Vitamin B12 is a crucial nutrient that supports the body's normal functions, especially for the nervous system and blood cells. It is particularly important for people who eat few or no animal products, as these are the main natural sources of the vitamin. According to the German Society for Nutrition (DGE) and the National Agency for Food, Environmental and Occupational Health Safety (Anses), adults should aim to consume about 4 micrograms (μg) of vitamin B12 daily. This amount increases slightly during pregnancy (4.5 μg) and breastfeeding (5.5 μg), as the body's needs change during these times. Vitamin B12 is primarily found in animal-based foods, making it a key concern for vegetarians and vegans. Animal sources like offal—organ meats—are especially rich in B12. For example, 100 grams of beef liver contains 46.9 μg of vitamin B12, and 100 grams of veal kidney also provides a substantial amount. These foods are not commonly consumed in large quantities by many people, but they are important for those who do eat them. For vegetarians, eggs, cheese, and dairy products can provide adequate amounts of vitamin B12. However, vegans, who avoid all animal products, must rely on fortified foods and supplements to meet their needs. Plant-based sources like spirulina, a type of blue-green algae, are often marketed as containing B12, but they are not considered reliable or sufficient sources for human nutrition. This means that vegans need to be particularly mindful of their intake through fortified products such as plant-based milk, breakfast cereals, or B12 supplements. Maintaining adequate levels of vitamin B12 is important for overall health, and for those following a plant-based diet, careful planning and supplementation are often necessary. Healthcare professionals recommend regular blood tests to monitor B12 levels and ensure that dietary intake is sufficient. This is especially important for pregnant and breastfeeding individuals, as well as those with dietary restrictions or medical conditions that affect nutrient absorption.