The early 1930s was a time of great uncertainty. Prior to President Roosevelt, our nation was uncertain of its leadership. Investment uncertainty existed after economic collapse. Among the working class there was uncertain employment and therefore financial insecurity and doubt about whether daily necessities would be met. The nation gravitated to public figures such as sports heroes who provided inspiration as they struggled to persevere through the depression.

Baseball was the most popular sport in America during this time. Both New York Yankees, Lou Gehrig rose in Babe Ruth’s shadow. Gehrig became more than a baseball hero of the nation though. Unlike Babe Ruth, Gehrig approached baseball as a workman rather than a sport’s star, though he set several major league records. He was nicknamed “The Iron Horse” as a result of his reliability as a player and his steadfast work ethic. In 1939, however, Gehrig’s reliability gave way to a diagnosis of a rare disease, amyotrophic lateral sclerosis (ALS), an incurable neuromuscular illness now commonly referred to as Lou Gehrig’s disease. The unthinkable had occurred. He had been confidently walking on to ball fields for 16 years. Now his future was uncertain.

Though not a cure, vitamin B12 has been found to have a protective effect on neurons, giving it the potential ability to lengthen the lifespan of those with Lou Gehrig’s disease.1 Vitamin B12 plays a crucial role in the nervous system. It is needed in the formation of the protective sheath around nerve fibers that allow for successful nerve transmission. It plays an important role in cell division and the production of red blood cells. It is involved in the metabolism of fat and protein. Deficiency can impact risk of cardiovascular disease by impairing the function of the lining of arteries, which can lead to atherosclerosis.

Sufficient or Deficient?

While we do not require an abundance of B12, we do need to ensure adequate amounts. Deficiency can be disastrous to nerve, brain, and eye function. Generic symptoms like feeling tired, weak, constipation, loss of appetite, memory difficulties, numbness, and tingling in the hands or feet can all be associated with B12 deficiency.

Vitamin B12 is produced by some strains of bacteria. Absorption of B12 from our own intestinal bacteria is unsure as it occurs higher in the intestinal tract than where it is produced. Vitamin B12 is present in animal foods, such as meat, eggs, and dairy, but for those who are choosing to reduce these foods in their diet, adequacy is a concern. There is some evidence that dried green and purple laver (nori) contains vitamin B12.2 However, people who have relied on edible algae have been found to be deficient. Many foods thought to contain B12 contain either none, only trace amounts, or contain a form that is inactive in humans. It is commonly believed that fermented food is another source. Fermented food, however, is not a reliable source.

Those with gastrointestinal disorders, like celiac disease or Crohn’s, or those who have had weight loss surgery, may not be properly absorbing B12

Vitamin B12 deficiency is experienced even in those who consume animal-based diets, especially with age. One reason for this could be impaired absorption. Several factors could potentially affect absorption, but one is a lack of sufficient acid in the stomach. Medications that decrease stomach acid include proton pump inhibitors (PPIs) such as Prilosec, Nexium, and H2 blockers, such as Zantac and Pepcid, which are taken to relieve symptoms of acid reflux and stomach ulcers. One study found that individuals who took PPIs for more than 2 years had a 65 percent higher risk of B12 deficiency.3 Approximately 80 percent of PPIs in the United States are purchased without a prescription or physician evaluation of upper gastrointestinal symptoms.4 This is compounded by the fact that one out of three adults over age 50 have decreased stomach acid secretion. Bacterial overgrowth in unwanted regions of the gastrointestinal tract, such as the stomach and upper small intestine, can result from decreased stomach acid levels. Bacterial overgrowth was found in 53 percent of 47 outpatients taking omeprazole (20 mg/day) in a prospective study.5 As a result, the bacterial colony may actually use vitamin B12 rather than produce it, “further reducing the amount of vitamin B12 available.”6 Those with gastrointestinal disorders, like celiac disease or Crohn’s, or those who have had weight loss surgery, may not be properly absorbing B12 as well.

Certain medications such as Metformin, a common medication used for type 2 diabetes, can also impair absorption. It is estimated that chronic use of Metformin results in B12 deficiency in 30 percent of patients and could be a potential cause of neuropathy.7 The elderly may be more susceptible, as one study found that 53 percent of elderly in long-term care institutions with diabetes experienced B12 deficiency compared to 31 percent in diabetic patients not taking Metformin and 33 percent in the elderly without diabetes.8

What is considered to be the most reliable way of detecting deficiency or measuring B12 levels is to test methylmalonic acid (MMA). MMA accumulates in the blood with B12 deficiency, and consuming foods that contain active vitamin B12 causes those levels to drop. Many foods commonly believed to be good sources of vitamin B12 actually have no effect on MMA levels, which means those foods contain primarily inactive analogues.

Next month we will conclude our discussion of Lou Gehrig, vitamin B12, and supplementation so that we can B sure.

  1. Y. Izumi & R. Kaji, “Clinical trials of ultra-high-dose methylcobalamin in ALS,” Brain Nerve, 10/2007. 59(10):1141-7. (2007),
  2. F. Wanatabe, “Vitamin B12 sources and bioavailability,” Exp Biol Med, 11/2007, 232(10):1266-74,
  3. J. Lam et al, “Proton pump inhibitor and histamine 2 receptor antagonist use and vitamin B12 deficiency,” JAMA, 12/11/13, 310(22):2435-42.
  4. J. Heidelbaugh, “Proton pump inhibitors and risk of vitamin and mineral deficiency: evidence and clinical implications,” Therapeutic advances in drug safety, vol. 4, 3 (2013): 125-33. 
  5. Andrew C. Dukowicz, MD  et al, “Small Intestinal Bacterial Overgrowth: A Comprehensive Review,” Gastroenterology & hepatology, vol. 3, 2 (2007): 112-22,
  6. Vitamin B12, National Institute of Health,
  7. D. Bell, “Metformin-Induced Vitamin B12 Deficiency Presenting as a Peripheral Neuropathy,” South Med J, 103(3):265-7 (2010),
  8. Can’t access the website. C. Wong, , C.S. Leung, C.P. Leung,  & J. Cheng, , (2018). “Association of metformin use with vitamin B12 deficiency in the institutionalized elderly,” Arch Gerontol Geriatr, 79:57-62,.
Risë Rafferty, RDN
Health Educator at Light Bearers

Risë is a Registered Dietitian Nutritionist (RDN) and has been writing and teaching about health for many years. She loves the health message and takes great pleasure in seeing people thrive by the application of its principles. Her research and down-to-earth manner allow her to offer up the health message in both an intelligent and accessible manner. She and her husband, James Rafferty, have two children.