Vitamin B12 deficiency symptoms: What colour are your nails? Sign you're lacking B12

Vitamin B12 deficiency symptoms can develop if a person lacks the vitamin from their diet. Vegans and vegetarians stand risk of becoming deficient in B12 because the best sources of the vitamin are from foods of an animal origin. Certain medical conditions can also affect a person’s absorption of vitamin b12 from foods, such as pernicious anaemia. Vitamin B12 plays an important role in the production of red blood cells and keeping nerves healthy, so if a person lacks B12, their red blood cell count will be lower and their nerves risk becoming damaged.

Other complications can occur if vitamin B12 deficiency is left untreated, including loss of physical coordination and heart failure.

These complications can be avoided by spotting vitamin B12 deficiency early, and one symptom of the condition to be aware of is having bluish- black coloured nails.

According to research published in The Journal of Family Practice in 2012, vitamin B12 deficiency can affect nails by turning them entirely blue, or causing blueish-black pigment with “wavy longitudinal dark streaks, brownish network like pigmentation and longitudinal darkened streaks”. 

The researchers also noted these nails changes were reversible, and resolved with B12 supplementation therapy.

As well as red blood cell production, vitamin B12 plays a role in iron absorption.

Both iron and B12 are necessary for keeping nails strong and healthy.

This is why vitamin B12 deficiency can also cause nail fungus.

According to the Health Science Journal, vitamin B12 is important when it comes to treating brittle nails that may break easily.

It adds: “Lack of this vitamin may cause toenail fungus and other similar infections as the nails are prone to these conditions.

“In addition, nails may turn dark when the body does not get enough vitamin B12.”

Other symptoms of vitamin B12 deficiency

Other symptoms of the condition are listed by Bupa as:

  • Feeling very tired
  • Breathlessness even after little exercise
  • Heart palpitations
  • Headaches
  • A reduced appetite
  • A sore mouth and tongue

The health organisation adds: “If you have vitamin B12-deficiency anaemia, you may also look pale or jaundiced (have a yellowy tinge to your skin and the whites of your eyes).

“As well as the symptoms of anaemia, vitamin B12-deficiency may cause symptoms related to your nerves. This is called vitamin B12 neuropathy. It may affect your movement and sensation, especially in your legs, cause numbness or pins and needles and decrease your sensitivity to touch, vibration or pain. It can also cause confusion, depression, poor concentration and forgetfulness.

“These symptoms aren’t always due to vitamin B12-deficiency anaemia, but if you have them see your GP.”

Treatment for vitamin B12 deficiency

If a person isn’t getting enough vitamin B12 from their diet they may be advised by a GP to eat more foods fortified with vitamin B12 or to take regular supplements.

Vitamin B12 injections may also be recommended, and for those with pernicious anaemia, injections may be required for the rest of their lives.

Experts say adults aged 19 to 64 require around 1.5 micrograms a day of vitamin B12, and unless you have pernicious anaemia, you should be able to get this through your diet.

If vitamin B12 deficiency is triggered by not including enough B12 foods in the diet, Harvard Health Publishing, part of Harvard Medical School, offers the “A list of B12 foods” on its website


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