8+ important signs of vitamin B12 deficiency that are often overlooked

Of all the common vitamin deficiencies, vitamin B12 is among the most harmful. This crucial vitamin is responsible for such big tasks as making DNA and red blood cells, as well as helping your nervous system function properly. Despite its importance, however, your body doesn't make it naturally; we rely on food to supply enough vitamin B12 maintain good health.

If you suffer from Crohn's disease, celiac disease or an immune disorder such as Grave's disease or lupus, your doctor probably has talked to you about the dangers of vitamin B12 deficiency. People with those conditions are not the only ones who need to worry, however; vegans and vegetarians, as well as people over the age of 50, are at particular risk for this form of anemia. Here's how to know if you are vitamin B12 deficient.

1. Pale yellow skin. Red blood cells produce bilirubin as they break down, which causes jaundice.

2. Numbness and tingling. Vitamin B12 deficiency has a direct effect on the nerves. Numbness, tingling, tremors and problems with balance can point to depleted vitamin B12 levels.

3. Mood swings. The same deficiency that can cause tingling and numbness also can affect your mood. Anxiety, depression and extreme ups and downs can signal a lack of the vitamin B12 that helps synthesize important mood-regulating chemicals such as serotonin and dopamine. If you are feeling down, try these 7+ home remedies to boost your mood. And, of course, if the feeling lasts more than two weeks, seek the help of your family doctor or therapist.

4. Smooth, red tongue. Vitamin B12 can cause a loss of papillae on the tongue. Taste buds are located on the papillae, so if you lose a taste for food and no longer find eating enjoyable, talk to your doctor about checking your vitamin B12 level.

5. Eye problems. An extreme lack of vitamin B12 can damage the optic nerve. This can cause blurry or double vision, sensitivity to light and, in some cases, vision loss.

Related: 6+ ways to naturally improve eyesight and reduce eye strain

6. Burning feet. Nerve damage from vitamin B12 deficiency may manifest as a burning sensation in the feet. Like numbness and tingling, the sensation typically begins in the fingers or toes and, left untreated, can spread up the arms and legs.

7. Difficulty walking. If you stagger or lose your balance when walking, a vitamin B12 deficiency may be causing neurological damage, says Harvard Health Publications.

8. Memory loss. Difficulty thinking and memory loss are two more neurological symptoms of vitamin B12 deficiency.

If you are over the age of 50, a strict vegetarian or vegan, or have had weight loss surgery, talk with your doctor about having your B12 level checked. It's also a good idea if you take a proton-pump inhibitor such as Nexium, an H2 blocker such as Zantac, or metformin for diabetes.