Changes to the Tongue
When a person is healthy, they will have small bumps that go across their tongue. These bumps are called papillae. When the papillae become inflamed because of a vitamin B-12 deficiency in the body, a condition called glossitis can occur. This causes the bumps on the tongue to vanish. Other symptoms may include a burning sensation or soreness along the sides of the tongue.
Vision Problems
Another warning sign that you may be dealing with a vitamin B12 deficiency is vision changes. You may notice blurry vision, double vision, fuzzy spots, or peripheral shadows. It is likely that your doctor will first rule out other possible illnesses before ordering a blood test to check your vitamin B12 levels. However, it may be to blame. With severe vitamin B-12 deficiency, the optic nerve can become damaged and brittle, which results in the loss of central vision.