Could It Be B12 Deficiency?

Vitamin B12 deficiency has been on my mind recently, because a number of my clients and friends have described to me symptoms experienced by themselves and/or their family members that sound like they could be caused by B12 deficiency. Signs and symptoms of vitamin B12 deficiency include fatigue, dizziness, irregular heartbeats, numbness or tingling in hands and feet, muscle weakness, nervousness/anxiety, personality changes, unsteady gait, and/or mental confusion or forgetfulness (“fuzzy thinking” often attributed to normal aging).

Vitamin B12 (also called cobalamin) is one of eight B vitamins. All B vitamins help the body convert food (carbohydrates) into fuel (glucose), which is used to produce energy. Vitamin B-12 is an especially important vitamin for maintaining healthy nerve cells. It also helps in the production of DNA and RNA, the body’s genetic material, so it’s important for the growth and repair of body tissues, including bone. Vitamin B12 works closely with folate/folic acid to help make red blood cells and to help iron work better in the body. Folate and B12 work together to produce S-adenosylmethionine (SAMe), a compound involved in immune function and the production of neurotransmitters (like serotonin, dopamine, and adrenalin) that affect mood and motivation. Vitamin B12, along with vitamin B6 and folate/folic acid work together to control blood levels of the amino acid homocysteine. High levels of homocysteine are associated with heart disease and inflammation.

B12 is produced in the large intestine of both humans and animals, but it cannot be absorbed from there and is excreted. Plant-eating animals obtain vitamin B12 primarily from plants contaminated with nitrogen-fixing, vitamin B12-producing bacteria that grow in roots and nodes of legumes and from plants contaminated with feces. Carnivorous animals receive their B12 by eating insects, other animals, or feces. Plants contaminated with B12-producing bacteria through fertilization with manure may also be a source of B12, but vegetables grown with chemical fertilizers  are unlikely to contain B12.

You can increase your B12 intake with additional B12-rich food sources (meat, fish, poultry, eggs, milk products), as well as with either oral dietary supplements or B12 injections. Your health care provider may recommend B12 injections or lozenges that you dissolve under your tongue, if your test results indicate inadequate absorption. These sub-lingual lozenges (methylcobalamin) are absorbed into your bloodstream, bypassing the gut. For vegans, the most reliable food sources of B12 are plant food products fortified with B12 and/or a B12 supplement.

Your Risk of B12 Deficiency Is Increased If

  • Your diet contains little or no food sources of B-12 (animal protein)
  • You have intestinal problems that interfere with B12 absorption:
    • lack of intrinsic factor (genetically vulnerable populations include those of Northern European or Scandanavian background)
    • gastric or intestinal surgery
  • You take medications that block absorption of B12 including:
    • antacids
    • metformin (prescribed to treat diabetes)
  • You have endocrine-related autoimmune disorders such as:
    • Type 1 diabetes
    • Hashimoto’s thyroiditis
  • You are an exclusively breastfed infant of a vegan mother
  • You are over age 60 years
    • not only because a low intake or poor absorption over many years could deplete liver stores
    • but also because stomach acidity tends to decrease with age (and this can lead to poor absorption of dietary and supplemental B-12)

You can assess your risk of vitamin B-12 deficiency using the B12 Deficiency Risk Score developed by Sally Pacholok, RN, BSN and Jeffrey J. Stuart, DO, authors of COULD IT BE B12?. If your risk score is high, ask your health care provider to evaluate your B12 status. B12 deficiency is generally assessed first with a fasting blood test (serum B12). Values less than 200 pg/ml indicate vitamin B12 deficiency. Older adults with vitamin B12 levels between 200 and 500 pg/ml may also have symptoms, and require further evaluation. Pacholok and Stuart recommend that any person over age 60 years with a high B12 Deficiency Risk Score and a serum B12 less than 1,000 pg/mL receive further evaluation. Deficiency should be confirmed by checking the level of a substance in the blood called methymalonic acid (MMA), which is elevated in B12 deficiency. A normal test result is less than 0.2 mcmol/L. MMA can also be measured in the urine in a non-fasting state. This test is used to diagnose a mild and early shortage of vitamin B12. The urinary MMA (uMMA) test is more sensitive than the serumB12 test, as it indicates true tissue B12 deficiency. Results are given in micrograms per milligram (mcg/mg). The normal range for a MMA-to-creatinine ratio in a urine sample is less than 3.8 mcg/mg per mg of creatinine. The creatinine ratio indicates that the MMA level has been normalized to take into account urine concentration.

Estimates of B12 deficiency rates in the US range from 5% to 15% depending on the population studied and the methods of diagnosis. The most recent national data from the Centers for Disease Control (CDC) on B12 status reported that approximately 2% of the population aged 1 year and older, and 4% of persons 60 years and older had serum B12 concentrations less than 200 pg/mL. This CDC data was published in 2008 (reporting on blood samples collected during 2003-2006), and it’s the most recent data available on a national US sample. Other smaller regional studies have reported higher rates of B12 deficiency. For example, the Framingham Offspring Study found up to 39% of US adults at risk for vitamin B12 deficiency (defined as serum vitamin B12 <350 pg/mL), while 16% fell below 250 mg/mL and 9% fell below 200 pg/mL. The Framingham study included 3,000 men and women of mostly Northern European background living in Massachusetts. The higher rates of B12 deficiency may have been related to race/ethnic background, as the CDC reported that non-Hispanic whites tended to have lower B12 levels than other groups studied.

For more information, the book COULD IT BE B12? An Epidemic of Misdiagnoses, 2nd ed., 2011, is an excellent resource, as is the website The website links to two films well worth watching. SALLY PACHOLOK is the story of Sally’s advocacy for B-12 assessment and appropriate and timely treatment when vitamin B-12 deficiency is either suspected or confirmed. Sally has personal experience with B-12 deficiency, because of her hereditary difficulty absorbing B-12. The documentary DIAGNOSING AND TREATING VITAMIN B12 DEFICIENCY provides additional information on B12 diagnosis and treatment, along with interviews of patients with B12 deficiency and with health care providers treating B12 deficiency. Considering the aging of the US population, as well as the popularity of vegan diets, the increasing use of medications that block B12 absorption, and the changing nutrient levels in the food supply, a greater effort to identify and treat B12 deficiency is urgently needed.

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