Many people are doing Veganuary this year (a campaign that inspires people to try vegan for January, and beyond), which is why I want to raise awareness of vitamin B12 as it mainly comes from animal foods.
This is a hugely important vitamin which helps keep the body’s nervous system and blood cells healthy and is involved in the synthesis of DNA – to name just three of its key functions.
What is vitamin B12?
Vitamin B12 is one of the vitamins in the B complex family and water-soluble.
It is the only vitamin containing an essential mineral (cobalt), hence also called cobalamin. It exists in a few different forms, with methycobalamin and 5-deoxyadenosyl cobalamin being used in the human body. Most supplements contain the form cyanocobalamin, which is converted in the body.
Vitamin B12 is synthesised by bacteria, including those in the human colon (although this is not absorbed) and is found only in foods of animal origin.
Due to B12 being protein-bound, the hydrochloric acid in the stomach needs to separate it first from the protein to which it is attached to (in the food), before B12 combines with the intrinsic factor (a glycoprotein produced in the glands of the gastric mucosa) and can then be absorbed in the lower ileum.
Functions & benefits
Vitamin B12 is essential for the metabolism and health of the central and peripheral nerve systems and normal brain function.
It has a vital role in the formation of healthy, mature erythrocytes (red blood cells) and the energy metabolism, which explain why it is regularly referred to as the “anti fatigue” vitamin.
The benefits of B12 to the central nervous system are numerous and include helping to maintain the health of nerve cells – including those needed for neurotransmitter signaling – and forming the myelin sheath around the nerves which is not only protective but also allows the transmission of electrical impulses.
Other primary roles include the methyl group transfer which facilitates the metabolism of folic acid and the synthesis of DNA. The growth of children is stimulated by this essential vitamin, as is the body’s use of proteins, fats and carbohydrates – which makes it vital for energy production.
Vitamin B12 also plays a role in heart health due its involvement in the maintenance of normal blood homocysteine levels alongside folate and vitamin B6, with raised homocysteine being a risk factor for cardiovascular disease.
B12 depletion and deficiency
Due to the vitamin’s functions explained above, low or depleted levels can lead to seriously affecting the nervous system and almost every cognitive function as well as digestive disorders and an increased risk for heart disease.
Impaired absorption (for example due to chronic inflammation of the stomach lining or lack of intrinsic factor) can lead to deficiency in older people.
Individuals with gastrointestinal disorders (like Celiac or Crohn’s disease for example) may be unable to absorb enough vitamin B12 from food to maintain healthy body stores.
Strict vegans are at increased risk of B12 dietary deficiency – which is something that needs to be taken into account when children are raised on a strict vegan diet.
Pernicious anemia however is not caused by an insufficient dietary intake of B12 but a medical autoimmune condition which results from impaired uptake of B12 due to the lack of intrinsic factor produced by the stomach lining. In pernicious anaemia red blood cells are enlarged (megaloblastic), and peripheral neurological damage develops. Anyone suffering from pernicious anemia receives lifelong B12 injections.
Symptoms of B12 deficiency
There are many different ways that B12 deficiency can manifest in the body and the list of possible signs and symptoms is not only long but also depends on age and genetic make up, as well as length and severity of the deficiency. B12 deficiency often goes undiagnosed for years.
The signs and symptoms associated with B12 deficiency include:
- mental changes (irritability, apathy, sleepiness, depression, memory loss, anxiety, personality changes)
- neurological signs and symptoms (pain, tingling and/or numbness, loss of position sense and balance, weakness, clumsiness, spasticity of muscles, vision changes)
- vascular problems (TIAs, CVA, coronary artery disease, palpitations)
- soreness of the mouth or tongue
- tiredness, chronic fatigue
- shortness of breath
- epigastric pain and constipation
- In infants, signs of a vitamin B12 deficiency include failure to thrive, problems with movement, delays in reaching the typical developmental milestones, and megaloblastic anemia.
The body stores B12 in the liver, so any deficiencies might take years to develop. This explains why “new” vegans often feel well for a couple of years but then start experiencing some of the above symptoms for seemingly inexplicable reasons – this could be because the body has used up all of the stored B12.
It is recommended that anyone following a strict vegan diet should get their B12 levels checked regularly and take a vitamin B12 supplements in order to ensure a sufficient intake. Please speak to your GP, health professional or nutritional therapist about this.
Recommended daily amount
The Reference Nutrient Intake for vitamin B12 in the UK (as part of a balanced diet) increases from birth and throughout childhood.
For males and females aged 15+ it is set at 1.5 micrograms (mcg) a day.
It’s fairly easy to get adequate amounts of B12 when following a healthy, balanced diet including meat, fish, eggs, and / or dairy products.
Vitamin B12 is considered safe and non-toxic but there can be some potential interactions with medication, so always speak to your healthcare provider before taking any dietary supplements. B12 can also be supplemented with injections or as an intramuscular vitamin.
Food sources of B12
The richest food sources of B12 are animal-derived and include:
- Meat (in particular organ meats)
- Fish (in particular sardines and mackeral) & shellfish
- Eggs
- Dairy products
Some foods are also synthetically fortified with B12, including:
- Non-dairy milks
- Nutritional yeast
- Cereals & grains
Nori (dried purple laver) is often mentioned as a good food source of B12 for vegetarians and vegans, and B12 can also be synthesised by some algae and bacteria – but the form and bioavailability of such forms have been disputed and might not be able to meet our body’s requirements.
Some mushrooms also show trace levels of vitamin B12, which is said to occur when considerable proportions of bacteria and actinomycetes in the soil synthesise B12 analogues.
As far as the animal derived food sources are concerned I generally recommend to consume grass-fed meat, wild-caught fish, and organic poultry and dairy (whenever possible).
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Also just a reminder to anyone doing Veganuary, and to all vegans out there – following a vegan diet doesn’t necessarily mean that it’s a healthy diet. There are lots of unhealthy and ultra-processed vegan foods out there, and switching from for example grass-fed meat to a processed vegan replacement can do more harm than good. I will do a blog about “how to be a healthy vegan” (focusing on nutrition) over the next couple of weeks with further info and recommendations.
Until then, stay healthy!
Carole x
