B12 is a vitamin responsible for producing healthy red blood cells in your body. It also facilitates DNA synthesis and is needed for normal nerve function, notes the Merck Manuals Online Medical Library. According to MedlinePlus, the healthy range of vitamin B12 in your blood is from 200 to 900 pg/mL. B12 levels below 200 pg/mL are considered low and can cause certain symptoms.
Anemia
Vitamin B12 deficiency can cause anemia, Merck Manuals notes. Anemia induced by low B12 levels can cause dizziness and elevated heart rate, if severe. Your skin may also appear pale due to insufficient red blood cells. As the anemia worsens, you may become fatigued. The anemia disappears once vitamin B12
Gastrointestinal Problems
Low vitamin B12 levels can cause you to experience nausea and appetite loss, Drugs.com notes. Furthermore, you may notice increased flatulence and severe diarrhea. These symptoms occur gradually; they increase in severity if B12 levels continue to fall.
Muscle Weakness
Persistently low vitamin B12 levels may cause muscle weakness, Merck Manuals notes. Motor skills such as walking may be impaired. This symptom progresses slowly; it may become irreversible if vitamin B12 levels remain low.
Neurological and Optical Problems
Vitamin B12 deficiency can cause neuropathy -- damage to your nerves. Neuropathy may manifest as a tingling sensation in your hands and feet. You may also find it more difficult to determine the position of your arms and legs, notes Merck Manuals. This symptom usually develops in those aged 60 and above. In addition, low vitamin B12 levels can affect your optic nerves, causing vision loss, according to the CDC.
Cognitive Changes
Vitamin B12 deficiency can affect your cognitive functions, causing confusion, hallucinations, changes in personality and even dementia, the Centers for Disease Control and Prevention explains. Violent tendencies may emerge as a result of severe vitamin B12 deficiency.
Shortness of Breath and Arrhythmia
Deficient levels of vitamin B12 can cause shortness of breath, according to the CDC. You may also experience arrhythmia due to low vitamin B12 levels. The combination of shortness of breath and arrhythmia can lead to fatigue. These symptoms may manifest gradually, making diagnosis more difficult.
