VITAMIN B12 RDA

Sources of Vitamin B12

Watch for these signs of Vitamin B12 Deficiency

Fatigue
Weakness
Weight loss

Constipation

Infertility
Vision problems
Loss of hearing and tinnitus

Alcoholism
Impotence
Incontinence
Hyperpigmentation and hypopigmentation
(dark and light patches in the skin)
Neuralgia, neuritis and bursitis
Anemia, including pernicious anemia
Spinal cord degeneration
Psoriasis and other skin problems
Brain degeneration
Insomnia
Any emotional disorder up to and including insanity

Poor growth/failure to thrive in infants
Inflamed tongue
Premature grey hair
Disturbed carbohydrate metabolism
Numbness and tingling in the hands and feet
Irrational or chronic anger
Violent behavior
Lack of balance/abnormal gait
Combat fatigue

This presents a serious problem for vegetarians and vegans alike as they avoid eating animal products where vitamin B12 is found.  Vitamin B12 is found almost predominately in animal foods such as kidney, meat, liver, shellfish, fish, milk, and eggs. The source of Vitamin B12 is bacteria found in nature. Bacteria is the only creature able to produce Vitamin B12. Bacteria produce Vitamin B12 in the colon of humans and animals.
However not much vitamin B12 is absorbed across the wall of the colon so therefore it is essential that humans get B12 from animal foods.  Eggs are not a good source of B12 for vegetarians as they contain substances that block absorption of B12. Milk is a good source of B12 for vegetarians. Most vegetarians and vegans are recommended to take routine vitamin b12 supplementation. Some people can go longer on a vegatarian diet than others before they develop b12 deficiency.

Vitamin B12 is one of the very most important nutrients we get from animal foods. Vitamin B12 is a compound that is red in color because of the presence of cobalt. Absorption of Vitamin B12 is a complex process which can be problematic for many. For it to be absorbed effectively, B12 attaches to a protein known as intrinsic factor which is secreted in the stomach. Vitamin B12 binds with intrinsic factor and travels through to the small intestines. Once in the bloodstream, B12 binds to transport proteins. Enzymes release B12 from the protein complex and convert it to two forms- methylcobalamin and adenosylcobalamin. Deficiency in the enzymes can stop this conversion. Because there are so many potential blocks in the absorption process many people develop Vitamin B12 deficiencies even though they get plenty of Vitamin B12 in their diet.