Can B-complex vitamins be taken long-term?

　　B vitamins can generally be taken in appropriate amounts for a long time, but should not be consumed in large quantities for extended periods.

　　If an individual has specific risks of malnutrition—for example, vegetarians may lack vitamin B12, or elderly people may have potential deficiencies in B vitamins due to decreased absorption capacity—then long-term supplementation with B vitamins under a doctor's guidance is safe and beneficial. In some cases, such as pregnant women needing additional folic acid to prevent neural tube defects, or patients with chronic diseases who may require long-term B vitamin supplementation to maintain nerve health, supplementation may be necessary.

　　Although B vitamins are beneficial to health, long-term excessive intake may cause various side effects; therefore, excessive consumption over extended periods should be avoided. Overdose may lead to gastrointestinal symptoms such as nausea, vomiting, abdominal pain, and diarrhea. Long-term excessive intake may increase the burden on the liver and kidneys, affecting their normal function.

　　For healthy individuals, obtaining sufficient B vitamins through a balanced diet is a safer and healthier approach. It is recommended to eat more whole grains, fresh vegetables, fruits, legumes, and other foods to ensure balanced nutrition and meet daily requirements.