Too Much Vitamin D: Is It Possible?

    Updated 02 April 2019 |
    Published 29 March 2019
    Fact Checked
    Reviewed by Kate Shkodzik, MD, Obstetrician and gynecologist
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    Despite the fact that vitamin D is important for the maintenance of the skeletal system, it’s not readily available to the body through the diet. Few foods provide this important vitamin. So how do you get vitamin D?

    What is vitamin D?

    Your skin has the ability to convert sunlight into vitamin D. Every time you step out into the sunlight, your skin is making vitamin D.

    But many people also opt for supplements in order to get enough vitamin D. However, by doing this, you risk putting too much of the vitamin into your body. In this article, we’ll look at how much vitamin D is too much. We’ll also cover the symptoms and side effects of too much vitamin D and what to do when you ‘overdose’ on the vitamin.

    Before we wade into this topic any further, let’s first find out what exactly vitamin D is. Vitamin D is a fat-soluble vitamin that plays an integral role in the regulation of calcium and phosphorus in the body — and therefore in bone development, as well as muscle and nerve function. It only appears naturally in a few foods, including fatty fish and fish oils. You can also find smaller amounts in egg yolk, beef liver, and cheese.

    The most common source of the vitamin is from exposure to sunlight. When you expose your skin to the sun, it begins to make an inert form of the vitamin. Further processing in the liver and the kidney will deliver the final active form of vitamin D, which is what the body needs for various bodily processes.

    Understanding a vitamin D overdose

    A vitamin D overdose is when you take in too much vitamin D. But you might be wondering, “Can you take too much vitamin D?" Yes, you can. Since there’s only so much of the vitamin you can naturally take in from your diet and through your skin, an overdose is likely to be from dietary supplements containing the vitamin.

    In areas in the northern hemisphere, there are days when the sun doesn’t come out. There are also, of course, people who spend most of the day indoors or sleeping, like office workers and workers on the night shift. These people don’t get enough vitamin D through exposure to the sun’s ultraviolet light.

    If you’re an adult, the recommended dietary allowance (RDA) of vitamin D shouldn’t exceed 600 international units (IU) in one day. More than this can cause vitamin D toxicity and its associated effects in the body.

    Symptoms of too much vitamin D

    Generally, when you have consumed too much vitamin D, you’ll experience symptoms that will let you know that all is not well in your body. These vitamin D overdose symptoms are mainly the result of too much calcium accumulating in the blood — a condition known as hypercalcemia.

    The symptoms include:

    • Increased thirst
    • Frequent urination
    • Loss of appetite
    • Nausea and vomiting
    • Fatigue
    • Disorientation and confusion
    • Persistent headache
    • Dry mouth

    Vitamin D side effects 

    When it comes to vitamin D, it’s almost always easier to find someone with a deficiency than one with an overdose. However, there are rare cases of people with too much vitamin D in their systems. These present with various side effects, including:

    • Hypercalcemia

    This is the most common side effect of too much vitamin D. It’s a condition where there is too much calcium in your bloodstream, which places stress on the digestive tract. This can manifest as nausea, vomiting, and a tummy ache. You will also feel thirsty and urinate frequently.

    • Compromised bone structural integrity

    Too much vitamin D in the body reduces the amount of vitamin K, which is responsible for keeping calcium bound in the bone structure. If vitamin K is lacking, it will cause the bones to lose calcium, making them weaker.

    • Kidney failure

    When you take too much vitamin D, your kidneys may not be able to work optimally and are at risk for ultimately failing. The elevated calcium levels brought about by the high vitamin D levels can harden the tubules in the kidney, causing kidney stones. Kidney stones are extremely uncomfortable and can interrupt your sleep with a strong pain in your lower back and abdomen.

    Vitamin D overdose treatment 

    If you find out that you have a vitamin D overdose, it’s recommended that you stop taking your vitamin D supplements as soon as possible. The signs and symptoms of the overdose might take a while to subside because vitamin D is stored in fat and doesn’t leave the system immediately.

    Your doctors might also recommend that you cut calcium from your diet while they monitor the levels in the blood. This cuts down the hypercalcemia until your calcium levels return to normal.

    In some instances, your doctor may prescribe corticosteroids and bisphosphonates, which will prevent the release of more calcium from your bone structure. Your doctor can also give you oral calcium disodium edetate, which increases your ability to pass calcium through feces.

    How much vitamin D to take

    There are few foods containing vitamin D that you can naturally add to your diet. Therefore, you have to resort to dietary supplements to increase the amount of vitamin D in your body. 

    Nutritionists and scientists have not agreed on an amount of the vitamin that is just enough for the body. What they do agree on is that if you exceed a certain amount of the vitamin, you will experience unpleasant side effects.

    They recommend only 1000 IU to babies under the age of six months. Those who are between 7 months and a year old can only tolerate 1500 IU of vitamin D. Toddlers from age 1 to 3 years shouldn’t exceed 2500 IU, whereas children from 4 to 8 years should have a maximum of 3000 IU of vitamin D.

    From 9 years onwards into adulthood, the highest tolerated intake of vitamin D is 4000 IU. Intake past these recommended amounts will likely result in the undesirable symptoms mentioned above. 

    Vitamin D is a critical vitamin for the body, and it’s important to remember that too-low levels can also put you at risk for negative health effects. The best course of action is to get your vitamin D levels tested (which can be done with a simple blood test) and talk to your doctor about how to safely increase your vitamin D intake, if necessary.

    History of updates

    Current version (02 April 2019)

    Reviewed by Kate Shkodzik, MD, Obstetrician and gynecologist

    Published (29 March 2019)

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