Can you have too much Vitamin D?

As we are spending more time in our homes, a daily dose of Vitamin D has never been more important to help you and your family stay well.

The main function of Vitamin D in the human body is to regulate our calcium and phosphate levels. If we have good levels of these, then it helps keep our bones, teeth and muscles healthy.

If we don’t get enough Vitamin D, then this can result in some people developing bone deformities.

But, is it possible to have too much Vitamin D?

Where do we get Vitamin D from?

Vitamin D is found in some food, but this is not the primary source of Vitamin D. Human beings get most of the Vitamin D they need from the sun.

The sun acts on chemicals under the skin and helps turn them into Vitamin D. Unfortunately, getting enough Vitamin D daily can be difficult in the UK and in northern climates where people spend a lot of their time indoors (and the weather is not always the best).

Wearing an SPF, which is highly recommended to provide our skin from the sun’s harmful UV rays, can also impact our body’s ability to absorb Vitamin D.

It is also widely reported that it can take people with naturally dark skin longer to boost their Vitamin D levels in the sunshine.¹

The main reason for this is that the pigment (melanin) in dark skin does not absorb as much UV radiation.²

The best Vitamin D-rich foods

Vitamin D is present in a small selection of food. These food sources include:

Oily fish – such as mackerel, herring, salmon, sardines
Liver
Egg yolks
Red meat
Fortified food – such as fat spreads and breakfast cereals
Dietary supplements – while they are not strictly a food, they are consumed and can be used to help boost Vitamin D levels, especially between October to March, when we spend more times indoors, there is less natural sunlight and the sun’s rays are not as strong as in the summer.³

Summary

Vitamin D is made naturally via exposure to the sun
It can also be obtained via animal products such as red meat, oily fish and eggs
Vitamin D can be taken as a supplement

How much Vitamin D do we need?

According to the latest NHS guidance, adults and children over the age of one need 10mcg (micrograms) of Vitamin D per day.

This guidance applies to everybody, including people who are at risk of having a Vitamin D deficiency and women who are pregnant or breastfeeding.

For babies who are up to the age of one, they require 8.5-10mcg of Vitamin D per day.⁴

Calculating Vitamin D levels

When looking at supplements, the UK guidance is in micrograms, but a lot of the labels refer to IU (International Unit) which can be a bit confusing.

To help you out, it is worth remembering that one IU of Vitamin D is equivalent to 0.025 micrograms.

Or you can use this table:⁵

IU	How to calculate	MCG
400IU	Divide by 40	10mcg
600IU	Divide by 40	15mcg
800IU	Divide by 40	20mcg
1000IU	Divide by 40	25mcg
2000IU	Divide by 40	50mcg

The best ways to boost your Vitamin D levels

Here are some food and non-food related ways you can up your Vitamin D levels:⁶

Get out in the sunlight – it is worth noting here that people with darker skin (as mentioned above) need to spend longer in the sun than people with lighter skin to produce Vitamin D. If you’re older, your skin can also be less efficient at producing Vitamin D too.
Up your intake of fatty fish – fatty fish and seafood are among the richest natural food sources of Vitamin D around. A 100g serving of canned salmon can provide up to 386IU of Vitamin D, that’s around half of the recommended daily allowance.
Eat mushrooms – just like humans, mushrooms can produce their own Vitamin D once they are exposed to UV light. Humans produce a form of Vitamin D known as D3 or cholecalciferol, whereas mushrooms produce D2 or ergocalciferol.
Eat egg yolks – not all yolks contain the same Vitamin D levels. But on the whole, research has found that eggs from pasture-raised or free-range chickens offer up to four times more — or up to 20% of the RDA. Interestingly, this depends on how long the chicken has spent outdoors in the sun.
Use a UV lamp – UV lamps mimic the action of the sun and can be especially helpful if your sun exposure is limited because of living in limited sun areas or because you spend quite a bit of time indoors.
Take Vitamin D supplements – supplements vary in dosage and the amount you take in supplement form will depend on your natural Vitamin D levels

Vitamin D intake upper level guidance

To help prevent toxicity, it’s advisable to follow these upper intake levels:⁷

Age	Intake (IU)
0-6 months	1000
7-12 months	1500
1-3 years	2500
4-8 years	3000
9+ years	4000

Can you overdose on Vitamin D?

We all need enough Vitamin D, but it is possible to have too much of a good thing. It is almost impossible to get too much Vitamin D from your diet or from sunlight.

Food sources can only deliver a limited amount of the vitamin, and your body is great at regulating its own Vitamin D. Any extra produced by exposure to sunshine is stored in your body fat.

Many people turn to taking Vitamin D supplements, especially in the winter months when they feel they are not getting enough exposure to sunlight. This is great but it is possible to have too much Vitamin D, so you should be responsible with your approach to supplementation.

The most extreme levels of overdosing on Vitamin D in supplement form is called hypervitaminosis D.

Vitamin D toxicity can lead to a build-up of calcium in your blood (hypercalcemia), which can cause nausea and vomiting, weakness, and frequent urination. In some cases, Vitamin D toxicity can also cause bone pain and kidney problems, such as the formation of calcium stones.

Toxicity is rare, but could be serious. It is easy to avoid: be aware of your supplement’s dose, and only take the recommended daily amount.

Latest Government guidelines from Public Health England suggest 10 micrograms (400 iu) of Vitamin D for adults and children aged 12+ months.

If you stay within these guidelines, you are unlikely to experience any ill-effects. The only caveat to this would be if your body lacks the ability to absorb or utilise Vitamin D.

Summary

It is highly unlikely that you can overdose on Vitamin D via sunlight or diet
It is possible to take too many supplements containing vitamin D, so always follow the dose guidelines

What are the risks of taking too much Vitamin D?

If you were to take too much Vitamin D from a supplement (or from large doses of cod liver oil), you are at risk of high levels of calcium in your blood.

The medical term for this is hypercalcemia. And it could result in nausea and constipation.

It could also affect your mental capacity, leaving you feeling fuzzy-headed and confused. In extreme cases, it could lead to kidney stones.