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Action needed on vitamin B12 deficiency in people following plant-based diets

University of Surrey

vitamin B12

Vitamin B12 is an essential micronutrient which plays a role in supporting red blood cell production, energy, metabolism, and nerve function, but it is not found in plants.


Researchers are concerned that too many people are still not aware of the importance of preventing Vitamin B12 deficiency, particularly among high-risk groups such as vegans and many vegetarians. 

B12 is essential to the brain and nervous system, as well as for making red blood cells - and untreated deficiences can lead to permanent brain and nerve damage at any age. In early life, maternal B12 deficiencies can cause irreversible brain damage to the develping infant, leading to infant death or disability if severe - or in milder cases contributing to neurodevelopmental disorders such as autism. 

An expert group therefore recommends specialist advice on diet and supplements before pregnancy for all women following, or planning to follow a vegan diet.

Vitamin B12 is not found in plant foods - so vegans must take supplements, or use fortified foods, to avoid becoming B12 deficient. Vegetarians are also at risk unless their diet is well planned to include plenty of eggs and/or dairy products. 

But even if dietary intakes are adequate, poor absorption of B12 can be a problem for many people - particularly with increasing age. B12 absorption can be reduced or blocked by low stomach acid, or by autoimmune damage to the gut lining (pernicious anaemia). Over time, antacid medications for 'indigestion' can therefore raise risks for B12 deficiency, as can other commonly used drugs like metformin, prescribed for diabetes.

And if that weren't enough, B12 is inactivated by the anasethetic nitrous oxide - often known as 'laughing gas' - which is now very widely abused recreationally.

Symptoms of B12 deficiency are are all too easily overlooked or misdiagnosed unti it is too late - because they are many, varied and can differ widely between individuals - and can resemble symptoms of many other neurological, psychiatric or physical disorders. They include:

  • pain, tingling, numbness, vision problems, loss of normal motor control (including muscle stiffness or rigidity) or balance problems
  • fatigue, inattention, memory problems, 'brain fog', anxiety, depression, mood swings or symptoms indistinguishable from psychosis (e.g. hallucinations, delusions, agitation or paranoia)
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06/01/2022 - Medical Xpress

Plant-based diets (vegetarian or vegan) are becoming significantly more popular as people look to adopt a diet that is seen to be better for the environment, animal welfare, and/or personal health. Sales of plant-based foods have seen a 49 percent increase in Western Europe since 2018.

Scientists from around the world with expertise in food, nutrition, medicine, and health have formed a vitamin B12 research discussion group called cluB-12 to raise awareness of B12 deficiency and how it can be addressed. Vitamin B12 is an essential micronutrient which plays a role in supporting red blood cell production, energy, metabolism, and nerve function, but it is not found in plants.

Professor Martin Warren of the Quadram Institute in Norwich, UK, who helped initiate cluB-12, is keen that the public and policymakers are aware of the public health implications and measures needed to mitigate Vitamin B12 deficiency.

Vitamin B12, deficiency anemia can cause a wide range of symptoms. These usually develop gradually but can worsen if the condition goes untreated. Anemia is where you have fewer red blood cells than normal, or you have an abnormally low amount of a substance called hemoglobin in each red blood cell.

General symptoms may include: extreme tiredness (fatigue), lack of energy (lethargy), tinnitus, breathlessness, feeling faint, headaches, pale skin, noticeable heartbeats (palpitations), loss of appetite and weight loss.

The Quadram Institute's Professor Martin Warren said: "There is a hidden epidemic of vitamin B12 deficiency among vegetarian and vegan populations and this is a particular concern for women of child-bearing age. We are concerned that the current UK recommendations, for example, take no account of pregnancy and this urgently needs to be addressed."

"There are many good reasons to follow a planned and balanced plant-based diet but for a vegan diet especially you should be aware of the potential for nutritional deficiency and the need to take appropriate vitamin B12 supplements."

Dr. Kourosh R Ahmadi, co-author from the University of Surrey, said: "Millions of people across the globe are switching to a plant-based diet for a myriad of ethical reasons—whether it's because they have a love for animals or environmental reasons.

"Our paper is not about convincing people they are wrong for becoming vegans, but about making sure they are safe and don't sleepwalk into being B12 deficient.

"Furthermore, there clearly needs to be a global consensus on guidance on daily intake recommendations for vitamin B12—not just for adults but specifically for pregnant women and women who want to start a family."

Key recommendations for people choosing a vegan or vegetarian diet:

  • Take a daily supplement containing 4–7 micrograms of vitamin B12 with food
  • Monitor your vitamin B12 status - especially if you have not been taking supplements
  • Get expert advice to support planning of a plant-based diet, particularly if becoming vegan
  • Get expert advice if you're on a vegetarian diet and you are a) planning to become vegan, b) planning to become pregnant or are breastfeeding and c) older than 60

International recommended nutritional intakes

  • UK—recommended nutritional intake (RNI) for vitamin B12 is set at 1.5 micrograms a day for adults and no adjustment is made for pregnancy
  • U.S.—the RNI is 2.3 micrograms a day and increases to 2.6 and 2.8 a day for pregnant and breastfeeding women, respectively
  • EU–4 micrograms a day and increases to 4.5 and 5 for pregnant and breastfeeding women, respectively

People following a vegan diet are at much higher risk of vitamin B12 deficiency. Estimates suggest deficiency rates as high as 62 percent in pregnant women. In vegetarians, B12 deficiency is as high as 40 percent.

Research undertaken by the Food Databanks National Capability at the Quadram Institute also shows that vegan products in UK supermarkets do not commonly or adequately fortify their vegan food products with vitamin B12.