If you have trouble with nutrient absorption due to the presence of intestinal inflammation, poor gut health, or a deficiency of those intrinsic factors we mentioned, then taking an oral supplement may not be that helpful
Dizziness and fatigue Memory loss, difficulty in concentrating, and cognitive difficulties Anemia or iron deficiency anemia Muscle cramps Shortness of breath Erratic moods and possible signs of mental health disorders such as depression Irregular or halted menstruation Inflamed tongue Low energy Hair Your Vitamin B12 deficiency may also be a symptom in itself of other diseases such as SIBO ( Small Intestinal Bacterial Overgrowth ) or other gut-related disorders
These stem from impaired red blood cell production and nerve function, affecting oxygen transport and mental clarity.
Eventually, the risk of major diseases including cancer, heart stroke, and dementia
Biochemistry Research International
The NIH professional fact sheet is a reliable reference