Vitamin B12 for PCOS: 7 signs of deficiency

You may have read about the link between PCOS and vitamin B12, in particular for people with PCOS taking metformin. In this article we are discussing what PCOS and vitamin B12 are, the link between the two plus food sources, dosage and supplementation.

Keep reading to learn more about vitamin B12 for PCOS.

What is PCOS?

Polycystic ovary syndrome (PCOS) is an endocrine condition with metabolic and reproductive consequences. Whilst there are multiple symptoms including; irregular periods, difficulty getting pregnant, excessive hair growth, changes in weight, thinning hair on the head and acne.

What is vitamin B12?

Vitamin B12 is a water-soluble vitamin also known as cobalamin. Vitamin B12 has many vital functions in the body. It is fundamental for the metabolism of fatty acids and amino acids, for normal blood formation and neurological function. It is also required for the use of folate.

What are good sources of vitamin B12?

There are some food sources of vitamin B12 including meat, fish, dairy and eggs. Some food products are also fortified with B12 such as breakfast cereals.

Can PCOS cause B12 deficiency?

A lack of vitamin B12 can lead to vitamin B12 deficiency anaemia. So, it is important to be aware of the symptoms of deficiency and the drivers of deficiency.

Although more research is required to understand the link, a study found that concentrations of B12 were lower in people with PCOS with insulin resistance than those without.

Metformin and B12 deficiency

A commonly recommended medication for individuals with PCOS is insulin-sensitiser metformin. However, research has shown that long-term use of metformin at high doses can deplete levels of vitamin B12.

One of the largest studies investigating the link between metformin and vitamin B12 was through the diabetes prevention programme, concluding long-term use of metformin was associated with B12 deficiency and anaemia.

Unfortunately, studies specifically looking at metformin use in individuals with PCOS are less common. However, a systematic review and meta-analysis looking at individuals with PCOS and individuals with type 2 diabetes found the higher the dose of metformin the more deficient individuals were in vitamin B12.

If you take metformin your doctor or healthcare provider should regularly test your blood to check for B12 deficiency. You will need to take B12 supplements or injections to prevent vitamin B12 deficiency anaemia.

Folic acid and B12 deficiency

Taking a folic acid supplement is often recommended for those trying to conceive. But, it is important to be aware of the link between folic acid and vitamin B12 deficiency.

Taking too much folic acid (over 1 mg per day) can mask symptoms of a B12 deficiency. So, if you are vegan or vegetarian and/or take metformin, it is important to regularly get your B12 levels checked by your doctor.

7 signs of vitamin B12 deficiency

If you think you may be at risk of vitamin B12 deficiency and are experiencing any of the below symptoms it is important to consult with your healthcare professional:

Extreme tiredness

A constant feeling of tiredness and exhaustion can often indicate deficiency. B12 aids in releasing energy and consequently tiredness is a symptom of not having enough energy.

Pins and needles (tingling in your hands or feet)

This is also called paraesthesia. A regular occurrence of getting pins and needles is a warning sign of a deficiency.

Problems with memory, understanding and judgement

Due to the vitamins’ role in supporting the nervous system, deficiency can often affect mental or neurological function

Feeling weak

You may feel weak and lightheaded regularly, even from everyday activities. B12 is linked to red blood cells so your heart has to work harder causing feelings of weakness.

Disturbed vision

A deficiency of B12 can cause damage to the optic nerve. This can cause blurred or double vision, sensitivity to light and, in severe cases, even vision loss.

Pale or yellow skin

A change in skin colour (e.g. yellow or discoloured) can also be a sign you are not getting enough B12.

Mouth ulcers

The development of mouth ulcers is not only uncomfortable but can also be a sign of a deficiency.

Treating B12 deficiency

B12 deficiency can be treated or prevented by supplementing with tablets or injections.

Vitamin B12 dosage for PCOS

In the UK, adults require 1.5 micrograms daily of vitamin B12 but the vitamin B12 dosage for PCOS increases if someone is taking metformin. Speak to your healthcare professional about supplementing with B12 as you can take supplements or receive a B12 injection from a certified healthcare professional.

Also, if you don’t consume meat, dairy, fish or eggs then taking a supplement may be suitable for you.

Best B12 supplements for PCOS

Nutravita Vitamin B12 1200mcg
£9.99 (£0.03 / count)

Capsule/tablet form

  • Vegan
  • Easy to swallow
  • 365 tablets
  • 1200 mg
We earn a commission if you make a purchase, at no additional cost to you.
06/17/2024 12:55 pm GMT
BetterYou Boost Vitamin B12 Daily Oral Spray
£11.95 £7.59 (£303.60 / l)

Spray vitamin B12 spray

  • Vegan
  • Easy to swallow
  • 48 daily servings
  • 1200 mg (per 4 sprays)
We earn a commission if you make a purchase, at no additional cost to you.
06/18/2024 12:45 am GMT

B12 supplement side effects

More evidence is needed to understand the effects of too much vitamin B12 on the body. Injectable vitamin B12 (which is used by healthcare professionals to treat severe deficiency) may cause the following mild to moderate side effects:

  • diarrhoea
  • itching and a skin rash
  • headache
  • dizziness
  • nausea and vomiting

There may be further serious side effects such as vein thrombosis, polycythemia vera and pulmonary oedema or severe allergic reactions. This is why it is essential to only have B12 injections from doctors or other healthcare providers.

Annabel Sparrow ANutr Author at The PCOS Collective

Author | Registered Associate Nutritionist


Annabel is a Registered Associate Nutritionist and pilates teacher with an interest in gut health and pre-and post-natal nutrition. She has a BSc degree in Psychology and is passionate about building healthy relationships with food and understanding the connection between food and mood.

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