Vitamin B12 and manganese

Vitamin B12

Vitamin B12 is a B-complex vitamin that works with folate to make red blood cells to carry oxygen throughout the body. Vitamin B12 is also involved with many body chemicals and occurs in every body cell. This vitamin also helps your body use fatty acids and some amino acids.

A deficiency in vitamin B12 may cause anemia, fatigue, nerve damage, or sensitive skin. If extra folic acid is taken to treat or prevent anemia, this deficiency can be masked. Some individuals cannot absorb vitamin B12 because they are missing a chemical in their stomach lining, but injections can help treat this.

Strict vegetarians and infants of vegan mothers are at risk for developing a vitamin B12 deficiency. Older adults are also at risk for vitamin B12 deficiency because it isn't absorbed as well as we age. The Dietary Guidelines advises that people over 50 should consume vitamin B12 supplements or from fortified foods. Synthetic B12 from supplements or fortified foods is better absorbed than natural B12 in those individuals.

There are no symptoms from excess amounts of vitamin B12, but extra vitamin B12 to boost energy has no scientific basis.

The Recommended Daily Allowance (RDA) for adults is 2.4 micrograms (mcg) daily. For pregnant women, the RDA is 2.6 mcg daily and is 2.8 mcg daily for those who are breastfeeding. For the other RDA's, click here and scroll about halfway down.

Vitamin B12 comes from animal products, which is why vegetarians and vegans may need a supplement or to include more fortified foods. Fish, meat, poultry, eggs, milk, and other dairy are the best sources. Cereal is one example of a food that has been fortified with vitamin B12. For the sources and the amount of vitamin B12 they contain, click here and scroll 3/4 of the way down.

Manganese

Manganese is a mineral that serves as a part of many enzymes, helps in bone formation, and helps metabolize carbohydrates, fats, and proteins.

Manganese is in a lot of different foods, so a deficiency is unlikely. Consuming too much is rare as well. The Tolerable Upper Level Intake (UL) is 9 mg for teens and 11 mg for adults.

There is no RDA for manganese, but Adequate Intake (AI) levels have been established. Those daily AI's are:
Males age 14 to 18 - 2.2 mg
Females age 14 to 18 - 1.6 mg
Adult males - 2.3 mg
Adult females - 1.8 mg
Pregnant women - 2.0 mg
Breastfeeding women - 2.6 mg
For the other AI's, click here and scroll about 1/3 of the way down.

Whole grains, such as cereal, rice, bread and pasta, are the best sources of manganese. Some fruits and vegetables are also good sources. Tea is also a good source. For other sources and the amounts of manganese they contain, click here and scroll about halfway down.

Information is from the ADA Complete Food and Nutrition Guide and weblinks are from the Linus Pauling Institute, Oregon State University.