Vitamin B12 deficiency symptoms: Metallic taste in your mouth can mean you're lacking B12 Express.co.uk Vitamin B12 is essential for healthy oral tissues. Its deficiency can affect the mouth early.., Oral effects , red,smooth,painful tongue(glossitis), recurrent mouth ulcers , burning mouth Altered Taste ChemoExperts Vitamin B12 deficiency symptoms: Add B12 foods to diet with metal taste Express.co.uk 5 Reasons You Get a Metallic Taste in Your Mouth (And How to Avoid It)