Vitamin B12 Deficiency: Symptoms, Causes, and Treatment Options

Vitamin B12, also known as cobalamin, is a water-soluble vitamin essential for several critical bodily functions. It plays a key role in producing red blood cells, synthesizing DNA, and maintaining the health of the nervous system. A deficiency in this nutrient can lead to a cascade of health issues, some of which may become irreversible if not addressed promptly. According to the National Institutes of Health (NIH), the recommended daily intake for adults is 2.4 micrograms, yet millions worldwide fall short, often unknowingly.

Symptoms of B12 deficiency can be subtle at first, making it easy to overlook. Early signs include persistent fatigue, weakness, and pale or jaundiced skin due to anemia. As the deficiency progresses, neurological symptoms emerge, such as numbness or tingling in the hands and feet, difficulty walking, and even memory loss or mood changes like depression. In severe cases, it can mimic dementia, particularly in older adults. The World Health Organization estimates that up to 15% of people over 60 may be deficient, partly due to reduced stomach acid production, which impairs B12 absorption from food.

The causes of B12 deficiency are diverse. Dietary insufficiency is a primary culprit, especially for vegans and vegetarians, as B12 is naturally found almost exclusively in animal products like meat, fish, eggs, and dairy. For example, a 3-ounce serving of cooked beef liver provides over 70 micrograms—far exceeding daily needs—while plant-based foods offer none unless fortified. Absorption issues are another major factor. Conditions like pernicious anemia, an autoimmune disorder that destroys stomach cells needed to absorb B12, affect about 1-2% of older adults. Other risks include Crohn’s disease, celiac disease, or surgeries like gastric bypass, which disrupt the gut’s ability to process the vitamin. Certain medications, such as proton pump inhibitors or metformin, can also interfere over time.

Treatment depends on the severity and cause. For mild cases, increasing intake of B12-rich foods—think clams (84 micrograms per 3 ounces), salmon, or fortified cereals—may suffice. Supplements are widely available, with oral doses ranging from 500 to 1,000 micrograms daily often recommended to rebuild stores. In cases of poor absorption, intramuscular injections (typically 1,000 micrograms monthly) bypass the digestive system entirely, offering rapid relief. Doctors may also run blood tests to check B12 levels (normal range: 200-900 pg/mL) and homocysteine, which rises when B12 is low, signaling potential cardiovascular risks.

Left untreated, the consequences can be dire. Prolonged deficiency damages the myelin sheath around nerves, leading to permanent neuropathy. Early intervention is key, and awareness is growing—public health campaigns increasingly target at-risk groups like vegans and the elderly. If you suspect a deficiency, consult a healthcare provider for a tailored plan.