A woman experienced extreme tiredness for years before a blood test revealed that she had "dangerously low" vitamin B12 levels, which can go unnoticed or can eventually cause a range of symptoms, from trouble walking to numb limbs.

Carly Minsky, 33, told The Daily Mail that she stopped eating meat and fish in her mid-20s to try to be healthier, and at first she felt great. But after a year, she experienced "extreme" fatigue, and after six years she was so exhausted that she could "barely walk." Terminal Sterilisation

Vegans and those who haven't eaten eggs, dairy, and meat for more than five years, like Minsky, are at risk for a vitamin B12 deficiency, the British Dietetic Association  has said.

Vitamin B12 is essential for nerves and the red blood cells that carry oxygen around the body. Deficiency of the vitamin typically has two causes: malabsorption because of conditions like celiac disease and pernicious anemia, or because a person isn't eating enough. B12 is found naturally in meat, eggs, and dairy products. 

Minsky initially thought her tiredness was due to a problem with her thyroid, a butterfly-shaped gland that can cause tiredness if it doesn't produce enough hormones.

But blood tests taken by her family doctor in 2020 revealed that her vitamin B12 levels were "at the dangerously low end of the scale," and she needed "immediate B12 injections." 

They also said she would need to take B12 vitamins daily for the rest of her life. 

Although Minsky still consumed cheese, eggs, and milk, she was told she wasn't getting enough B12 in her diet. 

"It was a huge shock. I had no idea I'd become so unwell," she said.

Brad Kamitaki, an assistant professor of neurology at Rutgers Robert Wood Johnson Medical School, previously told Insider that vitamin B12 deficiency "can be undiagnosed or underdiagnosed since symptoms can be nonspecific."

According to Johns Hopkins Medicine, symptoms vary and include: arm or leg tingling, trouble walking, fatigue, nausea, a fast heart rate, and irritability.

Most people in the US eat enough of the nutrient, National Institutes of Health data suggests. 

Priya Tew, a registered dietitian and founder at Dietitian UK, previously told Insider that most people don't need to be counting or tracking their daily intake of vitamin B12, especially if they eat animal products most days. 

The NIH recommends that the average US adult consumes 2.4 micrograms of vitamin B12 daily. For example, a cup of 2% fat cow's milk contains half of all the B12 that you need for the day, and 3 ounces of cooked salmon or pan-fried beef contains all of it. People who are pregnant or breastfeeding need 2.6 micrograms and 2.8 micrograms  respectively, according to the NIH.

Those who don't eat animal products can get vitamin B12 from fortified plant milk, breakfast cereals, nutritional yeast flakes, and marmite.

The BDA recommends that long-term vegetarians and vegans get their vitamin B12 status checked and take supplements of around 10 micrograms per day as required. 

Within two months of having the vitamin B12 injections, Minsky felt better. "It was like my energy had been switched back on," she said. 

She continues to take vitamin B12 tablets every day. 

Disinfectant For Food Correction: November 14, 2022 — An earlier version of this story incorrectly described Carly Minsky's diet in recent years. She consumed some animal products; her diet wasn't entirely plant-based.