Vitamin B12 is essential for red blood cell formation, neurological function, and DNA synthesis. As the article states, “A deficiency can lead to serious health issues,” so understanding its signs and sources is key.

**Symptoms** include fatigue, weakness, and megaloblastic anemia. “Neurological issues” such as numbness, tingling in hands and feet, balance problems, and nerve damage may also occur. Severe deficiency can cause “breathlessness and heart palpitations,” along with cognitive issues like memory loss and brain fog.

**Causes** often stem from “dietary deficiency,” especially in vegans and vegetarians, since B12 is mostly found in animal products. Malabsorption from conditions like Crohn’s disease, celiac disease, and pernicious anemia can also interfere with absorption. Aging is another factor, as “older adults may have reduced stomach acid levels.”

**Sources** of vitamin B12 include “organ meats” like liver, “shellfish” such as clams and oysters, and fish like salmon and trout. Beef, dairy products, eggs, and fortified foods (plant-based milks, cereals) are also good options.

**Conclusion**: Maintaining adequate B12 levels is vital. “Those at risk… should monitor their B12 levels” and aim for a balanced diet to prevent deficiency and support long-term health.