While everyone should have proper diet and nutrition there are sections of the population that have a greater need to monitor their B12 levels
Mood Changes Changes in mood including feelings of sadness or irritability can sometimes be linked to low vitamin B12 levels
Reviewed by the PeptideMind Team Updated July 15, 2026 AHK-Cu Dosage Guide, Benefits & Side Effects AHK-Cu is a copper tripeptide studied for hair follicle growth, collagen production, and skin firmness
Common signs include: Ongoing fatigue or weakness Pale skin Numbness or tingling in the hands and feet Brain fog, forgetfulness, or trouble concentrating Low mood, anxiety, or irritability Poor appetite or digestive upset When B12 is low, your metabolism slows, you have less energy for activity, and appetite signals can get thrown off, all of which make weight loss harder
Abnormal response of melanin-concentrating hormone deficient mice to fasting hyperactivity and rapid eye movement sleep suppression
If you take B12 tablets or sublingual supplements, you might feel small changes in a week or two