Vitamins are essential nutrients your body needs in small amounts to perform an array of important functions. Eating a variety of foods helps to make sure you meet your nutrient needs. Vitamin B12 is an example of an essential nutrient that is primarily found in animal products. Knowing your daily requirement for vitamin B12 can help you determine how to vary your food choices to meet your needs.
Daily Requirements
Your daily vitamin B12 needs vary depending on your age. Infants ages 0 to 12 months need 0.4 to 0.5 mcg of vitamin B12 a day. Children ages 1 to 3 need 0.9 mcg a day, those 4 to 8 need 1.2 mcg and 9 to 13 need 1.8 mcg of vitamin B-12 a day. Teens and adults over the age of 14 need 2.4 mcg of vitamin B12 to meet daily needs. During pregnancy a woman's vitamin B12 needs increase to 2.6 mcg, and while breastfeeding to 2.8 mcg per day.
Function
Vitamin B-12 has a number of important roles in your body. It is necessary for the proper formation of red blood cells, assists with neurological function and is needed to make DNA.
Absorption
Vitamin B-12 requires a specific environment for absorption into your body. Vitamin B-12 is bound to protein in food, and the acid and enzymes in your stomach help release the vitamin B-12 from these proteins. But in order for vitamin B-12 to be absorbed into your bloodstream, it must than combine with a protein in the stomach called intrinsic factor. Changes in the acidity of your stomach and your ability to make or release intrinsic factor can effect your ability to absorb vitamin B-12.
Deficiencies
Although most children and adults in the United States adequately meet their vitamin B-12 needs, deficiencies can occur. Older adults, people with pernicious anemia -- an autoimmune disorder that affects the ability to make intrinsic factor -- and those with low stomach acid are at risk of developing a deficiency. A vitamin B-12 deficiency leads to megaloblastic anemia, fatigue, weakness, loss of appetite and weight loss. It can also cause neurological damage, such as numbness in the hands and feet, confusion, poor memory and dementia.
Food Sources
Vitamin B-12 is naturally found in animal products. Some plant-based foods, such as cereal, contain vitamin B-12 through fortification. Beef liver contains the highest amount of vitamin B-12 with 48 mcg in one slice. Fried clams are also a good source of vitamin B-12 with 34.2 mcg in a 3-oz. serving. One serving of fortified breakfast cereal contains 1.5 to 6 mcg of vitamin B-12. One cup of plain yogurt can also meet your needs with 1.4 mcg per serving. If you follow a vegan diet, someone who does not eat any meat products, you need to make sure you include foods fortified with vitamin B-12 to meet your daily needs.
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