B12: Of Beef and Bacteria

Just as hamburgers, steaks, chicken wings, pork chops, and other meat products bring unique flavors and aromas to the dinner table, they provide many components necessary for human health.  In fact, meat and other animal products provide some nutrients not found in other foods.  Among those is cyanocobalamin, more commonly known as vitamin B12.

Vitamin B12 is produced by microorganisms that can be found in the environment and inside animals.  Those inside animals make the vitamin in the intestine, and the vitamin can then travel to other organs, muscles, and products (milk and eggs) which can then be incorporated in the human diet (Vitamin B12, n.d.).  Beef liver and clams are the best sources of the vitamin, followed by fish, poultry, meat, milk, eggs, and other dairy products (Office of Dietary Supplements [ODS], 2011).  Red meat is a particularly affordable and diversifiable source of B12.  For example, a single 100 g serving of red meat (such as a 3.5 oz. hamburger patty) can provide 66% of an adult’s daily need for the vitamin (McAfee et al., 2010).  If an insufficient level of vitamin B12 is maintained, weakness, weight loss, tiredness, confusion, loss of appetite, and other health problems may develop (ODS, 2011).  However, though some people may consume enough of the vitamin B12 through their diet, they may not be able to use it.  Vitamin B12 must first be separated from its bound protein and then affiliate with an “intrinsic factor” in the stomach before being absorbed (Vitamin B12, n.d.).  When dietary vitamin B12 cannot be utilized, a supplement is necessary to avoid a deficiency.

According to the National Institute of Health’s Office of Dietary Supplements, the amount of vitamin B12 people need to consume each day varies by age but is essential during all stages of life, as shown in Table 1 (2011).  Problems with metabolism, red blood cell formation, and nervous system performance can result from a vitamin B12 deficiency, and the best way to ensure adequate vitamin B12 levels is to incorporate a variety of animal products into the diet (New York Times, 2011). 

Table 1: Daily recommended amount of vitamin B12 in micrograms (mcg).  The daily recommended amounts increase due to age or special conditions such as pregnancy or lactation (ODS, 2011).

Life Stage	Recommended Amount
Birth to 6 months	0.4 mcg
Infants 7–12 months	0.5 mcg
Children 1–3 years	0.9 mcg
Children 4–8 years	1.2 mcg
Children 9–13 years	1.8 mcg
Teens 14–18 years	2.4 mcg
Adults	2.4 mcg
Pregnant teens and women	2.6 mcg
Breastfeeding teens and women	2.8 mcg

While adults can endure a vitamin B12 deficiency for several years before showing its symptoms, newborns can show its effects soon after birth (Dror & Allen, 2008).  In a healthy pregnant woman, vitamin B12 will travel to the placenta and then to the growing child (Vitamin B12, n.d.).  If the mother, unable to absorb the vitamin or, by choice or not, lacking vitamin B12 in her diet, maintains a low level of this vitamin before and during pregnancy, her unborn child will not receive enough of the vitamin (Dror & Allen, 2008).  In a study by Majchrzak and colleagues (2006) comparing B-vitamin levels in people with different diets, omnivores possessed adequate levels of vitamin B12 whereas vegetarians and vegans displayed inadequacies of the vitamin.  It could then be conjectured that pregnant women eating a balanced diet that includes meat, poultry, eggs, and dairy are much more likely to deliver enough B12 to their unborn children than women avoiding these foods.  Being unable to absorb vitamin B12, not having access to animal products, or choosing not to consumer animal products can cause irritability, failure to thrive, poor development, and apathy in newborns if the mother does not receive a vitamin B12 supplement.

In conclusion, people who enjoy a variety of protein sources including red meat, poultry, eggs, and dairy and effectively absorb and use these food’ nutrients can avoid multitudes of deficiencies, especially that of vitamin B12.  Those who cannot absorb the vitamin, cannot obtain animal products, or choose not to consume animal products need to receive a vitamin B12 supplement to avoid a deficiency.  As for me, I am happy to obtain my vitamin B12 from a bacon-topped turkey burger or ham and cheese omelet rather than the encapsulated products of a bacteria culture. 

References

Dror, D.K., Allen, L.H.  (2008).  Effect of vitamin B12 deficiency on neurodevelopment in infants: current knowledge and possible mechanisms.  Nutrition Reviews 66(5), 250-255. DOI: 10.1111/j.1753-4887.2008.00031.x

Majchrak, D., Singer, I., Maenner, M., Rust, P., Genser, D., Wagner, K.H., Elmadfa, I.  (2006).  B-vitamin status and concentrations of homocysteine in Austrian omnivores, vegetarians and vegans.  Annals of Nutrition and Metabolism 50(6), 485-491. DOI: 10.1159/000095828

McAfee, A.J., McSorley, E.M., Cuskelly, G.J., Moss, B.W., Wallace, J.M.W., Bonham, M.P, Fearon, A.M.  (2010).  Red meat consumption: An overview of the risks and benefits.  Meat Science 84(1), 1-13.

New York Times (2011, February 15).  Vitamin B12.  Retrieved from http://health.nytimes.com/health/guides/nutrition/vitamin-b12.

Office of Dietary Supplements (2011, June 24).  Dietary Supplement Fact Sheet: Vitamin B12.  Retrieved from http://ods.od.nih.gov/factsheets/VitaminB12-QuickFacts/.

Vitamin B12 – Compound Summary. (n.d.)  In PubChem Compound.  Retrieved from http://pubchem.ncbi.nlm.nih.gov/summary/summary.cgi?cid=16212801&loc=ec_rcs