Assess the health of your digestive tract. A special digestive hormone called the intrinsic factor is needed for absorption of vitamin B-12. Certain illnesses and digestive disorders can hinder this process. Mild deficiencies of vitamin B-12 are fairly common, and are caused by inadequate intake, disease or a lack of the intrinsic factor. Common symptoms are fatigue and forgetfulness.
Severe deficiencies can lead to permanent nerve damage and a condition known as pernicious anemia.
Vitamin B-12 occurs naturally only in animal products, such as liver, beef, herring, mackerel, milk products, eggs and sardines. Vegans can get vitamin B-12 by taking supplements, eating or drinking fortified products, or adding certain yeast products to their diets. The optimal dose for adults is 10 to 100 mcg daily. Inc. How things get done. Use of this Web site constitutes acceptance of the eHow Terms of Use and Privacy .