Vitamin B12 works together with folic acid to make healthy nerve and red blood cells. It is also needed to make the DNA, the genetic material of cells. People with B12 deficiency may experience tiredness, weakness, nausea, constipation, loss of appetite, and weight loss. Some people may also get numbness and tingle in the hands and feet, loss of balance, confusion, poor memory, and soreness of the tongue and mouth. Mothers with severe B12 deficiency have a higher risk of having a baby with learning difficulties and problems with movement or coordination. Unfortunately, treating severe B12 deficiencies does not fully repair the damage neurones.
The Department of Health recommended that people (including pregnant women) should have 1.5 ug a day of vitamin B12, and breastfeeding women should have 2.0 ug a day. However, Both the Vegan Society and Vegetarian Society recommend that people who do not eat animal products should have 3 µg of B12 a day by having B12 fortified foods or supplements as a regular part of their daily diet to achieve the recommended intake.
Vitamin B12 is only found in animal products (including milk) and foods where B12 is an added ingredient. Some algae (for example spirulina) and seaweeds (for example nori) have natural compounds that are like vitamin B12 but our bodies cannot use them. In addition, because they are similar to B12 they compete with it and can cause B12 deficiency in people who do not eat animal products.