Vitamin B12 is found naturally only in animal foods. Some of the best sources of Vitamin B12 include clams, liver, fortified cereal, trout, salmon, canned tuna fish, beef, nonfat plain Greek yogurt, low-fat milk, ham and eggs. Cheese is also a rich source of vitamin B12.<br />Vitamin B12 deficiency occurs due to decreased intake of the vitamin, increased requirements or poor absorption. Some common causes of Vitamin B12 deficiency include pernicious anemia, which is an autoimmune condition that affects your stomach, a strict vegan diet, certain medi-cations which block absorption of vitamins, and certain stomach or intestinal conditions or surgeries that prevent absorption of enough vitamin B12.<br />Some common symptoms of Vitamin B12 deficiency include fatigue, shortness of breath, dizziness, pale or yellowish skin, irregular heartbeats, weight loss, numbness or tingling in the hands and feet, muscle weakness, personality changes, unsteady movements, mental confusion or forgetfulness. Severe, long-term deficiency may lead to loss of mobility, problems walking or memory loss.<br />Symptom Description<br />Fatigue Feeling tired or weak<br />Shortness of breath Difficulty breathing or catching your breath<br />Dizziness Feeling lightheaded or faint<br />Pale or yellowish skin Change in skin color<br />Irregular heartbeats Heart palpitations or changes in heart rhythm<br />Weight loss Losing weight without trying<br />Numbness or tingling Sensations in the hands and feet<br />Muscle weakness Difficulty with physical tasks<br />Personality changes Changes in mood or behavior<br />