IBS, B12 and folate deficiency

   21/10/2025

If you have had IBS for a while, you could potentially find yourself with vitamin B12 and folate deficiency. This is particularly worth checking on, as B12 and folate deficiency can actually mimic – or worsen your IBS symptoms.

If you have irritable bowel syndrome, especially long-term or chronic IBS symptoms, you may develop vitamin and mineral deficiencies. This can happen either because eating a varied diet isn’t possible, or because your gut health or meds are impairing absorption of them. Vitamin D, vitamin C and iron are often mentioned as being low in IBS sufferers.

However, vitamin B12 and B9 (folate) deficiency can actually create what look like IBS symptoms, or worsen your physical and/or neurological health.

Awareness is key. So read on, and get this checked out by your doctor.

Symptoms of IBS, vitamin B12 and folate deficiency

Folate is used for the healthy development and growth of cells (including red blood cells) and DNA synthesis. While Vitamin B12 maintains healthy red blood cells, nerves, nervous system and brain function.

Vitamin B12 and folates also work together and play an essential role in iron absorption.

I have been researching these vitamin deficiencies for my daughter who is vegan. And I was surprised at what I discovered related to IBS and folate deficiency.

According to the NHS website, symptoms of Vitamin B12, or folate (B9) deficiency anaemia include:

  • diarrhoea
  • indigestion
  • mild depression
  • anxiety
  • feeling weak or tired
  • loss of appetite
  • headaches

The clients that I coach often have some of these symptoms. And while these symptoms can also be related to IBS and emotional triggers, B12 and folate deficiency is reported to actually cause the listed symptoms too. So it’s worth knowing about!

IBS and B12 deficiency

IBS and vitamin B12 deficiency

Vitamin B12 is found in meat, fish and dairy products.

Which is why vegans in particular have to supplement their diet or find alternatives like breakfast cereals and soya drinks that are fortified with B12, and yeast extract.

The recommended daily intake (RDA) of B12 for adults is 2.4 – 2.8 micrograms.

People with gastrointestinal disorders, and those who have had gastrointestinal surgery are more likely than others to be vitamin B12 deficient.

In addition to supplements, vitamin B12 deficiency can be treated with injections directly into the blood stream if needed. That way there is no need to digest food first.

Folate deficiency (B9)

The RDA of vitamin B9 in adults is 400 micrograms per day.

Folates can be found in vegetables like kale, broccoli, Brussels sprouts, spinach, chickpeas, lentils, beans, asparagus, peas, as well as brown rice and fortified grains.

IBS and folate deficiency

If you are experiencing IBS and have folate deficiency, it could well be that you find most of these foods difficult to digest. And there is no point forcing them.

There is the option of taking folic acid supplements – if you can digest them.

This is where you will need specific guidance and regular testing from your healthcare provider.

According to leading endocrinologists, Vitamin C can improve folic acid absorption by helping it remain stable in the digestive tract. They also say that foods fortified with B9 take one step out of the assimilation process. However, antacids that are commonly used for indigestion may actually decrease absorption of folates.

It has been intriguing to discover a study showing that folic acid attenuates chronic visceral pain in rats. I wonder what it could do for abdominal pain in IBS sufferers

A special mention for thyroid problems

Understanding the potential connections between IBS and folate deficiency might also shed light on thyroid issues that many IBS suffers face.

A number of studies are linking low, if not deficient levels in B12 and folates to hyperthyroidism and hypothyroidism. If you are concerned, this insightful article gives more details and guidelines.

Where to go from here

If you suspect you might be deficient in these vitamins, it would be wise to get a blood test done periodically. Ask your doctor’s or nutritionist’s advice on supplementing while you have IBS symptoms.

This article is for informational purposes only. Alison Adenis has written this article based on her own research. She is not a doctor or nutritionist.