維他命B12是水溶性維他命的一種。我們體內多項重要的代謝作用都需運用到維他命B12，例如： ．製造紅血球 ．維持神經線正常運作 ．製造DNA ．製造荷爾蒙 ．代謝脂肪及蛋白質
Vitamin B12 is a water-soluble vitamin that plays important roles in different human metabolic processes. Vitamin B12 is required in the following processes: ．Red blood cell formation ．Neurological function ．DNA synthesis ．Hormone synthesis ．Fat and protein metabolism 每名健康的成年人每日需要攝取2.4微克的維他命B12。動物性食物，如魚、紅肉、家禽、蛋類、奶類等都是
維他命B12的主要來源，而植物性食物大多天然不含維他命B12。部份早餐穀物會添加了維他命B12，供素食者多一個選擇。 Healthy adults’ Recommended Daily Allowances (RDAs) for Vitamin B12 are 2.4mcg for both men and women. Vitamin B12can naturally be found in animal products, but not in plant foods. Some breakfast cereals are fortified with Vitamin B12, which make them good sources of
Vitamin B12 for strict vegetarians and vegans.
| 食物 |
每食用份量含量 (微克) |
| 三文魚, 煮熟, 3安士 |
4.8 |
| 吞拿魚, 罐裝水浸, 3安士 |
2.5 |
| 早餐穀物, 添加維他命B12, 每食用份量 |
1.5 |
| 牛肉, 西冷, 烤熟, 3安士 |
1.4 |
| 牛奶, 低脂, 1杯 |
1.2 |
| 蛋, 烚熟, 1 隻 |
0.6 |
| 雞胸肉, 烤熟, 3安士 |
0.3 |
| Food |
mcg per serving |
| Salmon, sockeye, cooked, 3 ounces |
4.8 |
| Tuna fish, light, canned in water, 3 ounces |
2.5 |
| Breakfast cereals, fortified, 1 serving |
1.5 |
| Beef, top sirloin, broiled, 3 ounces |
1.4 |
| Milk, low-fat, 1 cup |
1.2 |
| Egg, whole, hard boiled, 1 large |
0.6 |
| Chicken, breast meat, roasted, 3 ounces |
0.3 |
天然食物中的
維他命B12與蛋白質結合在一起，不能直接被吸收。胃液中的胃酸和蛋白酶需要把維他命B12從蛋白質中分隔出來，再結合gastric intrinsic factor (GIF) ，才能讓維他命B12被人體吸收及運用。若腸胃結構因人為或天然因素受損，維他命B12的吸收能力便會因此下降。一些有較高風險患上維他命B12缺乏症的族群包括： ．長者 ．惡性貧血 (pernicious anemia) 患者 ．腸病患者，如乳糜瀉 (celiac disease)、克隆氏症 (Crohn’s disease) ．曾進行胃部手術人士，如繞胃、胃部切除、迴腸切除手術 ．素食者 我們應盡可能透過日常不同的飲食配撘以滿足每日各項的營養所需。若因任何原因不能進食魚、紅肉、家禽、蛋類、牛奶及其制品等，或您是以上其中一個高風險族群，請諮詢您的註冊營養師及醫生，以確保您飲食中的
維他命B12是足夠。 In nature,
Vitamin B12 bounds to protein in food. Hydrochloric acid and gastric protease in our stomach are required to set Vitamin B12 free, and then free Vitamin B12 needs to combine with gastric intrinsic factor (GIF), which is also produced by our stomach, in order to be absorbed. When the structures of stomach or ileum are altered intentionally by surgeries or unintentionally by aging or by diseases, the efficiency of processing and absorbing Vitamin B12 will then be impacted. Some populations are at higher risk of Vitamin B12 deficiency than others: ．Older adults ．Individuals with pernicious anemia ．Individuals with gastrointestinal disorders, such as celiac disease and Crohn’s disease ．Individuals who have had gastrointestinal surgery, such as surgery to remove/ bypass all or part of the stomach, surgery to remove distal ileum ．Strict vegetarians and vegans It is recommended that nutritional needs should be met primarily from foods. If you avoid fish, red meat, poultry, eggs and milk in your diet or simply dislike them all, or you fall into one of the at risk populations above, talk to your registered dietitian and health care provider to find out if you are consuming adequate
Vitamin B12 in a regular basis. 資料來源：National Institutes of Health Office of Dietary Supplements, Materials are adapted from National Institutes of Health Office of Dietary Supplements,
https://ods.od.nih.gov/factsheets/VitaminB12-HealthProfessional/
