Can you overdose on vitamins? The myths and the facts

Can you overdose on vitamins? Two myths, both wrong

There are two common beliefs about vitamins. The first: vitamins are natural, and whatever your body doesn’t need, it simply gets rid of. The second: anyone who takes vitamins is quickly putting their health at risk. The truth lies somewhere in between, and it depends on the nutrient and the amount.

Authorities in Europe have assessed where the limit lies for many nutrients. Their figures show the amount above which caution is advised, and where the data so far haven’t been enough to set a firm limit.

Who sets the limits?

EFSA, the European Food Safety Authority, sets tolerable upper intake levels for vitamins and minerals. This is the amount that, according to current knowledge, can be taken every day over a long period, from all sources combined, without harming your health¹.

The German Federal Institute for Risk Assessment (BfR) also proposes maximum amounts per daily dose of a food supplement. It allows for the fact that many people also eat fortified foods, which can push their intake up to high amounts. The proposals are intended as a basis for future rules at EU level¹.

Fat-soluble or water-soluble: why it matters

Whether a vitamin is water-soluble or fat-soluble makes a difference. The body can store fat-soluble vitamins such as vitamin D, so an excess doesn’t disappear overnight. If you take far too much over a long period, you really can overdose.

So stick to the recommended daily amount, and if you take vitamin D in more than one supplement, add the amounts together. Your vitamin D level can be checked with a blood test, so if you take it over a longer period, ask your doctor to do this. If you take any medicines, check with your doctor before you start taking vitamin K.

Vitamin C: what happens to the excess?

For vitamin C, the first myth has a grain of truth in it. In a study with seven healthy volunteers, the body fully absorbed a single dose of 200 mg. From single doses of 500 mg upwards, the proportion absorbed fell, and the body excreted what it had absorbed in the urine².

EFSA was unable to set a tolerable upper intake level for vitamin C because there weren’t enough data. It did, however, assume that an extra 1,000 mg a day on top of a normal diet is not linked to digestive complaints³. The BfR recommends no more than 250 mg of vitamin C per daily dose for food supplements³.

Vitamin B12: can you have too much?

For vitamin B12, no harmful effects on health have been found so far from which an upper limit could be derived. That’s why there’s no tolerable upper intake level⁴. The BfR considers that healthy people in the general population get enough vitamin B12⁴.

You can read about the different forms of vitamin B12 in our article Which vitamin B12 is right for you?

Omega-3: how much is considered safe?

Omega-3 fatty acids aren’t vitamins, but the question of how much is too much applies just the same. For the fatty acids EPA and DHA, the data weren’t sufficient for EFSA to set a tolerable upper intake level. According to its assessment, however, up to 5 g a day of EPA and DHA combined, taken as a supplement, is safe for adults⁵. At Melinava, you’ll find omega-3 fatty acids in our Omega 3.

It’s the total that counts

Many people take more than one supplement. According to data from the German National Nutrition Survey, 7.4% of those surveyed took two vitamin C supplements on the survey days³. That’s how amounts add up without anyone noticing.

• Check whether a nutrient appears in more than one of your supplements, for example in a multivitamin and a single-nutrient supplement.
• Remember fortified foods such as juices or breakfast cereals.
• If you take any medicines, check with your doctor first.

Do not exceed the recommended daily amount. Whether it makes sense to take supplements long term is covered in our article Should you take supplements continuously or take breaks?

‘You can’t overdose on vitamins’? Our verdict: false

The claim ‘you can’t overdose on vitamins’ is false. With some nutrients, such as vitamin D, an overdose is possible; with others, such as vitamin B12, no harm has been shown so far. If you stick to the recommended amount and keep an eye on the total from all your supplements, you’ve already done the most important thing.

Frequently asked questions about vitamin overdose