Vitamin B12 is necessary for ensuring that red blood cells, brain function, and nerve tissue remain healthy and productive. The human body can store several-years-worth of B12, although people following a vegetarian or vegan diet or those with absorption issues are at risk of deficiency. A vitamin B12 deficiency or cobalamin deficiency is relatively common -- there are more than 3 million cases of vitamin B12 deficiency in the United States alone.

Loss of Muscle Strength

When doctors cannot trace muscle fatigue to a specific issue such as an over-the-top workout or a recent illness, they may look into a vitamin B12 deficiency. Too little of this vital nutrient can restrict the amount of oxygen reaching the red blood cells, which affects muscle strength to varying degrees.



One of the first signs of a vitamin B12 deficiency is frequent mental and physical fatigue regardless of how much sleep the person is getting. If an individual consistently gets a full eight hours of sleep every night and is still falling asleep during lunchtime, then a lack of vitamin B12 could be to blame. Much like muscle fatigue, too little oxygen in the red blood cells can lead to chronic lethargy.



Everyone tends to be a little forgetful at times. However, when this becomes the norm, it may be time to see a doctor for blood tests, which could reveal a B12 deficiency. Yet again, it is lack of oxygen in the blood -- this time the blood being delivered to the brain -- that causes this symptom.


Pins and Needles

Another early warning sign of a vitamin B12 deficiency is a feeling of electrical charges through the body. Many individuals describe a pins and needles sensations similar to the prickly feeling that comes from sitting on one foot or laying on one arm for too long. Like most symptoms of vitamin B12 deficiency, this is a result of too little oxygen in the red blood cells.


Pale Skin

Ashen skin on a person who has been receiving sufficient sunlight can indicate a vitamin B12 deficiency. Lack of oxygen in the blood prevents the rosy glow generally associated with good health. Individuals may also experience yellow or jaundiced skin coloring; this occurs if red blood cells become fragile, breaking apart quite easily. This breakdown releases bilirubin, the cause of jaundice.



Feeling dizzy for no reason can be an early warning sign of a vitamin B12 deficiency. Most people notice this symptom especially when they stand or sit too quickly, or when walking up a flight of stairs, and it usually comes on and passes quickly. Dizziness is often attributed to other factors, especially in the elderly, and B12 deficiencies are often overlooked.



Vitamin B12 is crucial for overall mental health. Some people with insufficient B12 experience anxiety and depression, with varying intensity. When such symptoms, which many people feel from time to time, do not ebb when the issue in question passes or is resolved, the feelings could indicate a vitamin deficiency or any number of other health concerns.


Changes in the Tongue

All healthy people have little bumps across the surface of their tongues called papillae. Some patients experiencing vitamin B12 deficiency may notice these bumps appear to vanish when the tongue becomes inflamed, a condition called glossitis. Some may also experience soreness along the back side of the tongue or a burning sensation.


Vision Changes

Sometimes patients with a vitamin B12 deficiency may also experience vision problems including fuzzy spots, blurry vision, peripheral shadows, and double vision. While these issues are symptomatic of many conditions, they can also result from insufficient vitamin B12. Although rare, optic neuropathy is a serious complication of a B12 deficiency where the optic nerve becomes brittle and damaged, sometimes resulting in central vision loss.


Weight Loss

Weight loss can result from vitamin B12 deficiencies. The changes to the tongue that cause the papillae to "disappear" directly affects the taste buds, which are contained within. As a result, an individual may eat less and subsequently lose weight.


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