Doctors have warned vegans to take the danger of vitamin B12 deficiency seriously – or potentially risk nerve damage, irreversible numbness and degeneration of the spinal cord.
The warning comes ahead of Veganuary, when more people take up the plant-based diet for the first month of the year.
Doctors are concerned many see the dangers of B12 deficiency associated with a vegan diet as a “myth” and urged them to read up on how to ensure they get enough of the vitamin if they continue past the first month.
However it takes several years to become deficient in the key vitamin, which can lead to neuropathy, nerve damage, irreversible numbness, and degeneration of the spinal cord.
Professor Tom Sanders, professor emeritus of nutrition and dietetics at King’s College London, said a small UK study on 172 vegan men had found about a fifth of participants were likely to be “seriously deficient”.
He said he was “really quite shocked” at the findings, from 2003, and “concerned that many vegans think it’s a myth”.
Prof Sanders said: “It’s something that can be easily avoided and what concerns me is that many new people becoming vegan are unaware of the need to combine sources of plant proteins and they are not aware of the need to make sure they’ve got adequate levels of B12, and you’ve got to be very careful, particularly in pregnancy, lactation and bringing up children to make sure you have adequate levels of micronutrients.”
He cautioned that replacing meat with options such as cauliflower or jackfruit was not a good alternative in terms of protein.
Many plant-based milks are also low in protein and should contain more vitamin B12, he said.
Prof Sanders also said that consumption of nitrous oxide, also known as laughing gas, among young people can cause vitamin B12 deficiency and “tip the balance to them getting serious neuropathy”.
He continued: “So it is a worry and don’t underestimate the damage it causes, it’s so easily avoided – B12 supplementation or eating foods fortified.
“I think the levels should be higher in plant milks than they are at the moment, and if they were three times higher then I don’t think there would be a problem.”
Tim Key, professor of epidemiology and deputy director of the Cancer Epidemiology Unit at the University of Oxford, said there was a concern about people tempted to go vegan for January without reading up on how to do so healthily.
He said: “You’re not going to get vitamin B12 deficiency in one month in Veganuary, but if people become vegan because of that and never actually bother to read up on what you need to eat as a vegan, I would be worried they don’t know about B12, and it’s clearly important – they just need a few sentences of education to say, ‘You must have B12 and you should be a bit sensible about protein sources’.
“I’m worried that doesn’t always happen with people becoming vegan now, they just think vegan food is OK, I’ll eat it, and that’s it.”
The experts, speaking at a Science Media Centre briefing, also warned that vegans should be aware of the rise of vegan “fast food”.
They said there has been a “rapid, large increase in processed foods that look like animal foods but are not really designed to be nutritionally equivalent or better”.
Additional reporting by Press Association