What Are the Symptoms of Vitamin B12 Deficiency?

Vitamin B12 is a water-soluble, essential vitamin needed for many processes in the body. These processes are related to cognitive function, neurological function, digestive functions and energy needs.

When there is a vitamin B12 deficiency in the body, multiple systems are impacted. Early symptoms of this deficiency are often vague and subtle, whereas prolonged deficiency leads to more serious and acute symptoms.

Energy-related symptoms such as fatigue and weakness are common. So are cognitive symptoms such as brain fog or memory problems. Sometimes digestive symptoms, such as tongue swelling or mouth ulcers, can also persist. Late symptoms often present as neurological issues with muscle weakness, difficulty walking and balancing to tingling/ numbness in the hands and feet.

Clinical symptoms of B12 deficiency can be a sign for patients to seek medical help and get the appropriate tests. Following appropriate testing and relevant results, treatment is often started promptly to prevent long-term, deficiency related damage to the body.

For more information on the signs of B12 deficiency, please check out our dedicated webpage.

You can also browse our lifestyle medications (such as vitamin supplements) from our main Meds for Less page and choose the medicines that are right for you (Figure 1). We can easily, reliably and safely deliver the medicines of choice to your home address within 24 hours.

Figure 1: Symptoms of Vitamin B12 deficiency are often treated by Vitamin B12 supplementation.

Why Vitamin B12 Is Essential for the Body

Vitamin B12 is an essential water-soluble vitamin that the body cannot produce on its own, meaning you must get it from food or supplements. B12 plays a key role in the body’s functioning, including the formation of red blood cells, maintaining the health of the nervous system, DNA synthesis and cell division, as well as energy metabolism and functioning.

Common Symptoms of Vitamin B12 Deficiency

The symptoms of Vitamin B12 deficiency range from subtle symptoms (in early days) to more advanced symptoms (severe deficiency). Not everyone with a VB12 deficiency will develop these symptoms, and those who do notice that they develop gradually as opposed to suddenly.  The following are some of the Low B12 symptoms in adults.

Common and early symptoms of B12 defiency:

• Fatigue/ low energy
• Lightheadedness
• Weakness
• Shortness of breath (due to anaemia caused bya  lack of red blood cell development)
• Heart palpitations
• Pale or yellowish skin

Neurological symptoms:

• Tingling or “pins and needles” feeling in the hands and feet (parasthesia)
• Numbness in the extremities
• Poor balance or coordination
• Memory problems and forgetfulness
• Mood changes (irritability, low mood or depression)
• Vision problems

Gastrointestinal/digestive symptoms:

• Loss of appetite
• Weight Loss
• Bloating, diarrhoea, or constipation
• Mouth ulcers
• Glossitis (a painful, smooth or painful tongue)

More serious symptoms (when the deficiency gets more severe):

• Peripheral neuropathy (never damage in the body peripheries)
• Permanent nerve damage
• Gait disturbances (balance issues)
• Cognitive decline resembling dementia

Neurological Signs of Low Vitamin B12 Levels

Vitamin B12 is responsible for the development of a layer around nerves called Myelin. A deficiency of myelin leads to nerve damage, which in turn can cause the neurological symptoms associated with B12 deficiency. These symptoms include:

• Tingling in the hands and feet due to nerve damage in the peripheries (parasthesia)
• Numbness in the extremities (hands/feet)
  • This often progresses symmetrically
• Difficulty walking or balance problems
  • Poor coordination
  • Feeling unsteady and needing excessive support when walking
• Muscle weakness due to nerve damage
• Cognitive impairment leading to brain fog
  • Signs like forgetfulness or poor concentration
  • Reduced mental clarity and slow thinking

Long term and Severe B12 deficiency symptoms can lead to permanent nerve and balance issues.

Cognitive and Mental Health Symptoms of Vitamin B12 Deficiency

Some clinical problems that manifest as cognitive and mental health symptoms of vitamin B12 deficiency include:

• Memory problems such as:
  • Reduced ability to recall information
  • Forgetting recent tasks or conversations
  • May resemble early dementia in prolonged deficiency
• Difficulty concentrating (brain fog), such as:
  • Trouble focusing or information processing
  • Feeling mentally slower or less sharp
  • Reduced mental stamina or attention
• Slowed thinking or Reduced executive function,n such as
  • Difficulty making decisions
  • Mental processing feels slower or effortful
• Mood changes such as:
  • Depression and persistent low mood
  • Reduced motivation or interest
  • Mood swings and irritability
• Personality or behavioural changes (in severe, prolonged deficiency):
  • Loss of interest in hobbies/ relationships
  • Social withdrawal
• Sleep disturbances:
  • Vivid dreams or nightmares
  • Insomnia or fragmented sleep

Physical and Fatigue-Related Symptoms Linked to B12 Deficiency

The following are some of the physical symptoms and fatigue-related symptoms linked to vitamin B12 deficiency. This is due to inadequate Vitamin B12 levels, causing fewer healthy red blood cells to circulate in the bloodstream:

• Persistent low energy and B12 deficiency fatigue
  • Feeling tired even after adequate sleep
  • Reduced stamina when doing routine tasks
• Weakness
  • Struggling to lift usual weights
  • Arms or Legs feel heavy or drained
• B12 defiency anemia symptoms
  • Shortness of breath on exertion
  • Breathlessness when climbing stairs or walking briskly
• Palpitations or Heart racing
  • The heart beats faster to respond to low red blood cells in an attempt to compensate

Skin, Hair, and Nail Changes Associated With Low Vitamin B12

Vitamin B12 is required for cell growth, DNA synthesis and protein production. Hence, it is required for maintaining healthy tissues and rapid cell turnover. A lack of vitamin B12 causes skin, nail and hair changes. These changes include:

• Dry, Flaky skin
• Hair thinning or increased shedding
• Brittle nails that break easily

The anaemia (megaloblastic anaemia) that arises due to a lack of vitamin B12 can also cause the following symptoms in the skin:

• Pale or sallow skin
• Slower hair growth
• Weak or slow-growing nails

Some people with vitamin B12 deficiency also notice hyperpigmentation (dark spots) on their hands and feet, knuckles and skin folds.

Digestive and Appetite-Related Symptoms of Vitamin B12 Deficiency

The following are digestive and appetite-related symptoms of Vitamin B12 deficiency and an overview of how they may develop:

• Loss of appetite
  • Reduced desire to eat or early fullness can contribute to unintentional weight loss

This may be due to altered nerve signalling and taste changes

• Weight loss
  • Due to reduced appetite, malabsorption and nausea
• Nausea
  • Can occur due to reduced nerve damage, which reduces gastric motility and delays stomach emptying.
• Diarrohea
  • Loose stools or increased stool frequency

This can be due to impaired DNA synthesis of cells lining the gut wall. These cells normally help with food absorption, and their lack of proper development can cause reduced food absorption and increased stool frequency.

• Glossitis and mouth ulcers
  • Smooth, inflamed tongue – sometimes with a burning sensation

This can be due to a lack of appropriate cell turnover of the cells lining the tongue or mouth

Risk Factors: Who Is More Likely to Develop Vitamin B12 Deficiency?

The following are some groups which are more at risk of developing a vitamin B12 deficiency. Risks of deficiency can occur due to groupings such as low intake, poor absorption, or increased need.

• Vegetarian or Vegan diets:
  • Vitamin B12 deficiency is naturally found almost only in animal foods (meats and eggs). Without meat in diets or a fortified vegetarian diet, deficiency can be common.
• Older Adults (typically those above 50 years of age):
  • Reduced stomach acid (due to atrophic gastritis) can impair the release of vitamin B12 from food
  • Atrophic gastritis can lower the production of intrinsic factor (a human protein), which makes absorption of B12 less efficient.
• Individuals with absorption issues:
  • People with issues such as:
    • Pernicious anaemia,
    • Crohn’s disease,
    • Coleiac disease
    • Surgical removal of the stomach or the Illeum (end of the small intestine)
  • These issues can impair the absorption of vitamin B12 in different ways and increase the risk of developing a vitB12 deficiency.
• People with chronic alcohol use:
  • Alcohol-related gastritis can reduce the absorption of vitamin B12 from diets
  • Liver-related issues due to alcohol can also affect Vitamin B12 storage and efficient use by the body.

 How to Diagnose Vitamin B12 Deficiency

If you are looking to understand answers to questions such as How to know if you have B12 deficiency, then this article is for you.

Vitamin B12 deficiency is diagnosed based on a combination of clinical tests and blood markers, and some tests to see how well VitB-12-dependent pathways are working. Because B12 levels can appear “normal” even when a deficiency occurs, this combination of tests often gives the most accurate clinical picture.

The following is an overview of how a combination of elements can be used to diagnose Vitamin B12 deficiencies:

• Firstly, a clinician will look at a patient’s symptoms and risk factors for vitamin B12 deficiency and determine if there is indeed a risk of VitB12 deficiency. If this is the case, the patient will be advised to undergo blood tests.

• Blood tests – A range of blood tests will be done on an initial basis to determine if the levels of VitB12 in the body are less than normal. These are initial screening tests that usually just look at whether Vit B12 (also known as Cobalamin) levels in the blood are in the reference range of “normal”.

• If the initial screening tests indicates anemia – A full blood count (FBC) looks for patterns in the blood indicating anaemia. They look at parameters such as haemoglobin levels, red blood cell volume levels or the number of immature red blood cells floating in the bloodstream.

In this full blood count, a high MCV (Mean Cell Volume), indicating large and malformed red blood cells, can be a sign of anaemia.

• If such signs of anaemia exist, then a “blood smear” is ordered, where a droplet of blood is smeared across a plate and examined under a microscope. If certain cell types, such as “Macro-ovalocyte” or “Hyper-segmented neutrophils” appear, then this supports a diagnosis of Vit-B12 deficiency. Please speak to your healthcare provider to find out more about what these abnormal cell types are and what they mean.

• If such clinical symptoms and blood tests are supportive of VitB12 deficiency, sometimes a folate (B9) panel is also run, as these deficiencies are commonly seen together.

• Functional tests such as the methylmalonic acid (MMA) or homocysteine may be used to detect or diagnose a VitB12 deficiency. In cases where the vitamin B12 levels in the blood tests look normal. These functional tests can help look at metabolic pathways that are determined by good VitB12 levels and determine if there is actually an impact of VitB12 deficiency.

 When to Seek Medical Help

You should seek medical help for a vitamin B12 deficiency if symptoms are worsening, persistent or affecting daily life. You should also seek help if you have risk factors of VitB12 deficiency, as well as early signs and symptoms of deficiency.

It is important to get assessed for VitB12 deficiency early if you have signs and symptoms, as long-term deficiencies can cause nerve damage.

The following is an overview of some situations in relation to VitB12 deficiency where you should seek medical help immediately, or seek advice soon (but not immediately) or seek testing if you have relevant risk factors:

Situations in which to seek immediate medical help:

• If you notice tingling, numbness or “pins and needles” in your hands and feet
• Balance problems, such as frequent tripping and difficulty walking.
• Progressive muscle weakness
• Vision changes
• Rapid heart rate or shortness of breath at rest
• Confusion, memory issues or noticeable mood changes

Situations in which to seek medical advice soon (not emergency, but do not delay):

• Persistent fatigue or low energy
• Pale or yellowish skin
• Glossitis (smooth and painful tongue) or recurrent ulcers
• Loss of appetite or unexplained weight loss
• Digestive issues (nausea, constipation or diarrhoea) lasting 2-3 weeks

Risk factors which can require you to undergo testing:

• Having a strict vegan or vegetarian diet without B12 supplementation
• Being over 50
• Taking metformin or Proton Pump Inhibitors (Pantoprazole or Omeprazole) long-term
• Having a family history of prenicious anaemia

If you have any concerns regarding any symptoms that you may feel are a sign of Vitamin B12 deficiency, please seek the advice of your healthcare provider.

Conclusion

Vitamin B12 plays a crucial role in the body for energy production, blood formation, nerve function, and brain health. Because it plays a role in DNA synthesis, protein production, and maintaining the nervous system, a deficiency in vitamin B12 can affect multiple body systems simultaneously and cause fatigue, digestive issues, neurological problems, and cognitive symptoms.

Symptoms of Vitamin B12 can be subtle at first, such as tiredness, pallor, weakness or skin changes. However, it is important to recognise distinguishing features such as loss of sensation in the hands and feet, tingling in the extremities, relevant digestive symptoms and others. This is to allow early detection and treatment of vitamin B12 deficiency before prolonged deprivation can cause permanent damage (mostly to the nervous system).

Please speak to your healthcare provider if you are worried about Vitamin B12 deficiency to see which tests, diagnostic methods and treatments would be right for you.