Do you have a vitamin B12 deficiency? Here are the symptoms to look out for

Vitamin B12 deficiency can be serious, these are the symptoms to look out for

Two whole white eggs on light pink background to represent what to eat if you have a vitamin B12 deficiency
(Image credit: Getty Images)

It's not typical to think of a possible vitamin B12 deficiency when you're feeling tired, scatter-brained, and lethargic unless you've been diagnosed with one before. Despite the plethora of information available around it, it's not a deficiency that's widely warned about.

Instead, we revert to what we know. Feeling tired? Must be too many sleepless nights or a lack of iron. Marching from one room to another, only to discover you've forgotten the reason you went in there? Most of us will put it down to a lack of concentration or age. Feeling tearful for no apparent reason? PMS has a lot to answer for, but it may not be that this time.

Having low levels of vitamin B12 is a relatively easy nutrient deficiency to treat, but if left unchecked, it can lead to more serious health conditions - including those affecting the nervous system.

What is vitamin B12?

Vitamin B12 is a water-soluble essential vitamin. It's naturally found in foods like animal products and added to others, like plant-based milk alternatives, explains Signe Svanfeldt, nutritionist at Lifesum (opens in new tab)

Unlike some others, vitamin B12 can't be produced by the body and must be consumed via food. To stay healthy, we need around 1.5 to 2 micrograms per day. If you're breastfeeding then the recommendation is slightly higher at 2.5 micrograms every day. "But this is easily achievable by eating two large eggs or 150g of cod," she says. 

Other foods rich in vitamin B12 are usually animal based, explains Dr Thom Phillips from Forth (opens in new tab). "These include red meat, poultry, milk and yogurt," he says. "You can increase your intake by increasing levels of this food in your diet or by choosing a good quality supplement."

Why do we need vitamin B12?

Vitamin B12 is required to complete many of the body's natural processes, Dr Phillips explains. "It works with folate [folic acid when man-made] and vitamin C to help the body make new proteins and it's crucial for making red and white blood cells, repairing cells, and synthesizing new DNA," he says.

It also mirrors the benefits of vitamin D in many ways, as a lack of vitamin B12 is associated with lower mood and changes in brain function thanks to a lower level of serotonin production. 

In years gone by, a study by the University of Sydney (opens in new tab) explains, a deficiency was only thought to develop after several years and only in those with pernicious anemia, or those following a strict vegetarian diet. Newer research suggests otherwise though, and it's entirely possible to develop this serious condition just by not getting enough of the essential vitamin. 

Woman holding up a pot of soft cheese to check nutritionals after being diagnosed with vitamin B12 nutrient deficiency

(Image credit: Getty Images)

Symptoms of a vitamin B12 deficiency 

1. Pale tinge to the skin

Those who are experiencing a vitamin B12 deficiency may notice their skin start to turn a pale shade of yellow. "This is a condition called jaundice," explains Melanie King, a pharmacist at Pharmacy2U (opens in new tab). "It happens because a B12 deficiency causes more red blood cells to be broken down." 

When this happens, she says, a waste product is a process called bilirubin is produced which causes the skin yellowing.

2. Sore, red tongue

If you notice any changes in the shape or appearance of your tongue, or you experience tongue pain, you should immediately see a doctor as this is one of the biggest signs of a vitamin B12 deficiency. 

"The tongue can appear bright red in patches and can also change shape and become painful," King says. "This happens in about 1 in 4 of B12 deficiency cases."

3. Changes to your vision

Finding that your eyesight is getting worse is a natural part of growing older, unfortunately, but if you've noticed significant changes over a short period then it's worth considering a vitamin B12 deficiency as the cause. 

"A deficiency in vitamin B12 can cause damage to the optic nerve and lead to a blurring of vision," King says. "Sometimes the perception of color can be affected too."

4. Change in neurological abilities

Memory, understanding, and judgment are all impacted by our vitamin B12 levels - even though why that is isn't fully understood. 

"It's thought that B12 vitamins are needed by the body to make the mood chemical serotonin," says King. This is also the main reason why studies, including one by the California Institute of Behavioral Neurosciences & Psychology (opens in new tab), have linked the deficiency with higher rates of depression. 

"A cognitive decline caused by a deficiency can be reversed with B12 treatment, but giving extra B12 doesn't treat cognitive decline caused by other factors," she adds. 

Another reason for changes in cognitive behavior is that B12 affects your nervous system - which includes the brain. "This manifests in symptoms like pins and needles, and you may notice changes in the way that you walk and move around," King adds. "You might also develop problems with your vision and speech."

5. Anemia

Almost 30% of women have officially been diagnosed with anemia, which is when you have fewer red blood cells or a lower level of hemoglobin in each blood cell than normal. This works out to over half a billion women aged between 15 and 49 years old, according to the World Health Organisation (opens in new tab) (WHO).

There's a reason we often link a lack of iron with tiredness as it's one of the most common causes, but vitamin B12 deficiency is another cause of the condition. 

"If that's the case," King says, "You might also experience additional symptoms such as fatigue, lethargy, feeling faint, headaches, pale skin, heart palpitations, a loss of appetite, and weight loss."

How serious is a vitamin B12 deficiency?

It's important to get help for a B12 deficiency if you are diagnosed with one, King says. "Many of the symptoms of vitamin B12 deficiency can be treated and are reversible if caught early. However, the longer it is left untreated, the higher the risk of permanent damage," she explains. 

"Alongside neurological changes, other long-term effects can include fertility issues, and an increased risk of stomach cancer if your deficiency is caused by pernicious anemia. This is a condition where the immune system attacks the cells in the stomach that absorb vitamin B12." For these reasons, it's best to seek medical help instead of treating the condition yourself.

When to see a doctor

A vitamin B12 deficiency can occur for several reasons, lead to serious issues, and can be part of a wider health issue, so if you are experiencing any of the symptoms - or a combination of them all - then it's important to visit your doctor as soon as possible. 

"Some may experience difficulties absorbing vitamin B12 from their diet for various reasons, including medication, disease, or age as the ability to absorb vitamin B12 decreases with age and the onset of perimenopause symptoms," Svanfeldt says. 

"B12 deficiency can occur for various other reasons too, such as not getting enough vitamin B12 from your diet. This is quite common for those who are on a strictly plant-based diet and do not take supplements," Svanfeldt says. 

Grace Walsh
Grace Walsh

A digital health journalist with over five years experience writing and editing for UK publications, Grace has covered the world of health and wellbeing extensively for Cosmopolitan, The i Paper and more.


She started her career writing about the complexities of sex and relationships, before combining personal hobbies with professional and writing about fitness. Everything from the best protein powder to sleep technology, the latest health trend to nutrition essentials, Grace has a huge spectrum of interests in the wellness sphere. Having reported on the coronavirus pandemic since the very first swab, she now also counts public health among them.