Vitamin B12, a water-soluble vitamin also known as cobalamin, plays a role in numerous biochemical reactions and neurological functions in your body, including DNA synthesis.1 Your body can’t make vitamin B12 on its own, so it must be obtained via your diet or supplementation.

A deficiency can be serious and leads to a number of related changes, including personality disturbances, irritability and depression, along with a wide range of symptoms, including joint pain, “pins and needles” sensations, numbness and shortness of breath.2

One of the lesser known symptoms, however, may affect your voice. If you frequently experience hoarseness, a vitamin B12 deficiency could be to blame.

Hoarseness, Vocal Fold Palsy Linked to B12 Deficiency

Researchers from the department of nutrition science at East Carolina University reviewed 89 case studies of vitamin B12 deficiency, looking for causes, clinical manifestations and outcomes.3 Neurological, psychiatric, oral, dermatological and other “rare signs and symptoms” were reported, signaling just how varied the symptoms can be.

One of the case studies involved a 61-year-old man who suffered from vitamin B12 deficiency as a result of excessive alcohol consumption.4 His symptoms included gradually progressive hoarseness along with vocal fold palsy.

Vocal fold palsy occurs when one or both vocal folds become paralyzed and do not move properly. If one vocal cord does not move properly, it can lead to a hoarse voice, whereas if both vocal folds aren’t working, it can cause trouble with breathing.5

Typically, vocal fold palsy is related to surgical procedures, such as thyroid surgery or carotid artery surgery, or neck or chest tumors, but often the cause is unknown. In the original case report, which was published in The Journal of Laryngology & Otology in 2011, the researchers wrote:6

“A 61-year-old man presented to the emergency medical ward with an eight-week history of gradually progressive hoarseness and weakness of both lower limbs … The patient’s hoarseness was constant in nature, requiring repeated throat-clearing.”

He was treated with vitamin B12 replacement therapy, which resolved his symptoms:7

“… At follow up the patient’s voice and vocal fold function were noted to have improved. Both his voice and lower limb function continued to improve. Over the following three months, the patient made a full recovery, mirroring the normalization of his serum B12 levels.

We believe that this case demonstrates a strong relationship between vitamin B12 deficiency and vocal fold palsy”

Metformin Linked to B12 Deficiency, Hoarseness

In another case, a 55-year-old man with Type 2 diabetes also suffered from hoarseness, leading him to visit an otolaryngology (ear, nose and throat) clinic. Bilateral vocal fold paralysis was detected as a result of vitamin B12 deficiency, and according to the researchers, the condition resolved after his vitamin B12 levels increased:8

“Hoarseness of the patient progressively recovered after a month of treatment … After 3 months, the patient’s neuropathy complaints were repaired and the vocal fold were evaluated as normal.”

In this case, the man had been taking insulin, valsartan and metformin for five years. Metformin, a diabetes drug, has previously been linked to vitamin B12 deficiency. In one study, average vitamin B12 levels were lower among those taking metformin, and 4% were deficient compared to 2% in the placebo group.9

Further, nearly 20% of those taking metformin had borderline low vitamin B12 levels compared to 10% of those taking a placebo. More people in the metformin group were also anemic, which is associated with vitamin B12 deficiency.

The case-study researchers noted, “Physicians should be kept in mind that long term use of metformin could result vitamin B12 deficiency when assessing the etiology of vocal fold paralysis.”10

The Journal of Laryngology & Otology researchers also noted that it’s important for clinicians to consider vitamin B12 deficiency in the case of vocal fold palsy, stating, “It is important to consider vitamin B12 deficiency as a cause, as speedy identification and treatment can help prevent permanent neurological damage.”11

Some Vitamin B12 Deficiency Symptoms May Be Missed

The symptoms of vitamin B12 deficiency can be subtle or mirror other conditions, putting them at risk of being overlooked or misdiagnosed by clinicians. One of the effects of deficiency is a blood condition called megaloblastic anemia. It causes the bone marrow to release immature blood cells,12 which are unable to deliver adequate amounts of oxygen to the body. The result is fatigue and pale skin.

Those with megaloblastic anemia may also develop jaundice, a slight yellowing of the skin or eyes. Some with vitamin B12 deficiency also report experiencing eye twitching or eyelid spasms. In the featured study, a 74-year-old woman with B12 deficiency also experienced blurred vision, along with gait disturbances and problems with balance.13

Mental health problems can also be a sign of not enough B12, and it’s been observed that up to 30% of patients hospitalized for depression may be B12 deficient,14 while among the elderly with depressive disorders, those with B12 deficiency may be 70% more likely to experience depression. Those researchers went so far as to say that vitamin B12 may be causally related to depression.15

Vitamin B12 May Be Useful for COVID-19

B vitamins also play an important role in cell functioning, energy metabolism and immune function, leading one group of researchers to suggest that they could be useful for treating COVID-19, and vitamin B status should be assessed in COVID-19 patients.

“Vitamin B assists in proper activation of both the innate and adaptive immune responses, reduces proinflammatory cytokine levels, improves respiratory function, maintains endothelial integrity, prevents hypercoagulability and can reduce the length of stay in hospital,” researchers wrote in the journal Maturitas.16

In terms of vitamin B12, specifically, it modulates gut microbiota, and low levels may lead to increased inflammation and oxidative stress. A study also suggested that vitamin B12 supplements may reduce COVID-19-related organ damage and symptoms.17

Researchers with the Singapore General Hospital and Duke-NUS Medical School also set out to determine if a combination of vitamin D, magnesium and vitamin B12 would improve outcomes among COVID-19 patients aged 50 and older.

Seventeen patients received oral vitamin D3 (1,000 IU), magnesium (150 milligrams (mg)) and vitamin B12 (500 mcg) — together known as DMB — upon admission for a median of five days while 26 patients who did not receive DMB served as the control group.18

Significant benefits were seen among the DMB group, with only 17.6% requiring initiation of oxygen therapy during their hospitalization, compared to 61.5% of those in the control group. The requirement for oxygen is associated with an increased risk of needing intensive care, and the DMB group also benefited in this area.

Among those in the DMB group who required supplemental oxygen (three out of the 17 patients), two required ICU admission while one did not. Among the control group, all of those who needed supplemental oxygen required further ICU support. Nine of the DMB patients were given the combination within the first week of the onset of symptoms, and only one among them required oxygen therapy.

The researchers explained that vitamin D, magnesium and vitamin B12 present a unique three-pronged approach for tackling COVID-19, noting, “Vitamin B12 is essential in supporting a healthy gut microbiome which has an important role in the development and function of both innate and adaptive immune systems.”19

Who’s at Risk of Vitamin B12 Deficiency?

It’s been suggested that nearly two-fifths of Americans may have lower than ideal B12 levels, with 9% deficient and 16% below 185 pmol/L, which is considered marginally deficient.20 While vegetarians and vegans are susceptible since B12 is derived from animal products, even meat eaters may be deficient, as problems with absorption are common.

B12 is tightly bound to proteins and high acidity is required to break this bond. Some people may not have sufficient stomach acid to separate the B12 from the protein. Advancing age may also diminish your ability to absorb the vitamin from food and increase your risk of deficiency, as may any of the following scenarios:

People who regularly drink alcohol, as B12 is stored in your liver.

Anyone with an autoimmune disease like Crohn’s or celiac, which may prevent your body from being able to absorb B12.

People who drink more than four cups of coffee daily are more prone to vitamin B deficiencies than non-coffee consumers.21

Those who’ve had gastric bypass surgery and therefore have altered digestive systems, as this may impair B12 absorption.

People exposed to nitrous oxide (laughing gas), which can wipe out whatever B12 reserves you may have in your body.

Adults over 50, because as you grow older, your ability to produce intrinsic factor decreases.

People with helicobacter pylori infection. Intrinsic factor is a protein made by stomach cells that’s necessary for B12 absorption. H. pylori bacteria can destroy intrinsic factor, thereby preventing B12 absorption.

People who take antacids, which have a tendency to interfere with B12 absorption, especially over time.

Patients who take metformin for low blood sugar, as the drug interferes with B12 absorption, doubling your risk of deficiency.22

Anyone taking a proton pump inhibitor (PPIs) like Prevacid or Nexium or H2 blocker such as Pepcid or Zantac. Research shows taking PPIs for more than two years increases your risk of B12 deficiency by 65%.23

Women taking birth control pills for an extended period of time, as the estrogen impairs absorption.24

People who have taken antibiotics, as these drugs have been shown to induce vitamin B12 deficiency.25

In adults, B12 deficiency can develop in about six years, which is how long it takes to deplete your body’s B12 stores.26 So, it’s important to be aware of your intake and catch a B12 deficiency early, as impaired brain and nerve development can be very difficult to correct once the damage is done.

Regularly eating B12-rich foods, such as grass fed beef liver, wild rainbow trout and wild sockeye salmon, is important to maintain adequate levels, but if you suspect you may be deficient, weekly B12 shots or a high-dose, daily supplement may be necessary.

Methylcobalamin, which is the naturally occurring form of vitamin B12 found in food, is more absorbable than the cyanocobalamin, which is the type found in most supplements.27



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