 26 percent more likely to be deficient in the nutrient than those who do not have the disease, according to a 2013 study published in Alimentary Pharmacology and Therapeutics. (14)

Individuals with various digestive disorders This includes inflammatory bowel disease (ulcerative colitis or Crohn’s disease), celiac disease, other various inflammatory or malabsorption disorders, and even cystic fibrosis. These conditions limit or even destroy the body’s ability to absorb vitamin D from the food that is eaten. (2)

Those with limited sunlight exposure The further away you are from the equator, the more at risk you are for vitamin D deficiency due to the angle of the sun’s rays. But the reality is that unless you are in an area where it is warm and sunny most of the year, you cannot count on the sun for your vitamin D year-round. More specifically, during the winter months, the sun’s rays are not at the right wavelength to cause vitamin D synthesis in the skin no matter how sunny it may be on a given day. (10)

Those who are obese The current statistics from the Centers for Disease Control and Prevention reveal that about 40 percent of adults and 18.5 percent of children in the United States are obese. (15,16) When you have excessive body fat, vitamin D gets trapped in your fat tissues instead of going into circulation for use. Obesity is defined as a body mass index (BMI) greater than 30, according to the National Heart, Lung, and Blood Institute. (17)

Exclusively breastfed infants Breast milk contains 20–40 IU/L of vitamin D, so exclusively breastfed infants need at least 400 IU of supplemental vitamin D. (18,19) Supplemental vitamin D can be found in liquid form at most grocers and pharmacies.

Those on self-imposed or medically restricted diets Whether you are eliminating certain food groups because you want or need to, the result is the same — risk of various nutrient deficiencies, including vitamin D deficiency, go up. (10)

People who are lactose intolerant This condition — an inability to digest the milk sugar lactose, leading to gas, bloating, and digestive issues — puts you at risk for vitamin D deficiency because you are less likely to consume fortified dairy products. The Mayo Clinic notes that with your doctor’s approval, you can safely drink lactose-free milk and you may be able to eat yogurt and cheese in small doses. There are dairy-free cheeses out there as well, or you can take a lactase enzyme supplement such as Lactaid before eating dairy to cover any digestive discomfort. Plant-based beverages that are fortified with vitamin D can also be beneficial. (2,21)

Those with an allergy to dairy When someone has a dairy allergy, they must eliminate all forms of dairy. The allergy involves an immune reaction to the protein in dairy — risks can range from skin rashes to life-threatening anaphylactic reactions. (22) Adults and children with a dairy allergy can benefit from taking a calcium and vitamin D supplement, as well as consuming plant-based beverages enriched or fortified with calcium and vitamin D.

Vegans Following a vegan diet, which involves eating only plant-based fare and no animal products, is linked to vitamin D deficiency. (2) That’s because it eliminates fortified dairy, eggs, and fatty fish as food sources for the nutrient. You may take vitamin D2 supplements (which are plant-based) or drink fortified nondairy beverages to make up the difference.

People on certain fad diets Some fad diets, such as paleo and Whole30, eliminate food groups that contain vitamin D. The paleo diet does not include dairy, though you can eat eggs and fish. Also, you can take supplements and plant-based beverages enriched and fortified with calcium and vitamin D. Meanwhile, Whole30 was created only to be a 30-day cleansing diet, but many people are doing it to lose and keep weight off beyond that period. Whole30 does not allow for any alternative version of dairy during the cleansing period because the diet calls for dairy-free, grain-free foods in their original form only. Consider taking a supplement while you are on Whole30.

And what about:

Pregnant and lactating women? Past studies suggested low vitamin D status in pregnancy can contribute to early deliveries and preeclampsia (or high blood pressure during pregnancy), pointing to possible benefits of supplementation. But in October 2019, the World Health Organization updated its guidelines to say that taking supplements is not recommended for pregnant women, noting that more research is needed about possible effects on preterm births. Moms-to-be are advised to get the nutrient from a balanced diet and sunlight exposure instead. For pregnant women who have been diagnosed with vitamin D deficiency only, taking no more than 200 IU in supplements is recommended. (23) As previously mentioned, the recommended daily allowance (RDA) is set at 600 IU overall — from all sources — for pregnant and lactating women.

Vitamin D Deficiency

Symptoms of vitamin D deficiency

What is vitamin D deficiency?

Vitamin D deficiency means that you do not have enough vitamin D in your body. Vitamin D is unique because your skin actually produces it by using sunlight. Fair-skinned individuals and those who are younger convert sunshine into vitamin D far better than those who are darker-skinned and over age 50.

Why is vitamin D so important?

Vitamin D is one of many vitamins our bodies need to stay healthy. This vitamin has many functions, including:

  • Keeping bones strong: Having healthy bones protects you from various conditions, including rickets. Rickets is a disorder that causes children to have bones that are weak and soft. It is caused by a lack of vitamin D in the body. You need vitamin D so that calcium and phosphorus can be used to build bones. In adults, having soft bones is a condition called osteomalacia.
  • Absorbing calcium: Vitamin D, along with calcium, helps build bones and keep bones strong and healthy. Weak bones can lead to osteoporosis, the loss of bone density, which can lead to fractures. Vitamin D, once either taken orally or from sunshine exposure is then converted to an active form of the vitamin. It is that active form that promotes optimal absorption of calcium from your diet.
  • Working with parathyroid glands: The parathyroid glands work minute to minute to balance the calcium in the blood by communicating with the kidneys, gut and skeleton. When there is sufficient calcium in the diet and sufficient active Vitamin D, dietary calcium is absorbed and put to good use throughout the body. If calcium intake is insufficient, or vitamin D is low, the parathyroid glands will ‘borrow’ calcium from the skeleton in order to keep the blood calcium in the normal range.

What are the health effects of vitamin D deficiency?

Getting enough vitamin D may also play a role in helping to keep you healthy by protecting against the following conditions and possibly helping to treat them. These conditions can include:

  • Heart disease and high blood pressure.
  • Diabetes.
  • Infections and immune system disorders.
  • Falls in older people.
  • Some types of cancer, such as colon, prostate and breast cancers.
  • Multiple sclerosis.

What are the sources of vitamin D?

You can get vitamin D in a variety of ways. These can include:

  • Being exposed to the sun. About 15-20 minutes three days per week is usually sufficient.
  • Through the foods you eat.
  • Through nutritional supplements.

What does sunlight have to do with getting enough vitamin D?

Vitamin D is produced when your skin is exposed to sunshine, or rather, the ultraviolet B (UV-B) radiation that the sun emits. The amount of vitamin D that your skin makes depends on such factors as:

  • The season: This factor depends a bit on where you live. In areas such as Cleveland, OH, the UV-B light does not reach the earth for six months out of the year due to the ozone layer and the zenith of the sun.
  • The time of day: The sun’s rays are most powerful between 10 a.m. and 3 p.m.
  • The amount of cloud cover and air pollution.
  • Where you live: Cities near the equator have higher ultraviolet (UV) light levels. It is the UV-B light in sunlight that causes your skin to make vitamin D.
  • The melanin content of your skin: Melanin is a brown-black pigment in the eyes, hair and skin. Melanin causes skin to tan. The darker your skin, the more sun exposure is needed in order to get sufficient vitamin D from the sun.

What does your diet have to do with getting enough vitamin D?

Vitamin D doesn’t occur naturally in many foods. That’s why certain foods have added vitamin D. In fact, newer food nutrition labels show the amount of vitamin D contained in a particular food item.

It may be difficult, especially for vegans or people who are lactose-intolerant, to get enough vitamin D from their diets, which is why some people may choose to take supplements. It is always important to eat a variety of healthy foods from all food groups. The vitamin content of various foods is shown in the following table.

Vitamin D content of various foods

Food Vitamin D content in International Units (IUs) per serving
Cod liver oil, 1 tablespoon 1360
Swordfish, cooked, 3 ounces 566
Salmon (sockeye) cooked, 3 ounces 447
Tuna, canned in water, drained, 3 ounces 154
Orange juice fortified with vitamin D, 1 cup 137
Milk, vitamin-fortified, 1 cup 115-124
Yogurt, fortified with 20% of the daily value of vitamin D, 6 ounces 80
Sardines, canned in oil, drained, 2 sardines 46
Liver, beef, cooked, 3 ounces 42
Egg yolk, 1 large 41
Cereal, fortified with 10% of the daily value of vitamin D, 1 cup 40
Cheese, Swiss, 1 ounce 6

Source: Vitamin D. Health Professionals. Dietary Supplement Fact Sheet. National Institutes of Health. Office of Dietary Supplements. August 7, 2019.

It is important to check product labels, as the amount of added vitamin D varies when it is artificially added to products such as orange juice, yogurt and margarine.

How much vitamin D do you need?

In healthy people, the amount of vitamin D needed per day varies by age. The chart below shows the often-cited recommendations of the Institute of Medicine, now the Health and Medicine Division of the National Academies of Sciences, Engineering, and Medicine. It is important to know that these are general recommendations. If your doctor is checking your blood levels, he or she might recommend higher or lower doses based on your individual needs.

If you have osteoporosis, your doctor might suggest a blood test of your vitamin D levels. The amount of vitamin D supplement can be customized for each person, based on the results. For many older patients, a vitamin D supplement containing anywhere between 800 to 2000 IUs daily, which can be obtained without a prescription, can be both safe and beneficial. It is important to speak with your doctor about your individual needs.

People by age Recommended dietary allowance (IU/day) Upper level intake (IU/day)
Infants 0-6 months* 400 1,000
Infants 6-12 months* 400 1,500
Children 1-3 years old 600 2,500
Children 4-8 years old 600 3,000
People 9-70 years old 600 4,000
People over 70 years old 800 4,000
Females 14-50 years old, pregnant/lactating 600 4,000

*refers to adequate intake vs recommended dietary allowance of the other age groups.

What causes vitamin D deficiency?

Vitamin D deficiency can be caused by specific medical conditions, such as:

  • Cystic fibrosis, Crohn’s disease, and celiac disease: These diseases do not allow the intestines to absorb enough vitamin D through supplements.
  • Weight loss surgeries. Weight loss surgeries that reduce the size of the stomach and/or bypasses part of the small intestines make it very difficult to consume sufficient quantities of certain nutrients, vitamins, and minerals. These individuals need to be carefully monitored by their doctors and need to continue to take vitamin D and other supplements throughout their lives.
  • Obesity: A body mass index greater than 30 is associated with lower vitamin D levels. Fat cells keep vitamin D isolated so that it is not released. Vitamin D deficiency is more likely in obese people. Obesity often makes it necessary to take larger doses of vitamin D supplements in order to reach and maintain normal D levels.
  • Kidney and liver diseases: These diseases reduce the amount of an enzyme needed to change vitamin D to a form that is used in the body. Lack of this enzyme leads to an inadequate level of active vitamin D in the body.

What other factors can lead to vitamin D deficiency?

  • Age: The skin’s ability to make vitamin D lessens with age.
  • Mobility: People who are homebound or are rarely outside (for example, people in nursing homes and other facilities) are not able to use sun exposure as a source of vitamin D.
  • Skin color: Dark-colored skin is less able to make vitamin D than fair-colored skin.
  • Human breast milk: A woman’s breast milk only contains a small amount of vitamin D. Often infant formulas also only include a small amount of D also. Therefore infants are at risk of not receiving enough vitamin D. This is especially true for infants who are only fed breast milk.

Can medications cause a vitamin D deficiency?

Yes. Vitamin D levels can be lowered by certain medications. These include:

Always tell your doctor about the drugs you take and any vitamin D supplements or other supplements or herbs/alternative health products that you take.

What are the signs and symptoms of vitamin D deficiency?

Severe lack of vitamin D causes rickets, which shows up in children as incorrect growth patterns, weakness in muscles, pain in bones and deformities in joints. This is very rare. However, children who are deficient in vitamin D can also have muscle weakness or sore and painful muscles.

Lack of vitamin D is not quite as obvious in adults. Signs and symptoms might include:

  • Fatigue.
  • Bone pain.
  • Muscle weakness, muscle aches, or muscle cramps.
  • Mood changes, like depression.

Share Facebook Twitter LinkedIn Email Get useful, helpful and relevant health + wellness information enews

Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy

Vitamin D Deficiency

Vitamin D deficiency means that you are not getting enough vitamin D to stay healthy.

Why do I need vitamin D and how do I get it?

Vitamin D helps your body absorb calcium. Calcium is one of the main building blocks of bone. Vitamin D also has a role in your nervous, muscle, and immune systems.

You can get vitamin D in three ways: through your skin, from your diet, and from supplements. Your body forms vitamin D naturally after exposure to sunlight. But too much sun exposure can lead to skin aging and skin cancer, so many people try to get their vitamin D from other sources.

How much vitamin D do I need?

The amount of vitamin D you need each day depends on your age. The recommended amounts, in international units (IU), are

  • Birth to 12 months: 400 IU
  • Children 1-13 years: 600 IU
  • Teens 14-18 years: 600 IU
  • Adults 19-70 years: 600 IU
  • Adults 71 years and older: 800 IU
  • Pregnant and breastfeeding women: 600 IU

People at high risk of vitamin D deficiency may need more. Check with your health care provider about how much you need.

You can become deficient in vitamin D for different reasons:

  • You don’t get enough vitamin D in your diet
  • You don’t absorb enough vitamin D from food (a malabsorption problem)
  • You don’t get enough exposure to sunlight.
  • Your liver or kidneys cannot convert vitamin D to its active form in the body.
  • You take medicines that interfere with your body’s ability to convert or absorb vitamin D

Who is at risk of vitamin D deficiency?

Some people are at higher risk of vitamin D deficiency:

  • Breastfed infants, because human milk is a poor source of vitamin D. If you are breastfeeding, give your infant a supplement of 400 IU of vitamin D every day.
  • Older adults, because your skin doesn’t make vitamin D when exposed to sunlight as efficiently as when you were young, and your kidneys are less able to convert vitamin D to its active form.
  • People with dark skin, which has less ability to produce vitamin D from the sun.
  • People with disorders such as Crohn’s disease or celiac disease who don’t handle fat properly, because vitamin D needs fat to be absorbed.
  • People who have obesity, because their body fat binds to some vitamin D and prevents it from getting into the blood.
  • People who have had gastric bypass surgery
  • People with osteoporosis
  • People with chronic kidney or liver disease.
  • People with hyperparathyroidism (too much of a hormone that controls the body’s calcium level)
  • People with sarcoidosis, tuberculosis, histoplasmosis, or other granulomatous disease (disease with granulomas, collections of cells caused by chronic inflammation)
  • People with some lymphomas, a type of cancer.
  • People who take medicines that affect vitamin D metabolism, such as cholestyramine (a cholesterol drug), anti-seizure drugs, glucocorticoids, antifungal drugs, and HIV/AIDS medicines.

Talk with your health care provider if you are at risk for vitamin D deficiency. There is a blood test which can measure how much vitamin D is in your body.

What problems does vitamin D deficiency cause?

Vitamin D deficiency can lead to a loss of bone density, which can contribute to osteoporosis and fractures (broken bones).

Severe vitamin D deficiency can also lead to other diseases. In children, it can cause rickets. Rickets is a rare disease that causes the bones to become soft and bend. African American infants and children are at higher risk of getting rickets. In adults, severe vitamin D deficiency leads to osteomalacia. Osteomalacia causes weak bones, bone pain, and muscle weakness.

Researchers are studying vitamin D for its possible connections to several medical conditions, including diabetes, high blood pressure, cancer, and autoimmune conditions such as multiple sclerosis. They need to do more research before they can understand the effects of vitamin D on these conditions.

How can I get more vitamin D?

There are a few foods that naturally have some vitamin D:

  • Fatty fish such as salmon, tuna, and mackerel
  • Beef liver
  • Cheese
  • Mushrooms
  • Egg yolks

You can also get vitamin D from fortified foods. You can check the food labels to find out whether a food has vitamin D. Foods that often have added vitamin D include

  • Milk
  • Breakfast cereals
  • Orange juice
  • Other dairy products, such as yogurt
  • Soy drinks

Vitamin D is in many multivitamins. There are also vitamin D supplements, both in pills and a liquid for babies.

If you have vitamin D deficiency, the treatment is with supplements. Check with your health care provider about how much you need to take, how often you need to take it, and how long you need to take it.

Can too much vitamin D be harmful?

Getting too much vitamin D (known as vitamin D toxicity) can be harmful. Signs of toxicity include nausea, vomiting, poor appetite, constipation, weakness, and weight loss. Excess vitamin D can also damage the kidneys. Too much vitamin D also raises the level of calcium in your blood. High levels of blood calcium (hypercalcemia) can cause confusion, disorientation, and problems with heart rhythm.

Most cases of vitamin D toxicity happen when someone overuses vitamin D supplements. Excessive sun exposure doesn’t cause vitamin D poisoning because the body limits the amount of this vitamin it produces.

Low vitamin D levels linked to increased multiple sclerosis risk

“Lack of vitamin D may cause multiple sclerosis, study finds,” reports the Guardian. A large study found people genetically programmed to have lower vitamin D levels are at an increased risk of multiple sclerosis (MS).

MS is a condition where the immune system attacks the coating of nerves in the brain and spinal cord, leading to symptoms such as vision loss, fatigue, and difficulties with balance and co-ordination.

Our body makes vitamin D under the skin in reaction to sunlight. We also get small amounts of the vitamin from our diet in foods such as eggs and oily fish.

A link between vitamin D deficiency and an increased risk of MS has long been suspected, as the condition is more common in areas of the world with less sunlight, such as northern Scotland. But it has been difficult to prove cause and effect because other factors may be involved.

This study used a genetic approach believed to be less susceptible to the problem of confounding – where other factors influence the results.

The researchers learned four genetic variants influence vitamin D levels found in the blood. People can have different combinations of these genetic variations. They found people with a combination of the genetic variations giving them lower levels of vitamin D had double the risk of MS.

But what the study does not tell us is whether MS could be prevented in those at higher risk by increasing their vitamin D levels through taking supplements or other methods.

Find out more about the “sunshine vitamin” in our special report on the health claims made about vitamin D.

Where did the story come from?

The study was carried out by researchers from McGill University and the Jewish General Hospital in Canada; the University of Bristol and King’s College London in the UK; and Massachusetts General Hospital and Harvard Medical School in the US.

It was funded by the Canadian Institute of Health Research, The Fonds de la Recherche en Santé Québec, the Lady Davis Institute, the Jewish General Hospital, and the Canadian Diabetes Association.

The study was published in the peer-reviewed journal PLOS Medicine on an open-access basis, so it is free to read online.

The UK media reported the story accurately, and many reports included reactions to the research findings from experts such as Professor Danny Altmann, an immunologist at Imperial College London.

Professor Altmann said: “While it may be too much to expect therapeutic vitamin D to treat or reverse ongoing MS, this paper will add to the weight of argument for routine vitamin D supplementation of foodstuffs as a broad preventative public health measure.”

What kind of research was this?

This genetic study looked at whether there is an association between genetically influenced levels of vitamin D and the risk of MS.

Previous observational studies found an association between lower levels of vitamin D and MS risk. In particular, MS is more common in people living in geographical areas with reduced sunlight – vitamin D levels are increased by exposing the skin to the sun.

But these studies were unable to prove cause and effect. Questions remain, such as whether the low vitamin D caused MS, or whether vitamin D levels go down in people with MS because they have less exposure to the sun as a result of their condition.

Exposure to sunlight is just one way to increase our vitamin D levels. There is also a genetic component that will have a lifetime influence. This study specifically looked for genetic variations linked to vitamin D levels and whether these genetic variations were also associated with MS risk.

This type of study is called a Mendelian randomisation study because these genetic variations are inherited randomly (each parent will have two copies of each, which one we inherit is random). The term is named after Gregor Mendel, a pioneering 19th century scientist, widely regarded as the father of modern genetics.

The study design means confounding by other factors is not a problem.The researchers in the study took additional steps to be sure this was the case.

What did the research involve?

The researchers identified genetic variations associated with vitamin D levels using data from the SUNLIGHT study. The Study of Underlying Genetic Determinants of Vitamin D and Highly Related Traits included blood samples from 33,996 people.

They identified four genetic variations associated with lower vitamin D levels. These were close to four genes that create products that have an effect on the level of vitamin D:

  • a protein that binds to vitamin D and carries it in the blood to target organs
  • an enzyme involved in making vitamin D in the body in response to sunlight
  • an enzyme that activates production of vitamin D
  • an enzyme that inactivates vitamin D

They then used data from the Canadian Multicentre Osteoporosis study (CaMos) of 2,347 people to confirm the effect of these four genetic variants on vitamin D levels.

The researchers used the results to investigate the risk of MS depending on the genetic variations a person carried and their genetically determined lifetime level of vitamin D using data from two studies:

  • the International Multiple Sclerosis Genetics Consortium (IMSGC), which has data from 14,498 people with MS and 24,091 healthy controls, all of European descent
  • the IMSGC/Wellcome Trust Case Control Consortium 2 (IMSGC/WTCCC2) study, which has data from 9,772 people with MS and 6,332 controls

The researchers took the following factors into account when analysing the results:

  • age
  • sex
  • body mass index (BMI)
  • time of year the blood sample was taken
  • ethnicity

What were the basic results?

The four genetic variants associated with reduced vitamin D levels were also associated with an increased risk of MS, with three showing stronger links than the fourth. Each variant was only associated with a relatively small increase in the odds of MS (odds ratio of 1.04 to 1.11).

Each genetically determined standard deviation decrease in vitamin D levels doubled the risk of MS (OR 2.0, 95% confidence interval 1.7 to 2.5).

How did the researchers interpret the results?

The researchers concluded: “Genetically lowered 25OHD level is associated with an increase in the risk of MS in people of European descent.”

They said that: “These findings provide rationale for further investigating the potential therapeutic benefits of vitamin D supplementation in preventing the onset and progression of MS.”

Conclusion

This study found people with a genetic susceptibility to having lower levels of vitamin D have an increased risk of developing MS.

What the study does not tell us is whether MS could be prevented in those at higher risk by taking steps to increase their vitamin D levels. The results also may not apply to people who are not of European descent.

Studies in healthy children and adults are now underway to explore this area. This study does not show what effect taking supplementary vitamin D would have in people who already have MS.

Previous research into vitamin D being used as a treatment for MS and to prevent relapse has been inconclusive because of small study sizes and poor methodology, so large randomised controlled trials are required.

Nevertheless, this piece of research adds to the growing picture that low levels of vitamin D appear to play some part in the development of MS.

You can usually get enough vitamin D through modest exposure of the skin to sunlight (no suntanning required) and a healthy diet that includes oily fish, eggs and foods fortified with vitamin D.

Some people may require vitamin D supplements, such as people aged 65 and over or those not exposed to much sunlight. The NHS suggests that if you take vitamin D supplements, you should not take more than 25 micrograms (0.025mg) a day as it could be harmful.

Find out more about vitamin D.

Analysis by Bazian
Edited by NHS Website

Links to the headlines

Lack of vitamin D may cause multiple sclerosis, study finds

The Guardian, 25 August 2015

Low vitamin-D genes linked to MS

BBC News, 26 August 2015

Why sunlight could protect against multiple sclerosis

The Daily Telegraph, 25 August 2015

Links to the science

Mokry LE, Ross S, Ahmad OS, et al.

Vitamin D and Risk of Multiple Sclerosis: A Mendelian Randomization Study

PLOS Medicine. Published online August 25 2015

  1. 1. Wood BH, Bilclough JA, Bowron A, Walker RW. Incidence and prediction of falls in parkinson’s disease: A prospective multidisciplinary study. Journal of Neurology, Neurosurgery & Psychiatry. 2002;72(6):721–725.
    • View Article
    • Google Scholar
  2. 2. Bloem BR, Hausdorff JM, Visser JE, Giladi N. Falls and freezing of gait in parkinson’s disease: A review of two interconnected, episodic phenomena. Movement Disorders. 2004;19(8):871–884. pmid:15300651
    • View Article
    • PubMed/NCBI
    • Google Scholar
  3. 3. Bloem BR, van Vugt JP, Beckley DJ. Postural instability and falls in parkinson’s disease. Adv Neurol. 2001;87:209–223. pmid:11347224
    • View Article
    • PubMed/NCBI
    • Google Scholar
  4. 4. Stel VS, Smit JH, Pluijm SM, Lips P. Consequences of falling in older men and women and risk factors for health service use and functional decline. Age & Ageing. 2004;33(1):58–65.
    • View Article
    • Google Scholar
  5. 5. Forsaa EB, Larsen JP, Wentzel-Larsen T, Herlofson K, Alves G. Predictors and course of health-related quality of life in parkinson’s disease. Movement Disorders. 2008;23(10):1420–1427. pmid:18512757
    • View Article
    • PubMed/NCBI
    • Google Scholar
  6. 6. Gagnon N, Flint AJ, Naglie G, Devins GM. Affective correlates of fear of falling in elderly persons. American Journal of Geriatric Psychiatry. 2005;13(1):7–14. pmid:15653935
    • View Article
    • PubMed/NCBI
    • Google Scholar
  7. 7. van Haastregt JC, Zijlstra GA, van Rossum E, van Eijk JT, Kempen GI. Feelings of anxiety and symptoms of depression in community-living older persons who avoid activity for fear of falling. American Journal of Geriatric Psychiatry. 2008;16(3):186–193. pmid:18310549
    • View Article
    • PubMed/NCBI
    • Google Scholar
  8. 8. Peterson AL, Fink HA, Quinn J, Barret-Connor E, Shikany J, Orwoll E. Vitamin D levels in men with parkinson’s disease. Mov Disord. 2008;23(11):1635.
    • View Article
    • Google Scholar
  9. 9. Evatt ML, Delong MR, Khazai N, Rosen A, Triche S, Tangpricha V. Prevalence of vitamin d insufficiency in patients with parkinson disease and alzheimer disease. Arch Neurol. 2008;65(10):1348–1352. pmid:18852350
    • View Article
    • PubMed/NCBI
    • Google Scholar
  10. 10. Sato Y, Kikuyama M, Oizumi K. High prevalence of vitamin D deficiency and reduced bone mass in parkinson’s disease. Neurology. 1997;49(5):1273–1278. pmid:9371907
    • View Article
    • PubMed/NCBI
    • Google Scholar
  11. 11. Gallagher JC, Fowler SE, Detter JR, Sherman SS. Combination treatment with estrogen and calcitriol in the prevention of age-related bone loss. Journal of Clinical Endocrinology & Metabolism. 2001;86(8):3618–3628.
    • View Article
    • Google Scholar
  12. 12. Grant AM, Avenell A, Campbell MK, et al. Oral vitamin D3 and calcium for secondary prevention of low-trauma fractures in elderly people (randomised evaluation of calcium or vitamin D, RECORD): A randomised placebo-controlled trial. Lancet. 2005;365(9471):1621–1628. pmid:15885294
    • View Article
    • PubMed/NCBI
    • Google Scholar
  13. 13. Trivedi DP, Doll R, Khaw KT. Effect of four monthly oral vitamin D3 (cholecalciferol) supplementation on fractures and mortality in men and women living in the community: Randomised double blind controlled trial. BMJ. 2003;326(7387):469. pmid:12609940
    • View Article
    • PubMed/NCBI
    • Google Scholar
  14. 14. Bischoff-Ferrari HA, Dawson-Hughes B, Willett WC, et al. Effect of vitamin D on falls: A meta-analysis.. JAMA. 2004;291(16):1999–2006. pmid:15113819
    • View Article
    • PubMed/NCBI
    • Google Scholar
  15. 15. Jackson C, Gaugris S, Sen SS, Hosking D. The effect of cholecalciferol (vitamin D3) on the risk of fall and fracture: A meta-analysis. QJM. 2007;100(4):185–192. pmid:17308327
    • View Article
    • PubMed/NCBI
    • Google Scholar
  16. 16. Latham NK, Anderson CS, Reid IR. Effects of vitamin D supplementation on strength, physical performance, and falls in older persons: A systematic review. J Am Geriatr Soc. 2003;51(9):1219–1226. pmid:12919233
    • View Article
    • PubMed/NCBI
    • Google Scholar
  17. 17. O’Donnell S, Moher D, Thomas K, Hanley DA, Cranney A. Systematic review of the benefits and harms of calcitriol and alfacalcidol for fractures and falls. Journal of Bone & Mineral Metabolism. 2008;26(6):531–542.
    • View Article
    • Google Scholar
  18. 18. Richy F, Dukas L, Schacht E. Differential effects of D-hormone analogs and native vitamin D on the risk of falls: A comparative meta-analysis. Calcif Tissue Int. 2008;82(2):102–107. pmid:18239843
    • View Article
    • PubMed/NCBI
    • Google Scholar
  19. 19. Bischoff-Ferrari HA, Willett WC, Wong JB, et al. Prevention of nonvertebral fractures with oral vitamin D and dose dependency: A meta-analysis of randomized controlled trials. Arch Intern Med. 2009;169(6):551–561. pmid:19307517
    • View Article
    • PubMed/NCBI
    • Google Scholar
  20. 20. Pfeifer M, Begerow B, Minne HW, Suppan K, Fahrleitner-Pammer A, Dobnig H. Effects of a long-term vitamin D and calcium supplementation on falls and parameters of muscle function in community-dwelling older individuals. Osteoporosis Int. 2009;20(2):315–322.
    • View Article
    • Google Scholar
  21. 21. Pfeifer M, Begerow B, Minne HW, Abrams C, Nachtigall D, Hansen C. Effects of a short-term vitamin D and calcium supplementation on body sway and secondary hyperparathyroidism in elderly women. Journal of Bone & Mineral Research. 2000;15(6):1113–1118.
    • View Article
    • Google Scholar
  22. 22. Gallagher JC, Vitamin D and falls–the dosage conundrum. Nature Reviews Endocrinology. 2016; 12(11):680–684. pmid:27494391
    • View Article
    • PubMed/NCBI
    • Google Scholar
  23. 23. Smith H, Effects of annual intramuscular vitamin D on fracture risk in elderly men and women—a population-based, randomized, double-blind, placebo-controlled trial. Rheumatology. 2007; 46: 1852–1857. pmid:17998225
    • View Article
    • PubMed/NCBI
    • Google Scholar
  24. 24. Sanders KM. Annual high-dose oral vitamin D falls and fractures in older women: a randomized controlled trial. JAMA. 2010; 303:1815–1822. pmid:20460620
    • View Article
    • PubMed/NCBI
    • Google Scholar
  25. 25. Bischoff-Ferrrari HA, Monthly high-dose vitamin D treatment for the prevention of functional decline: A randomized clinical trial. JAMA Internal Medicine. 2016; 176: 175–183. pmid:26747333
    • View Article
    • PubMed/NCBI
    • Google Scholar
  26. 26. Smith LM, Gallagher JC, Suiter C. Medium doses of daily vitamin D decrease falls and higher doses of daily vitamin D3 increase falls: A randomized clinical trial. J Steroid Biochem Mol Biol. 2017;173:317–322. pmid:28323044
    • View Article
    • PubMed/NCBI
    • Google Scholar
  27. 27. Bischoff-Ferrari HA, Conzelmann M, Stahelin HB, et al. Is fall prevention by vitamin D mediated by a change in postural or dynamic balance?. Osteoporosis Int. 2006;17(5):656–663.
    • View Article
    • Google Scholar
  28. 28. Bunout D, Barrera G, Leiva L, et al. Effects of vitamin D supplementation and exercise training on physical performance in chilean vitamin D deficient elderly subjects. Exp Gerontol. 2006;41(8):746–752. pmid:16797903
    • View Article
    • PubMed/NCBI
    • Google Scholar
  29. 29. Eyles DW, Smith S, Kinobe R, Hewison M, McGrath JJ. Distribution of the vitamin D receptor and 1 alpha-hydroxylase in human brain. J Chem Neuroanat. 2005;29(1):21–30. pmid:15589699
    • View Article
    • PubMed/NCBI
    • Google Scholar
  30. 30. Peterson AL, Mancini M, Horak FB. The relationship between balance control and vitamin D in parkinson’s disease-a pilot study. Mov Disord. 2013;28(8):1133–1137. pmid:23554003
    • View Article
    • PubMed/NCBI
    • Google Scholar
  31. 31. Buatois S, Gueguen R, Gauchard GC, Benetos A, Perrin PP. Posturography and risk of recurrent falls in healthy non-institutionalized persons aged over 65. Gerontology. 2006;52(6):345–352. pmid:16905886
    • View Article
    • PubMed/NCBI
    • Google Scholar
  32. 32. Bischoff-Ferrari HA, Dawson-Hughes B, Staehelin HB, et al. Fall prevention with supplemental and active forms of vitamin D: A meta-analysis of randomised controlled trials. BMJ. 2009;339:b3692. pmid:19797342
    • View Article
    • PubMed/NCBI
    • Google Scholar
  33. 33. Bischoff-Ferrari HA, Dietrich T, Orav EJ, et al. Higher 25-hydroxyvitamin D concentrations are associated with better lower-extremity function in both active and inactive persons aged > or = 60 y. Am J Clin Nutr. 2004;80(3):752–758. pmid:15321818
    • View Article
    • PubMed/NCBI
    • Google Scholar
  34. 34. Holick MF. Vitamin D deficiency. N Engl J Med. 2007;357(3):266–281. pmid:17634462
    • View Article
    • PubMed/NCBI
    • Google Scholar
  35. 35. NeuroCom International I. Balance manager system—clinical interpretation guide—computerized posturography.
  36. 36. Drouin JM, Valovich-mcLeod TC, Shultz SJ, Gansneder BM, Perrin DH. Reliability and validity of the biodex system 3 pro isokinetic dynamometer velocity, torque and position measurements. Eur J Appl Physiol. 2004;91(1):22–29. pmid:14508689
    • View Article
    • PubMed/NCBI
    • Google Scholar
  37. 37. Buchner DM, Hornbrook MC, Kutner NG, et al. Development of the common data base for the FICSIT trials. J Am Geriatr Soc. 1993;41(3):297–308. pmid:8440854
    • View Article
    • PubMed/NCBI
    • Google Scholar
  38. 38. Ryan JW, Dinkel JL, Petrucci K. Near falls incidence. A study of older adults in the community. J Gerontol Nurs. 1993;19(12):23–28. pmid:8301024
    • View Article
    • PubMed/NCBI
    • Google Scholar
  39. 39. Peto V, Jenkinson C, Fitzpatrick R. PDQ-39: A review of the development, validation and application of a parkinson’s disease quality of life questionnaire and its associated measures. J Neurol. 1998;245(Suppl 1):S10–4.
    • View Article
    • Google Scholar
  40. 40. Hagell P, Whalley D, McKenna SP, Lindvall O. Health status measurement in parkinson’s disease: Validity of the PDQ-39 and nottingham health profile. Movement Disorders. 2003;18(7):773–783. pmid:12815656
    • View Article
    • PubMed/NCBI
    • Google Scholar
  41. 41. Powell LE, Myers AM. The activities-specific balance confidence (ABC) scale. Journals of Gerontology Series A-Biological Sciences & Medical Sciences. 1995;50A(1):M28–34.
    • View Article
    • Google Scholar
  42. 42. Fahn S, Marsden CD, Goldstein M, Calne CD, eds. Recent deveoplments in parkinson’s disease. Florham Park, NJ: Macmillan Healthcare Information; 1987; No. 2.
  43. 43. Lam V, Takechi R, Pallabage-Gamarallage M, Giles C, Mamao JCL. The Vitamin D, Ionized Calcium and Parathyroid Hormone Axis of Cerebral Capillary Function: Therapeutic Considerations for Vascular-Based Neurodegenerative Disorders. PLOS ONE. 2015 Apr 13; 10(4).
    • View Article
    • Google Scholar

About the author

Leave a Reply

Your email address will not be published. Required fields are marked *