Depression

Vitamin D Deficiency: Symptoms, signs, and side effects—plus vitamin D sources, vitamin D recommendations, and vitamin D benefits

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By Cindy Foley • August 20, 2018

TABLE OF CONTENTS

Introduction
I. What Is Vitamin D?
II. Do I Need a Vitamin D Blood Test?
III. Vitamin D Sources: Sunshine, Supplements, and Food
IV. Vitamin D Research: What Studies Tell Us

INTRODUCTION

What causes vitamin D deficiency? In this free guide from the editors of University Health News, you’ll learn about:
• Vitamin D’s critical role in your body
• Vitamin D deficiency symptoms
• The best sources of vitamin D
• Vitamin D warnings
• Recommendations for vitamin D intake

If you’re confused about whether or not you should take a vitamin D supplement, you’re not alone. Medical opinion is divided on the subject. While research backing the importance of vitamin D is coming at warp speed, there are credible sources available that are applying the brakes.

For instance, an editorial in the Journal of the American Medical Association in 2015 recommended that physicians “avoid over-screening and over-prescribing supplemental vitamin D,” citing the “lack of convincing evidence for non-bone benefits of vitamin D.” The editorial further suggested that patients avoid taking more than the current Recommended Dietary Allowance (RDA) for vitamin D of 600 IU (international units) per day through age 70, and 800 IU for those age 71 and older.

Meanwhile, researchers like Dr. Michael Holick, a prominent expert on vitamin D at Boston University Medical Center, says that every cell in the body has a receptor for vitamin D.

The bottom line? Consumers can rest easy knowing that, while disagreement continues about what constitutes an optimal level of vitamin D in our blood, experts do agree that vitamin D’s role in our body’s health is substantial.

Vitamin D is well established for its role in bone health; it’s important in preventing osteopenia, osteoporosis, and rickets. The reason many products today are sold as “fortified” or “vitamin D added” is because of widespread rickets in children prior to the 1930s, which was traced to a lack of vitamin D.

Rickets is a disease where bones are soft and weak. The adult form is called osteomalacia and can often be traced to disease, like cancer or liver disease, that causes an abnormality in the metabolism of vitamin D and can lead to hyperparathyroidism. (Hyperparathyroidism is a disorder in which the parathyroid glands in your neck produce too much parathyroid hormone, or PTH. The parathyroid glands help control calcium use and removal by the body.)

Research also strongly supports vitamin D’s role as an anti-inflammatory, as an immune-system booster, and for muscle strength. The latest studies show low vitamin D as a risk factor for a host of diseases, including cancer, hypertension, depression, fatigue, diabetes, dementia, and incontinence, adding credence to Dr. Holick’s assertion that vitamin D has an impact on every cell in our bodies.

“Any improvement in vitamin D status,” according to a 2012 study by Boston University researchers, “will significantly affect expression of genes that have a wide variety of biologic functions of more than 160 pathways linked to cancer, autoimmune disorders, and cardiovascular disease.”

In addition, as we age, our kidneys become less efficient in converting vitamin D to its active form (calcitriol), which can lead to deficiency.
Throughout this report, we’ll explore how vitamin D works in our body and learn the best ways to ensure adequate levels. We’ll discuss the controversy about optimal vitamin D levels and who should be tested for low vitamin D. Finally, we’ll share studies that support the many well-researched benefits of vitamin D.

1. What Is Vitamin D?

Vitamin D’s primary job is to ensure that your body absorbs the calcium it needs from foods and supplements. Once vitamin D has been ingested or absorbed through your skin, the liver and kidneys convert it to hormonal forms that ensure a proper blood level of calcium and phosphorus for bone health. Without adequate vitamin D, the body obtains calcium directly from the bones, leading to weakened bones, osteoporosis, and rickets.

According to the Endocrine Society, vitamin D is a prohormone, a substance the body makes into a hormone. Our bodies convert vitamin D to several different forms:
• Calcidiol, or 25-Hydroxyvitamin D (25 (OH)D). The major circulating form of vitamin D. (Blood tests measure this substance to determine whether vitamin D levels are low.)
• Calcitriol, or 1,25-dihydroxyvitamin D. The active hormone form of vitamin D.
• Calciferol or Ergocalciferol (vitamin D2). A form of vitamin D produced by plant life, such as that found in almond milk.
• Cholecalciferol (vitamin D3). An antirachitic (curing/preventing rickets) form of vitamin D.

Vitamin D is a fat-soluble vitamin. Excesses of fat-soluble vitamins remain in our bodies and can reach toxic levels. Vitamins A, E, and K are also fat-soluble. Other vitamins, such as the Bs and vitamin C, are water-soluble, which means excesses are excreted.

It’s important to understand that actual vitamin D excesses in the body are rare. The most common exception occurs when people take excessive amounts of a vitamin D supplement.

The Vitamin D Council says that intakes of more than 10,000 IUs daily for three months or more can lead to a toxic level of vitamin D. Result? The liver takes vitamin D and produces an excess of the chemical calcidiol or 25 (OH)D. (It is, also known as calcifidiol.) When an excess of this chemical gets in our blood, it increases the amount of calcium in our blood, leading to hypercalcemia.

Symptoms of hypercalcemia include:
• Loss of appetite
• Excess thirst
• Frequent urination
• Changes in bowel habits
• Abdominal pain
• Confusion
• Weakness

What Constitutes Low Vitamin D?
While too much vitamin D is rare but dangerous to our health, low vitamin D is common and worrisome. Research has shown a link between vitamin D deficiency and your risk of developing:
• Asthma
• Cancer
• Cardiovascular disease
• Depression
• Diabetes
• Incontinence
• Multiple sclerosis
• Periodontal disease
• Risk of getting a cold or the flu
• Tuberculosis
• Weakened bones and muscles

A “link” means that a statistically significant number of people with these conditions also show low blood levels of vitamin D. It doesn’t mean that suboptimal vitamin D levels can cause these problems, or that a lack of vitamin D won’t cause these problems—nor does it mean that increasing vitamin D will cure these problems. The link here is simply a statistical connection between low vitamin D and the list of conditions.

The Endocrine Society contends that chronic low vitamin D may raise the risk of developing some diseases. However, the Society does not state there is a cause-and-effect link, nor do they say that adding vitamin D will lower your risk of developing disease. More research is needed to make such determinations.

Making Sense of Vitamin D Levels
One common criticism of vitamin D studies is the definition of “low” vitamin D. There’s variation among experts as to what blood levels define deficiency and what levels are an insufficiency, because there’s no universally set “optimal” level of vitamin D.

• The International Osteoporosis Organization and the U.S. Endocrine Society both say optimal levels are at least 30 nanograms per milliliter (ng/mL). Dr. Holick believes blood levels of 25 (OH)D should be between 30 and 100 ng/mL to avoid long-term negative health consequences and between 40 and 60 ng/mL for optimal health.

• Most everyone agrees that the definition of a deficiency is a level at which diseases such as rickets can occur. A vitamin D blood level below 10 ng/mL is considered deficient by all standards and requires supplementation.

From there, it gets a little murky. An insufficiency (also called a “potential deficiency”) means you may be at risk for health complications due to low vitamin D. The Endocrine Society states that chronic low vitamin D may raise the risk of developing some diseases, acknowledging that a link between vitamin D and many diseases has been found. However, the Society doesn’t state there is a cause-and-effect link, nor does it say that adding vitamin D will lower your risk of developing disease.

The Centers for Disease Control and Prevention (CDC) has no common definition for adequate vitamin D status. The CDC does, however, allow that some scientists have suggested that the criteria used to define adequate status should be revised upward and that concentrations between 20 ng/mL and 32 ng/mL have been defined as sufficient.

If your blood test reveals a level between 20 and 30 mg/mL, the Vitamin D Council would call this deficient. Others call the level insufficient, meaning you need more vitamin D but aren’t at a serious health risk.

So what’s the right vitamin D level? Your health, age, and lifestyle may affect what your ideal level should be; your physician will point you in the right direction. But ultimately, the most commonly accepted range for “adequate” vitamin D levels is 30 to 39 ng/mL, while the most common recommendation for an “optimal” range is 40 to 49 ng/mL.

Why is our vitamin D level—and how it’s defined—important? A 2006 study in the American Journal of Public Health found that low blood serum levels are linked to higher mortality rates. Those with vitamin D concentrations in the lowest quartile (less than 9 mg/mL) had twice the death rate as those in the highest quartile (greater than 35 ng/mL) after adjusting for age. The authors determined that serum 25 (OH)D concentrations of less than 30 ng/mL may be too low for safety.

However, until research prompts enough of a consensus to establish national absolute values for adequate and inadequate blood vitamin D levels, a dose of common sense and advice from your medical doctor are your best bets.

“Most Americans have insufficient levels of vitamin D, which has been linked to a number of health problems,” says Samuel S. Badalian, M.D., Ph.D., D.Med.Sc., director of the Gynecology-Urogynecology Center in Syracuse, N.Y. “However, it’s important to realize that upping your vitamin D won’t fix existing problems and it can’t completely prevent a problem. Adequate vitamin D is needed for prevention, which means to help lower your risk of developing the disease.”

2. Do I Need a Vitamin D Blood Test?

If you’re suspicious that you have symptoms that could be related to low vitamin D levels, you may want to undergo a blood test. Serum blood levels of vitamin D are believed to be stable for weeks, serving as a good biomarker for vitamin D adequacy, which is why physicians often use a simple blood test.

The symptoms associated with low vitamin D are so general they can just as easily be associated with a number of other ailments. This can make it difficult for physicians to substantiate medical necessity for a vitamin D test. (Few insurances pay for “screening” vitamin D tests; see “The Power of Insurers” section below.)

So what are the symptoms of low vitamin D levels? They often include:
• Weight gain
• Low bone density
• Fatigue
• Muscular cramps and weakness
• Joint pain, especially in the back and knees
• Blood sugar issues
• Low calcium levels in the blood
• Irritability
• Depression

Insurance Issues
Many insurers limit coverage for vitamin D blood testing to individuals at a high risk for vitamin D deficiency. Among those are people with:
• Bariatric surgery
• Crohn’s disease
• Chronic kidney disease
• Cystic fibrosis
• Dark skin, such as African Americans and Hispanics
• Granuloma-forming disorders
• High risk medications, such as anti-seizure medications, glucocorticoids, AIDS medications, antifungals, cholestyramine
• Inflammatory bowel disease
• Liver failure
• Obesity
• Osteoporosis

When a laboratory tests blood for vitamin D, it measures the amount of 25-Hydroxyvitamin D (25OHD) circulating in our blood. Many experts say that, for an accurate reading, you shouldn’t eat four or more hours prior to your appointment. The cost of the test is generally between $30 and $80. Coverage varies among insurers, so you need to check with them directly.

The laboratory will give your physician parameters for what their testing indicates is a low, normal, or high level. Note that different labs will have slightly different parameters, based on the individuality of their own tests.

Vitamin D Screening Tests
When multiple studies about the benefits of vitamin D started to appear in the late 1990s, a large number of doctors began regular screening tests. A screening test means there’s no known medical reason for doing the test. It’s basically to check—because of the seemingly wide-reaching health benefits of vitamin D—that a patient’s levels are acceptable. (Along the same lines, a screening mammogram is done to ensure that an otherwise healthy woman doesn’t have breast cancer.

Since a vitamin D blood test is costly, insurance companies began carrying an increased burden. Medicare, too, began feeling the hit.

“Blood tests for vitamin D levels—not advised unless a problem like bone loss is suspected—are soaring,” U.S. News & World Report noted on Nov. 16, 2016. “Under Medicare, there was an 83-fold increase from 2000 to 2010, to 8.7 million tests last year [2015], at $40 apiece. It’s Medicare’s fifth most common test, just after cholesterol levels and ahead of blood sugar, urinary tract infections, and prostate cancer screening.”

Enter the U.S. Preventative Services Task Force. This group of independent medical experts was formed in 1984 to improve healthcare by making evidence-based recommendations about preventive services like screening, counseling, and preventive medications. All 16 members are volunteers, and most are practicing physicians. When insurance companies write medical policies on the coverage of certain services, such as screening for vitamin D deficiency, they consult research studies, policies from the CMS (Centers for Medicare and Medicaid Services), and the U.S. Preventative Task Force.

In November 2014, the Task Force concluded that “the current evidence is insufficient to assess the balance of benefits and harms of screening for vitamin D deficiency in asymptomatic adults.” They stated that research did not support a clear definition of what defines vitamin D deficiency. As soon as this statement was released, insurance companies hastily rewrote medical policies to exclude vitamin D screening tests.

Most medical doctors agree, although they deal with patient demand for the testing. “If you don’t have a problem associated with low vitamin D, like osteoporosis,” says Dr. Samuel Badalian, “you probably do not need testing.”

3. Vitamin D Sources: Sunshine, Supplements, and Food

The reason vitamin D has been dubbed the “Sunshine Vitamin” is fairly obvious. The sun is your best, most natural form of supplementing vitamin D. When the sun’s UVB rays (ultraviolet B rays) hit our skin, cholesterol in your body converts to vitamin D.

Your body—arms, legs, face, trunk—needs direct exposure to the sunlight. You can absorb enough vitamin D during a period of 20 to 30 minutes in the midday sun, defined as between the hours of 10 a.m. and 3 p.m. The reason for that timeframe? The sun has to be at the proper angle in order for your body to absorb the rays and make vitamin D.

People who live in the northern latitudes (at 40° latitude and above) cannot absorb enough sunlight from October through May due to the angle of the sun. The Vitamin D Council advises that if your shadow is longer than you are tall, you’re not getting enough sun.

Another reason associated with a lack of sunshine is the skin cancer scare, which has caused people to go overboard with sunscreen and sun blocks. Sunscreen and clothing both stop your body from absorbing the sunshine necessary to make vitamin D.

While the threat of skin cancer from overexposure to the sun is serious, the limited amount of sun you need for your vitamin D levels is not likely to cause skin cancer. Those with dark complexions are also at risk of not absorbing enough sunlight for vitamin D.

The Vitamin D Council says you may be able to get vitamin D from an indoor tanning bed. Common sense, however, is important; it takes just a few minutes for you to absorb vitamin D via tanning bed rays. If possible, the Council advises, choose a low-pressure bed with a good amount of UVB light rather than high-intensity UVA light.

Do Vitamin D Supplements Help?
For those who cannot get enough sun exposure due to the limitations of climate, geographic location, or physical problems, a vitamin D supplement may help. A supplement is also the most consistent way to ensure adequate intake.

If your latest blood test indicated deficient or insufficient vitamin D levels, your physician will likely give you a prescription for a weekly dose of 50,000 IUs for a limited time period—eight to 12 weeks, for example. (It is not recommended that you try to duplicate this amount with over-the-counter supplements.)

You will then be advised about how much vitamin D you should take as a supplement to prevent another deficiency.

For those of us who simply want to ensure adequate vitamin D levels in our bodies, Dr. Holick believes vitamin D can be taken as:
• 3,000 IUs daily, or
• 21,00 IUs weekly, or
• 90,000 IUs monthly.

Some research indicates you must supplement between 3,000 IUs per day and 4,000 IUs per day to maintain blood levels around 50 ng/mL. That said, an acceptable approach for many people is 2,000 IUs per day, experts say, with a blood test two months later to see how you’re doing.

From there, you can adjust your dosage. Higher levels of vitamin D are often recommended for those with autoimmune disease, although you’ll want to consult your physician if you’re considering taking supplements at a rate of 5,000 IUs per day.

If you’re buying an over-the-counter supplement, experts recommend using vitamin D3. While all forms of vitamin D must be converted in the body to a more active form (calcitriol), research has shown that vitamin D3 is converted 500 percent faster than vitamin D2.

Vitamin D3 (cholecalciferol) is found in food and sun. A study from the Osteoporosis Research Center at Creighton University said that vitamin D3 is about 87 percent more potent in raising and maintaining vitamin D concentrations in the body than vitamin D2.

Vitamin D2 (ergocalciferol) is not naturally produced by your body; it’s a synthetic vitamin D, commonly found in plants. Researchers at the Appalachian State University’s Human Performance Lab found that vitamin D2 supplementation is associated with higher muscular damage.

In a double-blind study, researchers further found that taking vitamin D2 decreased levels of vitamin D3 in the body. Lead author David Nieman theorized that vitamin D2 causes something to occur at the muscle level that worsens damage following stressful exercise. As a result, he advised athletes in particular not to take vitamin D2.

Additional studies showing a weakness in vitamin D2 include:
• The American Journal of Clinical Nutrition found vitamin D2 does not help prevent fractures.
• Harvard Medical School found that multiple sclerosis symptoms—numbness, tingling, pain, vision disturbances, fatigue, dizziness—were worsened when the person was on vitamin D2 but improved with vitamin D3.
• A study published in the Journal of Clinical Endocrinology & Metabolism found that while vitamin D3 reduces death rates in adults, vitamin D2 does not.

Finally, when it comes to nutritional supplements, it’s important to note that the Food and Drug Administration (FDA) does not regulate them. The FDA watches the supplement industry to be certain no nutritional product claims that it can cure, mitigate, or prevent a disease. Products that make those types of claims must be approved by the FDA as drugs.

Multiple studies on over-the-counter bottles of supplements have shown that not all contain what the label claims. A study led by Erin S. LeBlanc M.D., MPH, found that slightly more than half of the vitamin D over-the-counter pills and a third of the vitamin D compounded pills met U.S. Pharmacopeial (USP) convention standards. While the researchers agreed that the lack of accuracy was not likely to cause harm, the supplementation was less accurate and therefore less likely to be effective.

The USP’s mission is to “improve global health through public standards and related programs that help ensure the quality, safety, and benefit of medicines and foods.” It is a non-profit scientific organization that “sets standards for the identity, strength, quality, and purity of medicines, food ingredients, and dietary supplements manufactured, distributed and consumed worldwide.”

A supplement bearing the USP seal has been verified to contain what the label indicates.

Food Sources of Vitamin D
Few foods contain natural vitamin D, but fish does. The exact amount can vary widely. Wild salmon tend to have the highest vitamin D content—as much as 1,500 IU per 3.5 oz serving. Farmed salmon has about 25 percent of that.

Farmed trout, blue fish, swordfish, and Mahi have about half. Cod, grey sole, haddock, and squid have less than 10 percent of that found in wild salmon.

Cooking can impact the amount of vitamin D found in foods. For instance, frying salmon can decrease its vitamin D content by 50 percent. Canning, freezing, and baking fish, however, does not make a lot of difference. Raw fish contains the highest level of vitamin D.

Fortified foods are generally a consistent source of vitamin D, with an average of 100 IUs per serving. Fortified foods include some breads, orange juices, cereals, yogurts, and cheeses.

Mushrooms form vitamin D when exposed to either natural sunlight or artificial UV light. Wild mushrooms, fresh or dried, are typically very high in vitamin D. Commercially produced mushrooms, grown in the dark, are not high in vitamin D unless they have been purposely exposed to light, so mushroom producers are trying to change that.

Natural vitamin D is in egg yolks, organ meats, and high-fat dairy. Most milk and dairy products are low in vitamin D unless fortified.

4. Vitamin D Research: What Studies Tell Us

In recent years, studies have linked vitamin D deficiency to a variety of disorders.

Cancer
A study of more than 17,000 cancer patients, published in the Journal of Clinical Endocrinology and Metabolism, found that a high vitamin D level when you’re diagnosed with cancer means you will more likely survive and stay cancer free.

Researchers looked at the results from 25 different studies involving 17,732 patients with cancer. They measured vitamin D levels at the time of the cancer diagnosis and tracked survival rates.

The study showed benefits from high vitamin D levels in surviving lung, stomach, prostate, colon/rectal, and breast cancer. They also saw benefits for lymphoma and leukemia. Overall, the study found that for every 4 mg/ml increase in vitamin D levels, cancer survival increased by 4 percent. The most impressive levels were:
• 45% more likely to survive colon/rectal cancer
• 37% more likely to survive breast cancer
• 52% more likely to survive lymphoma.

“Considering that vitamin D deficiency is widespread around the world, our suggestion is to ensure everyone has sufficient levels of this important nutrient—that is, circulating 25 (OH)D levels—greater than 30 ng/mL),” said lead author Hui Want, M.D. Ph.D, a professor at the Institute for Nutritional Sciences, Chinese Academy of Sciences.

Research at the Cancer Epidemiology Research Unit in Sydney, New South Wales, Australia, found that adequate levels of vitamin D are important for the integrity of your DNA, helping to protect it from oxidative damage.

Depression
Depression is linked to a deficiency of D3, the same form obtained through the sun. Sunlight is the best source of vitamin D3, the type that increases levels dopamine and serotonin, the feel-good chemicals in the brain.

A University of Bristol study published in the January 2012 Journal of Child Psychology and Psychiatry looked at vitamin D levels in children when they were 9 years old and found that those with higher levels of vitamin D were 10 percent less likely to show signs of depression when they were tested again at 13. (Note: Vitamin D supplements are not recommended for children without information from your pediatrician.)

In 2013, researchers from McMaster University in Ontario, Canada, determined that low vitamin D levels are associated with depression. The study was published in the British Journal of Psychiatry. After screening thousands of studies, the researchers found 16 with a total of 31,424 participants that met the study’s criteria for a meta-analysis. Their conclusion: That overall, people with depression had lower vitamin D levels than controls without depression. The lowest vitamin D levels had a significantly increased risk of becoming depressed.

After the McMaster study, researchers from the Amsterdam University Medical Center in the Netherlands published a study that found low vitamin D levels are associated with depression and linked it to depression severity. The study included 1,102 people with current depression. Of those, 33.6 percent had deficient or insufficient vitamin D, defined as a serum 25 (OH)D level less than 20 ng/ml. The more severe the symptoms of depression, the lower their vitamin D levels.

In addition, the Amsterdam research found that the lower the vitamin D levels, the more at risk the participant was of having a depressive disorder two years later. People with the lowest levels of vitamin D were 11 times more prone to be depressed than those with normal levels.

Fatigue
Researchers at Newcastle University in the United Kingdom compared muscle function and recovery in 12 patients with vitamin D deficiency and 15 controls with normal vitamin D levels using magnetic resonance spectroscopy (NRS). NRS shows in real time how mitochondria inside muscle cells function.

Mitochondria manufacture ATP, the body’s main energy currency. ATP, or adenosine triphosphate, is an energy storage molecule. Suboptimal mitochondria function has been implicated in several fatigue-related disorders, as has low vitamin D. Researchers wanted to see how vitamin D treatment affected muscle energy metabolism.

Mitochondrial function in the vitamin D-deficient patients’ muscles improved after vitamin D supplementation. The improvement in the mitochondria’s ability to generate energy correlated with the improvements in vitamin D levels. All patients reported an improvement in fatigue after vitamin D therapy.

A study by the Endocrinology Department at St. George Hospital in Australia explored the effects of different doses of vitamin D on a test subject’s strength and muscle function. Researchers randomly assigned 30 vitamin D deficient patients either 2,000 or 5,000 IU of vitamin D per day for three months. At the end of the study, only five subjects (45 percent) in the 2,000 IU group—compared to 14 (93 percent) in the 5,000 IU group achieved a final concentration of at least 30 ng/mL. Muscle strength improved in both groups. Researchers concluded 5,000 IU daily is more effective than 2,000 IU for vitamin deficiency.

Your muscle will function better and procure more energy with vitamin D supplements because it helps improve the mitochondria’s ability to generate ATP. You may also see improvements in your mood, brain function, and other physical symptoms.

Female Pelvic Floor Disorders
A 2010 study by Samuel S Badalian M.D., Ph.D., director of the Gynecology-Urogynecology Center in Syracuse, N.Y., and Paula Rosenbaum, Ph.D., found that higher vitamin D levels were linked to a lower risk for such female pelvic floor disorders as uterine prolapse and urinary incontinence.

The study data included 1,881 non-pregnant women over 20 years old in whom pelvic floor disorders and vitamin D measurements were available. Data were analyzed regarding demographics, pelvic floor disorders, and vitamin D levels. After controlling for known risk factors, the researchers calculated odds ratios to determine associations between vitamin D levels and pelvic floor disorders.

Findings showed one or more pelvic floor disorders in 23 percent of the participants. Women reporting at least one pelvic floor disorder and those with urinary incontinence had significantly lower mean vitamin D levels.

With increasing vitamin D levels, risks for pelvic floor disorders were significantly decreased. In women at least 50 years old with vitamin D levels at or less than 30 ng/mL (i.e., not insufficient), the risk of urinary incontinence was significantly reduced.

The researchers concluded that further evaluation of the role of vitamin D is needed, but their findings suggest that vitamin D insufficiency and deficiency in women could improve pelvic muscle strength and possible reduce the prevalence of pelvic floor disorders, including urinary incontinence.

Graves’ Disease/Hyperthyroidism
Graves’ disease is an autoimmune condition that leads to an overproduction of thyroid hormones. It is the most common autoimmune disorder in the United States. Symptoms include rapid heartbeat, sweating, muscle weakness, tremor, and anxiety.

People with Graves’ disease are more likely to be deficient in vitamin D, and low vitamin D levels increase the risk of Graves’ disease.

Certain mutations in the vitamin D receptor gene are linked to a higher incidence of autoimmune thyroid diseases, including Graves’ disease. Vitamin D exerts hormone-like actions on the cells of the immune system, generating anti-inflammatory effects, and helping to regulate the immune system.

High Blood Pressure
A study presented at the European Human Genetics Conference in 2013 made a discovery showing that vitamin D deficiency can cause high blood pressure.

Although other studies had shown a link, this large-scale study showed cause and effect, which is a significant finding. Data was used from 35 studies that included 155,000 participants.

The study found that for every 10 percent increase in vitamin D levels, there was an 8 percent decrease in the risk of developing hypertension. This study data suggests that some types of cardiovascular disease could be prevented through vitamin D supplements or increased vitamin D consumption through food.

A study by a team of doctors from Brigham and Women’s Hospital in Boston showed that taking vitamin D3 supplements for three months significantly lowers blood pressure readings.

The participants received either a placebo, 1,000, 2,000, or 4,000 IUs of vitamin D daily for three months. The results, which were published in the medical publication Hypertension, showed that as vitamin D supplement levels went up, systolic blood pressure went down.

In fact, the higher the dose, the more blood pressure was reduced:

• those taking 1,000 IUs decreased by 0.7 mmHg
• those taking 2,000 IU decreased by 3.4 mmHg
• those taking 4,000 IU decreased by 4.0mmHg

Overall, researchers found that systolic (top reading) blood pressure decreased by an average of -1.4 mmHg for each additional 1,000 IU per day of vitamin D3 taken.

Muscle Strength
A 2015 study showed that postmenopausal women with type 2 diabetes who had vitamin D levels below 30 ng/mL were given 6,600 IU of vitamin D per week or a placebo for three months. At the end of the study, those women who were given vitamin D showed significant improvements in grip strength over the control group.

In another study, women taking 1,000 IUD vitamin D daily had a 25.3percent increase in muscular strength, while women receiving placebo had a 6.8 percent loss in lean muscle mass. Women who received no vitamin D were twice as likely to fall.

Osteoporosis
The annual incidence of fractures due to osteoporosis in women over 50 is greater than the combined chances of heart attack, stroke, and breast cancer—and vitamin D deficiency may be a factor.

In patients with osteoporosis, wrist fractures tend to occur 15 years earlier than hip fractures. A study presented at the American Academy of Orthopaedic Surgeons’ 2012 annual meeting reported that low levels of vitamin D were found in 44 percent of postmenopausal women with wrist fracture.

Vertigo
A 2013 study published in The Journal of Neurology found vitamin D levels in people with benign paroxysmal positional vertigo (BPPV) to be 4.5 ng/mL lower than healthy controls. BPPV is a state of dizziness and spinning that can be debilitating, has been associated with osteoporosis and poor bone health. Very low levels have also been associated with the recurrence of BPPV. Given that problems with calcium metabolism is what causes our bones to lose density, it makes sense when you realize that BPPV is caused by degradation of calcium deposits in the ear.

Weight Gain
A 2012 study by Dr. Erin LeBlanc, an endocrinologist and researcher at the Kaiser Permanente Center for Health Research in Portland, Ore., showed that women with low levels of vitamin D may be more susceptible to weight gain. The study was reported in the Women’s Journal of Health.

Weight Loss
A study published in the Journal of the American Geriatrics Society, selected 218 women, ages 50 to 75, all overweight or obese and with insufficient vitamin D levels. The participants underwent a weight-loss program that combined calorie reduction of 500 to 1,000 fewer calories per day and 225 minutes a week of moderate to fibrous aerobic exercise. Participants were also assigned either a placebo or 2,00 IU of vitamin D daily.

Both groups lost a little over 8 percent of body weight. The extra vitamin D did boost blood levels of vitamin D in the supplement group, but little difference was found for muscles and bones. A small subgroup with sarcopenia (frailty associated with loss of lean muscle mass) did seem modestly more favorable changes.

Obese individuals are more likely to have low levels of vitamin D, which is known to benefit muscles and bones, so some people take supplemental vitamin D during weight loss. Turns it out that doesn’t necessarily make sense.

Obese women who lose weight also lose lean muscle mass and bone mineral density, particularly if they are inactive, putting them at greater risk of frailty and falls.