5 Signs of a Vitamin B12 Deficiency

Vitamin B12 plays a central role in producing red blood cells, maintaining the nervous system, supporting DNA synthesis, and converting the food you eat into usable energy. Without enough of it, those processes start to break down. Most people get B12 through animal products like meat, fish, eggs, and dairy, which are the primary dietary sources. This is partly why the deficiency is more common than people expect, particularly in those who eat little or no animal products.

But diet isn’t the only factor. B12 absorption depends on a healthy digestive system, and a number of common conditions and medications interfere with that process, regardless of how much B12 someone is getting. Age also plays a role, since the stomach produces less of the acid needed to absorb B12 as people get older. As a result, many people with low B12 levels don't realize their ongoing fatigue or memory issues may be linked to a deficiency.

If you have critically low levels, a B12 injection is often the most effective way to correct the issue quickly, bypassing the digestive absorption problems that may have caused the problem in the first place. But figuring out whether you need one, how low your levels really are, and what dose and frequency make sense requires proper testing and a specialist who can administer the right treatment. 

At Advanced Allergy, Asthma, & Immunology Center PA in San Antonio and Schertz, Texas, our team, led by board-certified allergist Patricia Gomez Dinger, DO, offers exactly that kind of care, testing your B12 levels accurately and providing treatment tailored to what your body needs. Here, we cover five signs of a B12 deficiency and what to do if they sound familiar.

1. Persistent fatigue and weakness

Fatigue is one of the most common and earliest signs of B12 deficiency. B12 is essential for producing red blood cells, which carry oxygen throughout the body. When levels are low, your body produces fewer healthy red blood cells, which means less oxygen reaches the tissues and muscles that need it. The result is a deep, persistent fatigue along with general weakness that makes everyday tasks feel more draining than they should.

1. Numbness or tingling in the hands and feet

B12 plays a critical role in maintaining the protective coating around nerves, called the myelin sheath, which allows nerve signals to travel properly throughout the body. When B12 levels drop too low for too long, that protective coating can become damaged, and nerve signals start to misfire. The result is a sensation of numbness, tingling, or pins and needles, most commonly in the hands and feet.

1. Pale or yellowish skin

Low B12 leads to a type of anemia in which red blood cells are abnormally large and fragile, breaking down faster than the body can replace them. As those cells deteriorate, they release a compound called bilirubin, which can give your skin and the whites of your eyes a subtle yellowish tinge, similar to jaundice. 

More commonly, people with B12 deficiency simply appear pale, since fewer healthy red blood cells circulating through the body means less of the color that gives skin its normal tone. 

1. Difficulty concentrating and memory problems

Difficulty concentrating, slower thinking, trouble recalling information, and a general sense of mental fog are all associated with low B12 levels. This is a particularly important sign to take seriously in older adults, since cognitive symptoms of B12 deficiency are sometimes mistaken for early signs of dementia. 

Correcting the deficiency can significantly improve cognitive symptoms when they’re caught and treated in time.

1. Mood changes

B12 plays a role in the production of neurotransmitters that regulate mood, and a deficiency has been linked to symptoms of depression, irritability, and increased anxiety. People dealing with a B12 deficiency sometimes notice a shift in their mood or emotional resilience. It can be easy to attribute these changes to stress rather than considering a nutritional cause.

While B12 deficiency isn’t the only possible explanation for mood changes, it’s worth ruling out, particularly when it shows up alongside other symptoms on this list like fatigue or difficulty concentrating.

A B12 deficiency can affect your energy, your nervous system, your skin, your cognition, and your mood. Because the symptoms overlap with so many other common explanations, it often goes unrecognized for far longer than it should.

Book an appointment with us today to find out if low B12 is behind any troubling symptoms you’ve been experiencing.