Vitamin d3 recommended daily allowance

How much vitamin D do I need?

In November 2010, the Institute of Medicine’s expert committee set a new “dietary reference intake” for vitamin D.

Assuming that a person gets virtually no vitamin D from sunshine — and that this person gets adequate amounts of calcium — the IOM committee recommends getting the following amounts of vitamin D from diet or supplements (Note that the IOM’s upper limit is not a recommended intake, but what the IOM considers the highest safe level):

That’s not enough, says Boston University vitamin D expert Michael Holick, MD, PhD, professor of medicine, physiology, and biophysics, Boston University Medical Center. Holick recommends a dose of 1,000 IU a day of vitamin D for both infants and adults — unless they’re getting plenty of safe sun exposure.

In 2008, the American Academy of Pediatrics recommended that breastfed infants receive 400 IU of vitamin D every day until they are weaned. This doubled the AAP’s previous recommendation.

The AAP also recommends 400 IU/day of vitamin D for children and teens who drink less than a quart of vitamin D-fortified milk per day.

The Vitamin D Council recommends that healthy adults take 2,000 IU of vitamin D daily — more if they get little or no sun exposure.

There’s evidence that people with a lot of body fat need more vitamin D than lean people.

But it’s clear that the IOM’s conservative recommendations will stir debate in the scientific and medical communities. Here’s a rule of thumb: If you’re considering taking more vitamin D than the IOM committee recommends, first check with your doctor or pediatrician.

Next: Can I get too much vitamin D?

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Recent media reports and studies have left many confused about calcium supplements and their effect on the heart. While some studies have suggested a possible link between calcium supplements and heart-related problems, substantial evidence supports that taking the recommended amount of calcium supplements poses no risk to the heart.

What we know is that experts agree getting enough calcium is critical for bone health and overall health. And we also know that osteoporosis medications don’t work without calcium and vitamin D.

NOF recommends the following three steps for bone health:

  1. Aim to get the recommended daily amount of calcium you need from food first and supplement only as needed to make up for any shortfall. Use our calcium calculation tool to estimate your daily calcium intake from food and review our list of calcium-rich foods for new ideas to help you incorporate calcium in your diet.
  2. Maintain an overall healthy lifestyle by eating plenty of fruits and vegetables, exercising and not smoking or drinking too much alcohol.
  3. If you are diagnosed with osteoporosis, work with your healthcare provider to determine an appropriate treatment plan that includes calcium, vitamin D, safe exercise and medication. Follow your plan and consult with your healthcare provider before deciding to stop taking your supplements or medication.

How much calcium and vitamin D do you need?

NOF recommends that women age 50 and younger get 1,000 mg of calcium from all sources daily and that women age 51 and older get 1,200 mg. For men, NOF recommends 1,000 mg of calcium daily for those age 70 and younger and 1,200 mg for men age 71 and older.

And don’t forget about vitamin D, which enables your body to absorb calcium. Most adults under age 50 need 400-800 international units (IU) daily and most adults age 50 and older need 800-1,000 IU daily. Some people need more vitamin D to maintain healthy blood levels of the vitamin, so be sure to talk with your healthcare provider to determine the amount that’s right for you. Visit Calcium and Vitamin D: What You Need to Know for our complete recommendations on calcium and vitamin D.

Remember, regardless of what you hear or read, always talk to your healthcare provider about your individual needs for calcium and vitamin D and never stop taking your supplements without talking to your healthcare provider first.

Vitamin D supplementation recommended in all children, teens

SAN FRANCISCO – Vitamin D deficiency is common among children and adolescents, particularly those with chronic disease, Catherine Gordon, MD, said at the annual meeting of the American Academy of Pediatrics.

Yet the precise definition of vitamin D deficiency and the healthy threshold for vitamin D levels lack universally agreed-upon standards. Generally speaking, levels of at least 30 ng/mL (75 nmol/L) appear safe and reasonable for children with chronic disease, and additional research is confirming whether this range is appropriate for other pediatric groups as well. Although too much vitamin D can lead to hypercalcemia, vitamin D intoxication is very rare, said Dr. Gordon, director of the division of adolescents and transition medicine at the University of Cincinnati.

©Kaspri/Fotolia.com Those at the highest risk for vitamin D deficiency include people who eat an inadequate diet and/or get inadequate exposure to sunlight, including those who live in high latitudes or use sunscreen frequently. Obesity, malabsorption issues, taking anticonvulsants, and having a dark skin pigmentation are additional risk factors. Malabsorption can result from conditions such as celiac disease, cystic fibrosis, inflammatory bowel disease, or kidney problems.

Severe vitamin D deficiency can lead to rickets, when bones have insufficient calcium and phosphorus levels, resulting in bone softening and weakening before growth plates close. If not treated with vitamin D and calcium supplementation, rickets becomes osteomalacia after the growth plates close.

Vitamin D deficiency rates vary by population

It’s difficult to pin down rates of vitamin D deficiency. One 2004 study of just over 300 children found nearly a quarter of them (24%) were deficient based on a threshold of levels below 15 ng/mL, and another 42% had insufficient levels, defined as 20 ng/mL or lower, but all were asymptomatic. Another 2008 study using different cut-offs found that 12% of healthy 8- to 24-month-olds were deficient, defined as levels below 20 ng/mL. Forty percent of the children had suboptimal levels below 30 ng/mL. Overall, a third of the children showed demineralization on their x-rays. While the season of the year and race/ethnicity did not emerge as predictors of vitamin D insufficiency, breastfeeding without supplementation and lack of milk consumption did.

Because the vitamin D content in human breast milk is low, breastfed infants typically develop low vitamin D levels unless they receive supplementation or plenty of exposure to sunlight. A maternal dose of 6,400 IU of vitamin D is needed for breastfed infants to reach normal vitamin D levels, Dr. Gordon said. Babies born to mothers with vitamin D deficiency have the highest risk of becoming deficient themselves, although formula-fed babies usually receive plenty through the vitamin D fortification in infant formula.

Among adolescents, obesity remains a common risk factor, and those with obesity require higher doses to correct deficiency or insufficiency. A study in the Journal of Pediatrics this year found that adult-sized teens need at least 5,000 IU of vitamin D3 a day for 8 weeks to correct deficiency. Similarly, a small 2012 study of 61 children and adolescents with inflammatory bowel disease found that supplementation of 2,000 IU of vitamin D3 daily or 50,000 IU of D2 weekly, for 6 weeks, more effectively corrected vitamin D deficiency than 2,000 IU daily of vitamin D2 without any changes to parathyroid hormone suppression.

How much to supplement

Much debate and uncertainty surround how much (if at all) healthy infants, children, and adolescents should be supplemented with vitamin D. The American Academy of Pediatrics recommends daily supplementation of 400 IU of vitamin D from birth through adolescence for all children and teens, although that’s far below the safe upper limit of vitamin D intake, Dr. Gordon said.

The health and sciences division (formerly the Institute of Medicine) of the National Academies of Sciences, Engineering, and Medicine, by contrast, recommends a daily intake of 400 IU of vitamin D for the first year of life and then 600 IU for age 1 through old age. The safe upper limits set by the health and sciences division include 1,000 IU for infants up to 6 months old, 1,500 IU for infants aged 6 months to 1 year, 2,500 IU for toddlers up to 3 years, 3,000 IU for children aged 4-8 years, and 4,000 IU for those 9 years and older.

Yet the Endocrine Society recommends a greater amount of supplementation for children at risk for vitamin D deficiency or low bone density mass: from 400 to 1,000 IU for children 1 year and younger, and 600-1,000 IU for all older children, adolescents, and adults. The Endocrine Society also cites a higher safe upper limit of 2,000 IU for infants up to 12 months and 4,000 IU for those aged 1 year and up.

Part of the discordance in these recommendations lies in what populations they are aimed at, Dr. Gordon explained. While the health and sciences division recommendations were written for healthy children and adolescents, the Endocrine Society is specifically addressing those in risk groups, such as transplant recipients, those with chronic conditions that can cause malabsorption, and those taking anticonvulsants or receiving other treatments that can threaten bone health. Among older children and adolescents, anorexia nervosa is also a risk factor for inadequate vitamin D levels.

Dr. Gordon recommended 600 IU of vitamin D daily for all healthy children and teens while noting that those in risk groups may require 1,000-2,000 IU to prevent vitamin D deficiency.

Additional concerns with inadequate vitamin D

Aside from bone mineral density and levels of 25(OH)D (25-hydroxy vitamin D) and parathyroid hormone, vitamin D insufficiency may be suspected based on several other biomarkers, including fractures or falls, intestinal calcium absorption, dental health, insulin sensitivity, beta-cell or immune functioning, respiratory disease such as wheezing or tuberculosis, and possibly hypertension.

Researchers have developed new interest in exploring whether factors during childhood and adolescence – critical years for bone acquisition – such as vitamin D levels might influence the risk for osteoporosis later in life, Dr. Gordon said.

Both males and females reach their peak bone mass and skeletal strength in their early to mid-20s and maintain these through about their mid-40s. While individuals have no control over intrinsic factors that help determine their bone mass, such as sex, family history, and ethnicity, other extrinsic factors are also bone mass determinants, including diet, body mass, a particular individual’s hormonal mix, illnesses and their treatments, physical activity level, and lifestyle choices.

Therefore, health providers should encourage patients to regularly exercise, maintain a healthy weight, eat healthfully, and take daily supplements, Dr. Gordon said. She only recommended testing 25(OH)D levels in those at risk for deficiency and/or low bone mass.

Dr. Gordon reported no relevant financial disclosures.

How much vitamin D do you need?

Despite widespread assertions in the popular and scientific press that many Americans have a vitamin D deficiency, the term “deficiency” isn’t strictly accurate. The official definition of a vitamin deficiency means that specific health problems stem solely from the lack of (or inability to use) a specific nutrient. An actual vitamin D deficiency results in bone disease, such as rickets, which is rare in the United States.

On the other hand, lower-than-optimal levels of specific vitamins, including vitamin D, may increase your risk of numerous health problems, even though they are not solely responsible for these problems. “Insufficiency” may be a better term for these lower levels than “vitamin D deficiency”.

So far, the most clearly established benefit of vitamin D is that it helps the body absorb calcium and therefore promotes healthy bones. However, a steady drumbeat of studies beginning in the 1980s started to build a case that low blood levels of D were connected with a variety of chronic health problems, leading to claims by a number of researchers that the RDA for D was way too low. The confusion and controversy surrounding optimal vitamin D intake and blood values prompted the U.S. and Canadian governments to request that the Institute of Medicine (IOM, now called the Health and Medicine Division) review the evidence on vitamin D and calcium and update the DRIs.

The long-awaited report, Dietary Reference Intakes for Calcium and Vitamin D, was published in 2011. The IOM concluded that evidence for benefits other than improved bone health came from studies that could not be considered reliable and provided often-conflicting results.

Based on the evidence for bone benefits, however, the IOM panel increased the RDA for vitamin D to 600 IU for people up to age 70 and to 800 IU for those over 70. That’s a fairly sizable boost over the previous recommendations of 200 IU per day through age 50, 400 IU for ages 51 to 70, and 600 IU for ages over 70. The IOM also raised the safe upper limit of daily intake for most age groups from 2,000 to 4,000 IU.

But ultimately, the amount of vitamin D that makes it into your bloodstream is more important than how much you’re consuming. There again controversy reigns. While some people argue for much higher levels, the IOM report concluded that vitamin D blood levels above 20 ng/ml are adequate for maintaining healthy bones, and that most people in the United States have values in that range. Other organizations, including the American Association of Clinical Endocrinologists, assert that values between 30 and 50 ng/ ml have potential health benefits beyond bone health, so the issue is still not resolved. However, the IOM report cautioned that exceptionally high levels of vitamin D have not been proven to confer additional benefits and have been linked to health problems, challenging the notion that “more is better.”

Most healthy adults without symptoms related to vitamin D deficiency do not need to have their blood levels measured. People who should consider vitamin D testing are those with medical conditions that affect fat absorption (including weight-loss surgery) or people who routinely take anticonvulsant medications, glucocorticoids, or other drugs that interfere with vitamin D activity.

To learn more about the vitamins and minerals you need to stay healthy, read Making Sense of Vitamins and Minerals, a Special Health Report from Harvard Medical School.

Disclaimer:
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

Taking too much vitamin D can cloud its benefits and create health risks

Some people are overdoing it in search of better health.

Updated: December 15, 2019Published: November, 2017

Vitamin D is having its day in the sun. In recent years, research has associated low blood levels of the vitamin with higher risks of everything from heart disease, diabetes, and cancer to mood disorders and dementia. The findings have not gone unnoticed. Vitamin D supplements and screening tests have surged in popularity.

“Vitamin D testing is one of the top Medicare lab tests performed in the United States in recent years,” says Dr. JoAnn E. Manson, the Michael and Lee Bell Professor of Women’s Health at Harvard Medical School. “This is really surprising for a test that is recommended for only a small subset of the population.”

Unfortunately, this vitamin D trend isn’t all blue skies. Some people are overdoing it with supplements. Researchers looking at national survey data gathered between 1999 and 2014 found a 2.8% uptick in the number of people taking potentially unsafe amounts of vitamin D — that is, more than 4,000 international units (IU) per day, according to a research letter published in the June 20 issue of The Journal of the American Medical Association (JAMA). And during the same time period there was nearly an 18% increase in the number of people taking 1,000 IU or more of vitamin D daily, which is also beyond the dose of 600 to 800 IU recommended for most people.

Vitamin D and your health

Vitamin D, nicknamed the sunshine vitamin because your body produces it after sun exposure, has long been known to help build strong bones by increasing the body’s absorption of calcium and phosphorous. But beginning in 2000, research into vitamin D’s role in other health conditions began to expand rapidly.

While there is strong support for vitamin D’s role in bone health, the evidence that it prevents other health conditions is not yet conclusive, says Dr. Manson. “Research on vitamin D and calcium supplementation has been mixed and, especially when it comes to randomized clinical trials, has been generally disappointing to date,” she says.

Dr. Manson was a principal investigator of the recently published Vitamin D and Omega-3 Trial (VITAL), a large study (more than 25,000 participants nationwide). The study found that those taking a vitamin D supplement did not lower rates of heart attack, stroke, or cancer. However, among people who later developed cancer, those who took vitamin D supplements for at least two years had a 25% lower chance of dying from their cancer compared with those who received a placebo.

Factors that might affect your vitamin D levels

Your vitamin D levels reflect many factors. For example:

Where you live. If you live in the northern states (latitudes north of 37°), you are at higher risk for a vitamin D deficiency because your skin may not be able to produce any vitamin D from sun exposure during the winter months.

Your age. Your skin’s ability to produce vitamin D drops with age. If you’re over age 65, you generate only one-fourth as much vitamin D as you did in your 20s.

Your skin color. People with darker skin typically have lower levels of vitamin D than lighter-skinned individuals. African Americans have, on average, about half as much vitamin D in their blood compared with white Americans.

Your weight. If you have a body mass index above 30, you may have low blood levels of vitamin D. Vitamin D is stored in fat, so in people with obesity, less of the vitamin circulates in the blood, where it’s available for use by the body.

The foods you eat. Very few foods naturally contain vitamin D. The U.S. government started a vitamin D milk fortification program in the 1930s to combat rickets, a bone-weakening disease caused by vitamin D deficiency, which was a major public health problem at the time. Breakfast cereals and some types of orange juice may also be fortified, but this varies by brand. So, the amount of vitamin D you get from food depends on the food you eat and how much milk you drink.

Certain health conditions. People with conditions such as inflammatory bowel disease, liver disease, or cystic fibrosis, among others, may have trouble absorbing vitamin D, which can lead to deficiencies.

Looking for the link

Despite the fact that some studies have found an association between low blood levels of vitamin D and various diseases, it hasn’t been proven conclusively that a vitamin D deficiency actually causes disease, says Dr. Manson.

For example, a person with a serious illness may have a vitamin D deficiency. But that may have developed because she or he spends little time outdoors being physically active or because the person has a poor diet, both of which are risk factors for many diseases, as well as for deficiency, says Dr. Manson. Another issue is that diseases can cause inflammation, which can reduce vitamin D levels in the blood. Obesity, which has its own links to many conditions, can also reduce the amount of vitamin D in the blood because your body stores the vitamin in fat tissue, removing it from the bloodstream, where it would show up on tests. “Thus, a low vitamin D level may be a marker for other conditions, but not necessarily a direct cause of disease,” says Dr. Manson.

In addition to figuring out whether a lack of vitamin D causes disease, more studies are needed to determine if taking a supplement can reduce these risks, says Dr. Manson.

Vitamin D benefits and warnings

Although the research is still hazy, some people will benefit from taking vitamin D supplements, along with sufficient calcium intake, to promote their bone health. But they don’t require large amounts of vitamin D to get the benefit. “More is not necessarily better. In fact, more can be worse,” says Dr. Manson. For example, a 2010 study published in JAMA showed that intake of very high doses of vitamin D in older women was associated with more falls and fractures.

In addition, taking a supplement that contains too much vitamin D can be toxic in rare cases. It can lead to hypercalcemia, a condition in which too much calcium builds up in the blood, potentially forming deposits in the arteries or soft tissues. It may also predispose women to painful kidney stones.

If you’re taking vitamin D supplements, the take-home message is moderation. Taking too much can limit the benefits of the sunshine vitamin.

Selected food sources of vitamin D

Food

International units

Salmon, pink, cooked, 3 ounces

Tuna fish, canned in oil, drained, 3 ounces

Sardines, canned in oil, drained, 3 ounces

Milk, nonfat, fortified, 8 ounces

Orange juice, fortified, 8 ounces

Egg, whole, cooked, scrambled, 1 large

Cheddar cheese, 1 ounce

Frozen yogurt, flavor other than chocolate, 8 ounces

Source: USDA National Nutrient Database for Standard Reference.

Be smart about D

To safely take vitamin D supplements, it’s best to stick to some simple guidelines:

Watch your numbers. If you’re taking a vitamin D supplement, you probably don’t need more than 600 to 800 IU per day, which is adequate for most people. Some people may need a higher dose, however, including those with a bone health disorder and those with a condition that interferes with the absorption of vitamin D or calcium, says Dr. Manson. Unless your doctor recommends it, avoid taking more than 4,000 IU per day, which is considered the safe upper limit.

Choose food over pills. If possible, it’s better to get your vitamin D from food sources rather than supplements (see “Selected food sources of vitamin D.”) Choose fortified dairy products (which have the nutrient added to the food), fatty fish, and sun-dried mushrooms, which are all high in vitamin D. The FDA has made it easier for you to see how much you’re getting, thanks to new nutrition labels that list the vitamin D content of foods.

Let your doctor know. “Many people are taking high-dose supplements on their own and their doctors may not even be aware of it,” says Dr. Manson. Discuss supplement use with your doctor to ensure that the amount you’re taking is appropriate for your needs. If you have a well-balanced diet, which regularly includes good sources of vitamin D, you may not need a supplement at all.

Image: © Hunterann/Getty Images

Disclaimer:
As a service to our readers, Harvard Health Publishing provides access to our library of archived content. Please note the date of last review on all articles. No content on this site, regardless of date, should ever be used as a substitute for direct medical advice from your doctor or other qualified clinician.

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