Vitamin D is fat-soluble. What you take in excess is not passed in urine, as with vitamin C, but stored by your body. That is why supplements can build up too much vitamin D over time. Sunlight and food cannot. Below you can read how much vitamin D you need per day, where the upper limit lies, which symptoms belong to an excess and what to do if you are in doubt.
How much vitamin D per day?
The recommended daily amount is 10 micrograms of vitamin D a day. That applies to everyone from birth. Only people aged 70 and over need 20 micrograms a day. These figures come from the Dutch Health Council and are also listed by the Netherlands Nutrition Centre.
Most of your vitamin D is made in your skin under the influence of sunlight. From March to October, fifteen to thirty minutes outside each day with your face and hands uncovered is enough for most people to reach 10 micrograms and build up a reserve for winter. For some groups that is not enough. For them a supplement is advised:
- Children aged 0 to 3: 10 micrograms
- Everyone aged 4 to 69 with darker skin, or who spends little time outdoors during the day: 10 micrograms
- Women aged 50 to 69: 10 micrograms
- Pregnant women: 10 micrograms
- Everyone aged 70 and over: 20 micrograms
Labels often show IU (international units) instead of micrograms. The conversion is simple: 1 microgram is 40 IU. So 10 micrograms is 400 IU, 25 micrograms is 1,000 IU and 75 micrograms is 3,000 IU.
How much vitamin D is too much?
The European Food Safety Authority, EFSA, has set a tolerable upper intake level. That is the amount you can take in day after day, from food and supplements combined, without problems being expected:
- Up to 1 year: 25 micrograms a day
- 1 to 10 years: 50 micrograms a day
- 11 years and older: 100 micrograms a day
On top of that, Dutch food law sets a maximum for what a supplement may contain: 15 micrograms for babies under 1, 20 micrograms for children aged 1 to 10 and 75 micrograms for everyone from 11 years. That limit is deliberately below EFSA’s upper level, because you also get vitamin D from food and sunlight.
A supplement with 75 micrograms (3,000 IU) is therefore a high dose, but one that falls within the Dutch rules. That does not mean everyone needs that much. For most adults 10 micrograms is the advice. A higher dose is something to discuss with your GP, for instance after a blood test that shows a deficiency.
Symptoms of too much vitamin D
Vitamin D makes sure you absorb calcium from food. With a prolonged excess, the calcium level in your blood rises. That is called hypercalcaemia, and that is where the complaints come from. Recognisable signals are:
- Stomach and bowels: nausea, vomiting, little appetite, stomach ache and constipation.
- Thirst and frequent urination: your body tries to get rid of the extra calcium through the kidneys.
- Tiredness and muscle weakness: you feel weak, even after a good night’s sleep.
- Confusion or dizziness: with a serious excess.
These complaints are not specific. They belong to dozens of other causes too. So the most important signal is not a symptom, but the combination of complaints with a high dose of vitamin D that you have been using for some time.
With large amounts over a long period, calcium deposits can form in the body. That can lead to kidney stones and kidney damage. With a normal diet and by following the intake advice, this is not a danger.
Side effects of vitamin D at a normal dose
At 10 to 25 micrograms a day no side effects are to be expected. The complaints above belong to an excess built up over weeks to months, usually with doses far above the advice. If you do notice complaints after starting a supplement, the cause is more often something else: the fillers in the product, taking it on an empty stomach, or another supplement you take at the same time. Stop the supplement and consult your GP or pharmacist if the complaints persist.
When do you take in too much vitamin D?
Really only through supplements. Through the sun an excess is impossible, because your skin slows down production itself. Through food it is not realistic either: a 100 gram piece of salmon provides 4.6 micrograms, an egg 0.9 micrograms.
An excess arises when you take more than the upper limit for a longer period. That happens, for instance, when you stack several supplements that all contain vitamin D, such as a multivitamin plus a separate vitamin D supplement plus a fish oil with vitamin D. If in doubt, add up the labels. In practice an overdose of vitamin D is rare in healthy people.
Vitamin D3 or D2?
Supplements contain vitamin D2 (ergocalciferol) or vitamin D3 (cholecalciferol). D3 is the form your skin makes itself and traditionally comes from animal sources, but is these days also available plant-based, from lichen. For an excess the form makes no difference: the same upper limits apply to both.
Vitamin D and vitamin K2
Vitamin D and vitamin K2 are often combined in one capsule. That is because both have an approved claim about bones: vitamin D contributes to the maintenance of normal bones, and so does vitamin K. Both are fat-soluble, so you preferably take them with a meal containing some fat. You can read more about what you can and cannot take together in our guide which vitamins can you take together.
If you want both in one product, have a look at the vitamin D3 and K2 capsules by Together. If you prefer a low dose, a separate vitamin D3 supplement makes more sense. Always check the dose on the label.
What do you do if you think you have too much vitamin D?
Stop the supplement and call your GP. They can order a blood test. It measures the value 25-hydroxyvitamin D, together with the calcium in your blood. Your GP interprets that result; a number on its own says little, because the threshold differs per laboratory and per situation. Because vitamin D is stored in your body, a value that is too high does not drop in a few days. Count on weeks to months.
Seek help immediately with serious complaints such as persistent vomiting, severe thirst with frequent urination or confusion.
Frequently asked questions about too much vitamin D
How much vitamin D per day is too much?
For everyone from 11 years, EFSA’s tolerable upper level is 100 micrograms (4,000 IU) a day, from food and supplements combined. In the Netherlands a supplement may contain at most 75 micrograms. The recommended amount is much lower: 10 micrograms, and 20 micrograms from the age of 70.
What are the symptoms of too much vitamin D?
Nausea, vomiting, little appetite, constipation, thirst, frequent urination, tiredness and muscle weakness. With a serious excess also confusion. The cause is a calcium level in the blood that is too high.
Can you get too much vitamin D from the sun?
No. Your skin regulates production itself and stops when there is enough. Even long periods in the sun carry no risk of an excess. They do carry a risk of sunburn, so you watch that for other reasons.
Is 3,000 IU of vitamin D a day too much?
3,000 IU is 75 micrograms, exactly the maximum a supplement may contain in the Netherlands. It is below the upper level of 100 micrograms, but far above the advice of 10 micrograms. Only take such a dose in consultation with your GP, for instance with a proven deficiency.
How long does it take for too much vitamin D to leave your body?
Vitamin D is fat-soluble and is stored. A blood value that is too high therefore does not drop in days, but in weeks to months after stopping. Your GP can follow that with a repeat blood test.
What is the difference between micrograms and IU?
1 microgram of vitamin D is 40 IU (international units). 10 micrograms is 400 IU, 25 micrograms is 1,000 IU, 75 micrograms is 3,000 IU and 100 micrograms is 4,000 IU.
