(Conversation) – For several months during the summer of 2022, my dog Scout threw up at 3 am almost every day. If you have a dog, you know the sound. And each time, she swallowed her mess before I could get to her, making diagnosis of the cause difficult.
The vet and I eventually settled on my hydrangeas as the source of the problem – but keeping Scout away from them didn’t work. She started looking tired all the time – very disturbing in a typical yellow Lab puppy.
Then one day Scout threw up a hairball – but not just any hairball. In dogs, hair normally passes easily through the digestive system, but this ball of hair was wrapped around a brillo pad that was too large to move. After this foreign object was removed, the nocturnal vomiting stopped. Scout still needed treatment, however, for a different and surprising reason: The object had blocked a step in her body’s absorption of vitamin B12. B12 is an essential nutrient involved in the proper functioning of blood cells, nerves and many other critical processes in the body.
I am a registered dietitian and I teach nutrition and food science in college students, but I still missed the B12 deficiency that was causing my puppy fatigue. Doctors can just as easily be blind to it in humans – even though B12 deficiency is a common health problem affecting a 6% to 20% of the American population.
B12 is scarce in the diet and is found only in foods of animal origin. Fortunately, people only need 2.4 micrograms of B12 per day, which is equal to one ten millionth of an ounce – a very, very small amount. Without adequate B12 in the body, overall health and quality of life are negatively affected.
signs and symptoms
A major symptom of B12 deficiency is fatigue – a level of tiredness or exhaustion so profound that it affects daily life activities.
Other symptoms are neurological and may include tingling in the limbs, confusion, memory loss, depression and difficulty maintaining balance. Some of these it can be permanent if the vitamin deficiency is not addressed.
However, since there can be so many causes for these symptoms, healthcare providers may overlook the possibility of a B12 deficiency and fail to screen for it. Furthermore, a healthy diet may seem to rule out any vitamin deficiency. Case in point: Because I knew Scout’s diet was healthy, I didn’t consider B12 deficiency to be the source of her problems.
How B12 is absorbed
Research is clear that people who consume plant-based diets should take B12 supplements in amounts typically provided by standard multivitamins. However, the hundreds of millions of Americans who consume B12 may also be at risk because of conditions that may prevent their bodies from absorbing B12.
Absorption of B12 is a complex multi-step process which begins in the mouth and ends at the distal end of the small intestine. When we chew, our food is mixed with saliva. When food is swallowed, a substance in the saliva is called R-protein – a protein that protects B12 from destruction by stomach acid – travels to the stomach with food.
Specific cells in the lining of the stomach, called parietal cells, secrete two substances that are important for the absorption of B12. One is stomach acid – it separates the food and B12, allowing the vitamin to bind to the R protein in saliva. Another substance, called intrinsic factor, mixes with the contents of the stomach and travels with them to the first part of the small intestine – the duodenum. Once in the duodenum, pancreatic juices release B12 from the R protein and deliver it to intrinsic factor. This pairing allows B12 to be absorbed into cells, where it can then help maintain nerve cells and form healthy red blood cells.
A B12 deficiency usually involves a breakdown at one or more of these points in the absorption pathway.
Risk factors for B12 deficiency
Without saliva, B12 will not bind to the salivary R protein and the body’s ability to absorb it is hindered. And there are hundreds of different ones drugs that can cause dry mouth, resulting in very little saliva production. They include opioids, inhalers, decongestants, antidepressants, blood pressure medication AND benzodiazepineslike Xanax, it is used to treat anxiety.
The last three categories alone easily account for 100 million prescriptions in the US each year.
Another possible contributor to B12 deficiency is low stomach acid. Hundreds of millions of Americans receive anti-ulcer medications that reduce stomach acids that cause ulcers. Researchers have strongly linked the use of these drugs with B12 deficiency – although this possibility may not outweigh the need for medication.
Stomach acid production it can also decrease with aging. More than 60 million people in the US are over 60 years oldand about 54 million are over the age of 65. This population faces a higher risk of B12 deficiency – which can be further increased by the use of acid-reducing medications.
Production of gastric acid and intrinsic factor by specialized parietal cells in the stomach is critical for B12 absorption to occur. But damage to the stomach lining can prevent the production of both.
In humans, damaged gastric mucosa results from gastric surgery, chronic inflammation or pernicious anemia – a medical condition characterized by fatigue and a long list of other symptoms.
Another common cause of B12 deficiency is insufficient B12 pancreatic function. About a third of patients with poor pancreatic function develop a B12 deficiency.
And finally, Metformin, a drug used by approx 92 million Americans for the treatment of type 2 diabetes, has been associated with B12 deficiency for decades.
Treatment for B12 deficiency
While some health care providers routinely measure levels of B12 and other vitamins, a typical well-check includes only a complete blood count and a metabolic panel, neither of which measures B12 status. If you have possible symptoms of B12 deficiency and also have one of the risk factors above, you should see a doctor to be tested. A proper laboratory examination and discussion with a physician are necessary to detect or rule out whether insufficient B12 levels may be at play.
In the case of my dog Scout, her symptoms led the vet to run two blood tests: a complete blood count and a B12 test. These are also good starting points for people. Scout’s symptoms went away after several months of taking oral B12 supplements that also contained an active form of the B vitamin folate.
In humans, the type of treatment and the length of recovery depend on the cause and severity of the B12 deficiency. Full recovery can take up to a year, but is very possible with proper treatment.
Treatment for B12 deficiency it can be by mouth, applied under the tongue or administered through the nose, or it can require different types of injections. A B12 supplement or balanced multivitamin may be enough to correct the deficiency, as it was for Scout, but it’s best to work with a health care provider to ensure proper diagnosis and treatment.
