What Is In Vitamin D

What Happens If I Take Too Much Vitamin D

Taking too many vitamin D supplements over a long period of time can cause too much calcium to build up in the body . This can weaken the bones and damage the kidneys and the heart.

If you choose to take vitamin D supplements, 10 micrograms a day will be enough for most people.

Do not take more than 100 micrograms of vitamin D a day as it could be harmful. This applies to adults, including pregnant and breastfeeding women and the elderly, and children aged 11 to 17 years.

Children aged 1 to 10 years should not have more than 50 micrograms a day. Infants under 12 months should not have more than 25 micrograms a day.

Some people have medical conditions that mean they may not be able to safely take as much. If in doubt, you should consult your doctor.

If your doctor has recommended you take a different amount of vitamin D, you should follow their advice.

You cannot overdose on vitamin D through exposure to sunlight. But always remember to cover up or protect your skin if you’re out in the sun for long periods to reduce the risk of skin damage and skin cancer.

Page last reviewed: 03 August 2020 Next review due: 03 August 2023

Vitamin D Toxicity And Side Effects

Vitamin D toxicity is rare but can lead to a host of symptoms and complications.

How much is too much? The amount of vitamin D you need is dependent on the factors described previously. For adults, the maximum amount of vitamin D you should take according to the National Institutes of Health is 4,000 IU. For children, the amount is less, depending on their age.

Signs of vitamin D toxicity are:

Nutritional Research To Address And Understand Vitamin D Insufficiency

Table 2. List of ongoing large nutritional vitamin D3 supplementation trials using nutrition-related daily vitamin D3 doses .

Vitamin D3 once in the blood immediately binds to the vitamin D-binding protein and gets transported into the liver . The first hydroxylation at position 25 generates the major circulating metabolites 25-hydroxyvitamin D3. This metabolite circulates throughout all organs and undergoes hydroxylation at position 1, which occurs mainly in the kidney, but also in other organs, to form 1,25-dihydroxyvitamin D3, the active hormone. Besides the major circulating metabolite 25-hydroxyvitamin D3 and the hormonally active metabolite 1,25-dihydroxyvitamin D3, more than 35 additional vitamin D3 metabolites are formed by the body . It is speculated that they might be intermediates in the catabolism of 1,25-dihydroxyvitamin D3. The human body has evolved many CYP enzymes and invests energy to form these additional 35 vitamin D3 metabolites, whether this is for the purpose to catabolize 1,25-dihydroxyvitamin D3, remains still to be answered. More appealing is the theory that these metabolites are formed to fulfill yet unknown functions of vitamin D3. This perspective could potentially also account to the pleiotropic non-skeletal health benefits reported by the many vitamin D intake studies. For some of the vitamin D3 metabolites like the 24R,25-dihydroxyvitamin D3 potential function was explored in vitro .

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What Happens If I Overdose

Seek emergency medical attention or call the Poison Help line at 1-800-222-1222. An overdose of vitamin D can cause serious or life-threatening side effects.

Overdose symptoms may include nausea, loss of appetite, thirst, urinating more or less than usual, body aches, stiffness, confusion, or irregular heartbeats.

What Causes Low Vitamin D

Anything that interferes with the bodys ability to make vitamin D through the skin, including liver or kidney disease, can cause deficiency. Malabsorption syndromes or a diet low in foods containing vitamin D can also lower vitamin D levels.

The following factors may interfere with our body’s ability to make vitamin D:

• Chronic illness or disability that prevents regular sun exposure
• Living at latitudes above 37 degrees north or below 37 degrees south of the equator over winter, although this is controversial, and studies have shown only Caucasians show a correlation with low vitamin D levels and latitude.
• Skin color: Individuals with a darker skin produce less vitamin D with the same amount of sunlight exposure than individuals with lighter skin color.
• Age: Older people are less efficient at making D3 and less likely to go outside in the sun.
• Religion or culture: People whose beliefs require them to cover most of their skin and/or face usually do not receive adequate sunlight for their skin to make vitamin d.
• Avoidance of the sun and use of sunscreen: Fears of skin cancer and skin aging mean people spend less time in the sun than in the past, although only 10 minutes of direct summer sun is necessary to make an adequate daily dose of vitamin D.

In addition, a poor intake of vitamin D through the diet may also contribute however, studies have shown less than 10% of the vitamin D in our body is obtained through diet, so it is not considered a major contributing factor.

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How Can I Make Sure My Child Is Getting Enough Vitamin D

Your childs age matters when it comes to cows milk. For children older than 12 months, plain whole cows milk is a great source of vitamin D.

Most cows milk sold in stores is fortified with vitamin D. For babies younger than 12 months, cows milk is not recommended because it may put your baby at risk for intestinal bleeding. It also has too many proteins and minerals for your babys kidneys to handle easily and does not have the right amount of nutrients your baby needs.

For babies who are fed onlybreast milk or who receive both breast milk and infant formula:

• Breast milk usually does not provide all the vitamin D a baby needs, so breastfed babies will need a supplement of 400 IU of vitamin D per day beginning shortly after birth.

For babies who are receiving onlyinfant formula:

• Vitamin D supplementation is not needed.
• Infant formulas are fortified with vitamin D.

What Is Vitamin D

Vitamin D has to be one of sciences most misunderstood vitamins.

For a start, it is not actually a vitamin, but a prohormone, which means that it is converted into a hormone by our body. It is also not just one substance, but five different substances, of which two have been identified as being the most important to humans. These are:

In addition, research has discovered that vitamin D is not only vital for calcium absorption and bone growth and remodeling, but several other important processes as well, such as modulating cell growth and immune system function.

Vitamin D acts on our bones, intestines, kidneys and parathyroid glands to keep calcium in balance throughout our body. Vitamin D receptors are also located within our cardiovascular system, lungs, pancreas, skeletal muscle, skin, and reproductive organs. In summary, vitamin D is a prohormone that is essential for good health.

Only 10% of the vitamin D our body needs is obtained from food. The rest is made by our bodies when our skin is exposed to sunlight.

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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 with chronic kidney or liver disease.
• People with hyperparathyroidism
• People with sarcoidosis, tuberculosis, histoplasmosis, or other granulomatous disease
• People with some lymphomas, a type of cancer.
• People who take medicines that affect vitamin D metabolism, such as cholestyramine , 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.

Why Certain People May Need A Vitamin D Supplement

Why are some groups at greater risk of low vitamin D levels? In most cases, it can be traced back to their diet or lifestyle. Take vegans, for instance. Many have low vitamin D levels because they avoid foods that are rich in vitamin D including meat, fish, egg yolks, and dairy products that have been fortified with the vitamin. One study published in February 2016 in PLoS One found vitamin D serum concentration was 34 percent lower among study participants who followed a vegan diet compared with those who ate meat and dairy.

But there are ways to get added Vitamin D into your diet as a vegan. For instance, plant milk beverages, such those made from soy, oats, and almond, are often fortified with vitamin D to the level found in fortified cows milk , according to the National Institutes of Health. Check the nutrition facts label for the actual amount.

People with obesity also may need a supplement. Research has suggested the possible reasons for deficiency include a lower dietary intake of vitamin D among obese men compared with nonobese men and women, the possibility that obese people expose less skin to the sun , and a decrease in the absorption rate of vitamin D among people whove had bariatric or gastric bypass procedures. Indeed, one study suggested recommendations for vitamin D targets should be based on body weight rather than simply suggesting 600 IU for everyone across the board.

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How Much Vitamin D And Calcium Do You Need

The Endocrine Society and The Institute of Medicine have suggested recommended daily allowances for vitamin D and calcium, as well as maximum daily consumption amounts that you should not exceed for your safety:

The recommendations come with two precautions:

• Some people may need more than the RDA if they are:

• Taking anticonvulsant medications, glucocorticoids, antifungals such as ketoconazole or medications for AIDS

• Taking too much of either nutrient appears to be harmful, with:

• Kidney stones associated with too much calcium from supplements

• Very high levels of vitamin D potentially causing kidney and tissue damage

Is It Best To Get Your Vitamin D From The Sun Definitely Not

David J. Leffell, MD, Yale Medicine dermatologist and chief of Dermatologic Surgery

One of the biggest challenges weve faced in dermatology and in the world of skin cancer prevention has been a lot of misinformation about vitamin D metabolism.

There are claims that one needs to get a certain amount of sun exposure every day in order to produce enough vitamin D to be healthy. Its just not true. The majority of people can get their vitamin D from nutritional supplements and from vitamin D-fortified foods.

There are some people who have advocated for tanning to get vitamin D. But we know that UVB light causes skin cancer and that protecting yourself against it makes sense. As a doctor who treats patients who have melanomas, I want the general public to be advised that under no circumstances can use of a tanning bed or tanning in general be justified on the basis of vitamin D. Take a supplement instead.

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Roles Of Vitamin D In The Body

Vitamin D is a fat-soluble vitamin that is important for the bodys absorption of calcium and phosphorus, which are important for healthy teeth and bones. It also helps keep our bones and teeth healthy. There are two main sources of vitamin D: sun exposure and diet.

The important roles of vitamin D in body processes are:

• It regulate the immune system
• Supports muscle function
• Keeps our heart healthy

How Is Vitamin D Deficiency Treated

The goals of treatment and prevention for vitamin D deficiency are the same: to reach and then maintain an adequate vitamin D level in your body.

While you might consider eating more foods containing vitamin D and getting more sunlight, your healthcare provider will likely recommend taking vitamin D supplements.

Vitamin D comes in two forms: D2 and D3. D2 comes from plants. D3 comes from animals. You need a prescription to get D2. D3, however, is available over the counter. Your body more easily absorbs D3 than D2.

Work with your healthcare provider to find out if you need a vitamin supplement and how much to take, if needed.

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Daily Recommended Dose Of Vitamin D

The daily value for vitamin D is 800 IU . The vitamin D content is listed as a percentage of the DV on the nutrition facts label on food packages. This tells you what amount of your daily vitamin D requirement the food will provide .

Its best to get vitamin D from food or supplements.

Whether you need a vitamin D supplement in addition to food and sun exposure is a question to ask your doctor. They can also help you find out if you are deficient.

Here are 7 healthy foods that are high in vitamin D.

How Can I Prevent Vitamin D Deficiency

The best way to prevent vitamin D deficiency is to ensure youre getting enough vitamin D in your diet and/or through sun exposure. But be careful about being in the sun for too long without sunscreen. Excessive sun exposure puts you at an increased risk for skin cancer.

The amount of vitamin D you need each day depends on your age. The average daily recommended amounts are listed below in micrograms and International Units .

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

• Cows milk and soy, almond and oat milk.
• Breakfast cereals.
• Other dairy products, such as yogurt.

Vitamin D is in many multivitamins. There are also vitamin D supplements.

Talk to your healthcare provider if youre concerned about getting enough vitamin D.

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What Are The Possible Complications Of Vitamin D Deficiency

The most serious complications of vitamin D deficiency include:

• Low blood calcium levels .
• Low blood phosphate levels .

All of these conditions are treatable. While rickets is a treatable and often curable disease, treating it as soon as possible is important. When not treated, milder cases of rickets can result in long-term bone damage that can keep bones from growing properly. Severe cases that arent treated can lead to seizures, heart damage and death.

The good news is that thanks to vitamin D-fortified infant formula and fortified cows milk, rickets is very uncommon in the United States.

Sun Exposure During Winter Months

The Ultraviolet Index measures the level of ultraviolet radiation. Throughout winter, particularly in the South Island, the UVI is usually less than 3 .

When the UVI is 3 , skin damage occurs after about an hour in those people with sensitive or fair skin. However optimal vitamin D can still be produced in a few minutes if at least the face, arms and legs are exposed.

NIWA provides a year round daily guide of the UV throughout New Zealand.

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How Do You Know If Youre Vitamin D

Measuring the form of vitamin D made in the liver, called 25-hydroxyvitamin D, is the best way to find out whether you are deficient. Ask your doctor if you should do the blood test to check your 25-hydroxyvitamin D level.

Bone density tests measure how much calcium is in bones. Low bone density signals a condition called osteoporosis. Severe vitamin D deficiency can be a sign of osteomalacia . In children, severe vitamin D deficiency appears as rickets.

What To Know About Vitamin D Toxicity Or Overdosing On Vitamin D

When it comes to vitamin D, more isnt always better. Since the vitamin is fat soluble, its stored inside the body and can be harmful if your levels get too high. Too much vitamin D can cause vitamin D toxicity, or hypervitaminosis D, Clifford says.

You dont have to worry about overdosing if you rely on your diet and sunlight to reach 600 IU a day. Its once supplements get added that it becomes a concern. Its more common with mega doses of supplements taken over a long period of time usually doses above 10,000 IU per day, Clifford says.

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Why We Need Vitamin D

Vitamin D helps you absorb calcium and phosphorus from your diet and use these minerals to keep your bones, teeth and muscles strong. This helps prevent falls as you get older.

Vitamin D may have other roles in the bodys immune system and heart health too.A lack of vitamin D can cause bone problems such as rickets in children and muscle weakness and painful or tender bones in adults.

The Vitamin D Challenge: Getting It From Sunlight

When your skin is exposed to ultraviolet rays from the sun, your body creates its own vitamin D. “When you’re out and about, use sunscreen to cover sensitive areas. But a little bit of sun is good for everybody,” says Dr. Lacey.

Where you live matters. If your home is farther away from the equator , you need to spend more time in the sun to produce enough vitamin D. If you don’t get regular sunlight in the winter months, you may need to increase your dietary intake or take a supplement. CAPTION: Primary care doctor Mindy Lacey, MD, has seen an increase in vitamin D deficiency in the past several years. “If you’re exhausted, your bones hurt and you’re feeling sad, that’s an indication that something may be wrong,” says Dr. Lacey.

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