Dr Gareth

Medically reviewed by GP Gareth James MBBS, DFFP, DRCOG, MRCGP on December 2, 2023. To give you technically accurate, evidence-based information, content published on the Check My Body Health blog is reviewed by credentialed professionals with expertise in medical and bioscience fields.

Vitamin D is essential for strong bones, a healthy immune system, and more. While some people experience constipation as a side effect of taking high doses of vitamin D supplements, the exact link isn’t fully established. Constipation can be caused by various factors, including dehydration, other supplements, or underlying health conditions. It’s best to consult your doctor if you’re concerned about vitamin D and digestive issues.

What is Vitamin D?

Vitamin D is a fat-soluble vitamin that plays a vital role in several key bodily functions. There are two primary forms of vitamin D: vitamin D2 (ergocalciferol) and vitamin D3 (cholecalciferol). Vitamin D2 is found in some plants and fungi. While vitamin D3 is primarily synthesised in the skin in response to exposure to ultraviolet B (UVB) rays from the sun. Both forms can be obtained from dietary sources and supplements

Why is Vitamin D important?

Vitamin D is like the body’s helper that does some really important jobs.

First, it makes sure our bones and teeth stay strong. It works with calcium and phosphorus, which are like the building blocks for our bones.

But that’s not all – Vitamin D also helps our immune system, which is like our body’s defense team. It makes sure we can fight off germs and stay healthy.

And here’s the cool part: our body can make Vitamin D when our skin gets sunlight. So, spending some time outdoors in the sun is like giving our body a boost of this important vitamin.

What Are the Side Effects of Too Much Vitamin D?

Having too much Vitamin D can only occur if you are taking too man high dose Vitamin D supplement, and may lead to problems if the supplements are not stopped.

One issue is too much calcium in our blood. It’s like having too many workers for our bones, and things can get messed up. This might make us feel really tired, give us stomach problems, or even hurt our kidneys.

Our body sometimes tells us it’s got enough Vitamin D by making us feel sick. Like having a stomachache or headaches. It’s like a signal to stop taking in more Vitamin D.

So, while Vitamin D is good for us, we need to be careful not to get too much. It’s all about finding the right balance.

Why Might Vitamin D Cause Constipation?

Constipation is generally affected by things like what we eat, how much water we drink, how active we are, and how healthy we are.

While there’s limited proof directly saying vitamin D can cause constipation, some people think vitamin D supplements might make you constipated.

Here are some reasons why some people might feel this way:

Too much calcium: Vitamin D helps absorb calcium in our guts. Too much calcium can lead to constipation. So, if vitamin D pills make us absorb a ton of calcium, it might cause constipation for some.

Not enough movement: Vitamin D helps our muscles work, and if we don’t have enough, our muscles might get weak. Not moving around a lot can also lead to constipation.

Do Vitamin D Supplements Cause Constipation?

Similar to the above, some people think vitamin D supplements might make you constipated. There’s not a lot of strong proof for that. Constipation is affected by things like what we eat, how much water we drink, how active we are, and how healthy we are. There is strong study evidence pointing to low vitamin D levels causing functional constipation.

Constipation may be more likely when taking high-dose vitamin D supplements compared to obtaining vitamin D from dietary sources. Supplements deliver a concentrated amount of vitamin D all at once, potentially overwhelming the body’s ability to process it efficiently. Foods containing vitamin D often come with fibre and other nutrients that support healthy digestion.

Are there other vitamins that might contribute to constipation

Like vitamin D, some other vitamins could play a role in constipation. Though it’s not always clear-cut.

Certain types of iron supplements, often found in multivitamins, will cause constipation in some people.

Calcium supplements, similar to the calcium interaction with vitamin D, can sometimes lead to constipation when taken in excess. It’s like our body’s way of saying, “Hey, let’s not have too much of a good thing.”

Remember, everyone’s body is different. So, what affects one person might not affect another in the same way. If you’re ever concerned about vitamins and how they might be influencing your digestion, it’s a good idea to chat with a healthcare professional.

Individual Factors

Several factors can impact a person’s susceptibility to constipation while taking vitamin D supplements. Age can play a role, as older adults may have naturally slower digestion. Certain medications can interact with vitamin D or independently cause constipation. Additionally, a person’s gut microbiome health influences digestive processes, and imbalances can increase the likelihood of constipation.

How to test your Vitamin D levels?

If you think you might not have enough vitamin D or are thinking about taking vitamin D pills getting a test is a good idea. The most common test checks your vitamin D levels in your blood. They look at something called 25-hydroxyvitamin D [25(OH)D], and it shows how much vitamin D you have overall.

Having Vitamin D levels under 25 ng/mL can be harmful to your body, leading to unpleasant symptoms such as joint pains and weakness it can also increase your chance of breaking bones. You would be best to contact your GP surgery under 25 ng/mL as you will probably need a prescribed course of high dose Vitamin D supplement for 6 weeks and possible ongoing long-term supplementation.

Levels between 25 and 50 may require more sunlight exposure, or vitamin D supplementation.

But anything above 50 ng/mL is good.

What Foods Help You Get Enough Vitamin D?

Ensuring an adequate intake of vitamin D can involve incorporating specific foods into your diet. The best way to make Vitamin D is sun exposure, even if overcast, 10 to 15 mins a day (up to double  if you have darker pigmented skin).

Here are some good food options:

  • Fatty Fish: Rich sources of vitamin D are found in oily fish especially those you consume with the bones in them (sardines, pilchards).
  • Egg Yolks: The yolk of eggs is a natural source of vitamin D, enhancing dietary intake.
  • Mushrooms: Certain varieties of mushrooms can synthesise vitamin D when exposed to sunlight, contributing to the dietary supply of this essential nutrient.
  • Fortified Foods: Some food products, such as select types of milk, orange juice, and breakfast cereals, undergo fortification, a process where extra vitamin D is added to enhance nutritional content.

By incorporating these foods into your diet, you can support the body’s vitamin D requirements, promoting overall health and well-being.

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