A vegan man whose arms went numb and who had trouble speaking had vitamin B12 levels so low they were 'undetectable'

• A man who ate a vegan diet for 20 years had 'undetectable' vitamin B12 levels, according to a report.
• The man's arms went numb because the deficiency affected his nervous system.
• People who don't eat animal products should take B12 supplements to prevent nervous system damage. 

A man who ate a "strict" vegan diet for 20 years developed a vitamin B12 deficiency that caused him to struggle to find the words to speak and numbness in his arms, according to a report. 

Vitamin B12 — found naturally in meat, eggs, and dairy products but available as a supplement — is essential for nerves and the red blood cells that carry oxygen around the body. A vitamin B12 deficiency can cause irreversible nervous system damage if left untreated for more than six months after symptoms begin.

The unnamed man, 39, went to doctors after he experienced numbness and tingling in his arms — from the elbows to his fingertips — for four days, doctors and medical students wrote in a report published in the Cureus Journal of Medical Science on September 16.

For the past seven months he'd had trouble finding words, felt confused, and had intermittently blurry vision, they said. 

He also felt unbalanced, lightheaded, breathless, and more tired than usual, the health professionals, who work in Atlanta, said.

Symptoms of vitamin B12 deficiency vary and include: tingling arms or legs, trouble walking, fatigue, nausea, a fast heart rate, and irritability. Numbness happens because of the effects on the nervous system. 

The man had 'undetectable' vitamin B12 levels

Investigations revealed that the man had "undetectable" vitamin B12 levels and depleted levels of red and white blood cells and platelets. 

Vitamin B12 deficiency typically has two causes: because a person isn't eating enough foods containing it or malabsorption because of conditions like celiac disease and pernicious anemia.

In this case, the man had followed a vegan diet for 20 years without taking vitamin B12 supplements.

B12 deficiency is becoming increasingly common as more people go vegan 

Most people in the US eat enough vitamin B12, National Institutes of Health data suggests. However, vegans and those who haven't eaten eggs, dairy, and meat for more than five years are at risk of vitamin B12 deficiency, the British Dietetic Association states. It recommends that long-term vegetarians and vegans get their vitamin B12 status checked and take supplements of around 10 micrograms per day as required. 

According to the report, severe B12 deficiency, like the man's, is rare but becoming increasingly common as more people adopt a vegan or vegetarian lifestyle. 

Early treatment of vitamin B12 deficiency is vital to prevent irreversible nervous system damage, the doctors wrote. 

Doctors treated the man with vitamin B12 injections and blood transfusions

The doctors treated the man in hospital with three blood transfusions, and daily vitamin B12 injections for two days. 

He then took vitamin B12 injections every day for five days at home, followed by an injection once a week for four weeks, and then once a month.

According to the report, his word-finding difficulties improved after one day of treatment, and his co-ordination, tiredness, and breathlessness improved after two days.

After one month, his confusion was "completely better," but he still had some numbness in his left hand, the doctors said.

After two months, blood tests found that his vitamin B12 levels were back to normal.