Vitamin B12 Deficiency: Symptoms, Causes & Treatment
Vitamin B12, or cobalamin, is a water-soluble vitamin essential for red blood cell formation, brain function, and DNA synthesis. Unlike some vitamins, your body doesn’t produce B12. You can only get it from animal-based foods or fortified products, making deficiency more common in vegans, vegetarians, and people with absorption issues.
Your body stores extra B12 in the liver, but a prolonged lack of intake or absorption can lead to a deficiency that causes serious health problems.
Benefits of Vitamin B12
Vitamin B12 supports various vital functions:
-
DNA and red blood cell production
-
Brain and nerve health
-
Healthy skin, nails, and hair
-
Energy and mood regulation
-
Bone strength and heart health
Common Symptoms of Vitamin B12 Deficiency
Vitamin B12 deficiency may take years to show, but common symptoms include:
-
Constant fatigue and weakness
-
Pale skin and bluish or brown-gray nails
-
Shortness of breath or heart palpitations
-
Glossitis (smooth, inflamed tongue)
-
Digestive issues and appetite loss
-
Tingling in hands or feet
-
Depression, memory loss, and irritability
-
Visual disturbances (optic neuropathy in rare cases)
Causes of Vitamin B12 Deficiency
You might be low on vitamin B12 due to:
-
A vegan or vegetarian diet lacking fortified foods
-
Pernicious anemia or autoimmune issues preventing B12 absorption
-
Gastrointestinal disorders like Crohn’s or celiac disease
-
Use of medications such as PPIs (omeprazole, lansoprazole), metformin, or chemotherapy drugs
-
Excessive alcohol consumption
How to Get Enough Vitamin B12
Natural Food Sources
Animal-based foods are the best sources:
-
Beef liver
-
Clams and oysters
-
Fish like tuna and salmon
-
Eggs and dairy products
-
Poultry and red meat
Fortified Foods for Vegetarians & Vegans
-
Breakfast cereals
-
Nutritional yeast
-
Fortified plant-based milks
-
Fortified breads and soy products
Vitamin B12 Dosage Guidelines
Daily recommended intake:
-
Adults (19+ years): 2.4 mcg
-
Pregnant: 2.6 mcg
-
Breastfeeding: 2.8 mcg
-
Children’s doses vary by age
B12 Supplements and Injections
When to Take Supplements
If you’re mildly deficient or can’t get enough from food, oral B12 supplements are effective. Options include:
-
B12-only tablets or capsules
-
Multivitamins or B-complex formulas
-
Sublingual (under-the-tongue) tablets
-
Nasal sprays
Tip: Even high doses (500–1000 mcg) are safe since your body expels excess in urine.
When You Need B12 Injections
Your doctor may recommend injections if you:
-
Have severe deficiency or anemia
-
Cannot absorb B12 through your gut (e.g., pernicious anemia)
-
Suffer from chronic gastrointestinal disorders
These injections may be short-term or lifelong, depending on the cause.
Risks of Untreated B12 Deficiency
Ignoring B12 deficiency can lead to:
-
Irreversible nerve damage
-
Difficulty walking or speaking
-
Depression and mood disorders
-
Permanent cognitive decline
How to Prevent B12 Deficiency
-
Include meat, eggs, or dairy in your diet
-
Add B12-fortified foods if you’re vegan or vegetarian
-
Take supplements if you’re at risk
-
Limit alcohol intake
-
Monitor medications that interfere with absorption
-
Test regularly if you have absorption disorders
Vitamin B12 and Pregnancy
Expecting mothers following a vegan diet must ensure adequate B12 intake. Deficiency during pregnancy can affect the baby’s brain and spinal development, leading to growth delays. Speak to your doctor about supplements or fortified foods if you plan to breastfeed exclusively.
Can You Take Too Much Vitamin B12?
While there’s no upper intake limit, extremely high doses (especially injections) may cause:
-
Acne or rosacea flare-ups
-
Heart palpitations
-
Rare adverse effects (though uncommon)
One study linked excess B12 to a higher mortality rate, but more research is needed.
