You're standing in your kitchen, but you can't remember why you're there. Should you blame your forgetfulness on stress? Aging? Another possibility: Memory loss can indicate a vitamin B12 deficiency. Without this vital nutrient, your body cannot maintain a healthy nervous system or form red blood cells, potentially resulting in poor memory, confusion, numbness or tingling in your hands and feet, fatigue, and anemia. What's more, prolonged deficiency can contribute to dementia and even Alzheimer's disease, making B12 even more important as you age. The Institute of Medicine recommends that people over age 50 take supplements or eat fortified food to meet the recommended dietary allowance of 2.4 mcg for adults. Start by eating foods rich in B12, such as red meat, liver, clams, wild salmon, eggs, yogurt, and fortified breakfast cereal. To be on the safe side, take a daily supplement with 10-100 mcg; look for easy-to-absorb tablets that dissolve under your tongue.