Introduction
This is partly adapted from a great factsheet from Nutrigold, so thank you to them.
11% of vegan women of childbearing age that were surveyed were clinically deficient in B12. But, according to research, so are up to 90% of the elderly, 62% of pregnant women, 25%–86% of children, and 21%–41% of adolescents.
Vitamin B12 is a crucial vitamin required for the production of energy, metabolism, red blood cell formation, neurological function, DNA synthesis and maintaining healthy homocysteine levels. Despite being water-soluble, it is stored in the liver, so any symptoms from deficiency, such as from chronically low dietary intake, can take up to five years to show up; it’s a slow, insidious build up usually, so you don’t really notice what’s going on.
Vitamin B12 exists in several forms. Methylcobalamin and adenosylcobalamin are two natural forms that are the most active and usable in the body. The other inactive forms are hydroxocobalamin and cyanocobalamin – those have to be metabolised into the two active forms to be used. Some people have issues doing this metabolism and that causes absorption problems.
Why you might not be absorbing B12 well enough
B12 digestion and absorption is a complex process and requires enough stomach (hydrochloric) acid, intrinsic factor (a glycoprotein secreted in the stomach) and proteases (enzymes that break down proteins and peptides).
Simply put, B12 is digested by pepsin (an enzyme secreted in the stomach), which is activated by hydrochloric acid, and then binds to intrinsic factor for absorption in the small intestine. So, you can see, if your B12 is low, could it be lack of stomach acid, lack of enzymes, a problem with intrinsic factor (usually autoimmunity) or poor absorption by the villi in the small intestine (coeliac disease, Crohn’s etc).
Some people have pernicious anaemia, an autoimmune disease that affects the stomach lining, leading to the destruction of specialised cells in the stomach called parietal cells and a failure to produce sufficient intrinsic factor, resulting in Vitamin B12 malabsorption and eventually deficiency.
Older adults, who often suffer from decreased hydrochloric acid in the stomach (see here), and have gut problems such as H pylori infection or acid reflux may also have compromised absorption of B12. A big problem is caused by taking PPIs and antacid medication longer-term too. A similar problem happens with the diabetes medication metformin.
Low B12 symptoms
• Fatigue, weakness, poor exercise tolerance
• Constipation
• Loss of appetite and weight loss
• Soreness of the mouth or tongue
• Neurological conditions, such as numbness and tingling of the hands and feet
• Difficulty with balance
• Depression
• Confusion
• Poor memory and dementia (e.g. Alzheimer’s disease)
• Low bone mineral density
• Megaloblastic anaemia (i.e. formation of large and structurally abnormal red blood cells, look for high MCV levels on blood tests)
Other signs and symptoms of having a B12 deficiency may include infertility, pale skin, dizzyness, irregular heartbeat, cold hands and feet, and shortness of breath.
The neurological symptoms can occur without the presence of anaemia, thus early detection is important to avoid irreversible damage. Deficiency is also commonly misdiagnosed because symptoms can mimic other conditions. Many people with low intake of B12 also show restricted activity of B12-related enzymes, leading to elevated homocysteine levels, which have been linked to increased risk of heart disease and stroke. So, measuring homocysteine levels can be a good clue to B12 problems.
Large intake of folic acid – common in vegan diets due to high levels of plant matter – can mask the damaging effects of B12 deficiency by correcting anaemia without addressing the neurological damage that occurs. High folic acid may even exacerbate Vitamin B12 deficient anaemia and cognitive symptoms so it’s recommended not to exceed 1000mcg daily of folic acid in healthy adults without balancing Vitamin B12 intake and to check Vitamin B12 levels (see below). The practice of adding folic acid to food may present problems here actually – we should also be making sure people get enough B12.
Foods high in B12 and can we get enough from plant sources?
Vitamin B12 is synthesised in the body by bacteria in the gut so you’re not going to find much in plant sources. Most in our diets comes from fish, meat, poultry, eggs, milk, with useful amounts also from nutritional yeast and even Marmite. Though some bacteria in the small intestines produce B12, it isn’t enough to maintain adequate status in humans.
According to Jack Norris, RD, a vegan expert and co-author of Vegan for Life: Everything You Need to Know to Be Healthy and Fit on a Plant-Based Diet, there are no reliable sources of B12 in plants, contrary to many rumours about sources such as tempeh, seaweeds, and organic produce. Plants have no B12 requirement; therefore, they don’t have any active mechanisms to make or store it. When you find B12 in plants, it’s due to contamination and so isn’t a reliable source.
Many types of seaweed have B12 through their symbiotic relationship with cobalamin-producing bacteria; however, the evidence isn’t clear that this form is active B12 in humans. And fermented foods, such as tempeh, aren’t fermented through B12-producing bacteria so they aren’t a reliable source of B12.
Rumours about bacteria on the surface of organic produce producing B12 haven’t been verified. “Chlorella may improve B12 status, but it’s by such a small amount that I wouldn’t rely on chlorella for B12,” Norris adds. So that’s not to say that these food sources are not worth taking. On the contrary, spirulina, chlorella, seaweed and tempeh contain many other nutritional benefits to enjoy; it’s just they aren’t a reliable source of Vitamin B12.
This means that vegetarians – especially vegans – are at risk of Vitamin B12 deficiency, which may take years to manifest. In fact, there’s a high prevalence of low serum Vitamin B12 among vegetarians, in particular vegans, where prevalence ranges at levels between 43% and 88%.
In a review paper of the National Diet and Nutrition Surveys in the BMJ, the researchers found that 11% of vegan women of childbearing age that were surveyed were clinically deficient in B12 and had significantly higher folate intake through dietary sources. Going back as far as 1955, studies have shown that vegans have experienced Vitamin B12 deficiency. In addition, B12 crosses the placenta during pregnancy and is present in breast milk, thus, if the mother doesn’t receive adequate B12 intake, infants may suffer from B12 deficiency, which can lead to severe, permanent neurological damage.
But, if the National Diet and Nutrition Surveys suggest that 89% of vegans have B12 in the expected blood serum range, then what’s the problem for the majority with reportedly okay levels? It all comes down to the detection range of the test, which is believed to be too narrow to pick up more subtle B12 deficiencies, as well as the body’s ability to store B12 for a few years, although the levels will eventually decline if adequate dietary intake isn’t followed. Many people following a vegan or vegetarian diet that have not considered B12 support will have subclinical changes manifesting from dwindling B12 stores that may ultimately lead to long-term health consequences if not addressed.
But it’s not just vegetarians and vegans that are at risk of B12 deficiency. Studies have also found B12 deficiency in different populations including up to 90% of the elderly, 62% of pregnant women, 25%–86% of children, and 21%–41% of adolescents. Some big ranges there! Either way, the message is that many people are likely low in B12, despite crap testing.
Testing – properly – for B12
It’s surprisingly difficult to test properly for B12. Most often it is tested using serum, but that can be pretty misleading. I would always advise testing the active B12 so you can see what is actually available for use by cells, not what is just kept in the blood to maintain the status quo level. Bear in mind that, if you test with serum, low B12 may indicate a deficiency, but it could also be because of low levels of B6 and/or folate as they all work together, so it’s difficult to separate them out.
You can also check MMA levels in a functional test like the Metabolomix or via homocysteine, both of which will also indicate a probable B12 issue.
Methylmalonic acid (MMA) is a compound produced in very small amounts during amino acid metabolism. Increased production of MMA detected in the urine occurs in Vitamin B12 deficiency. This is because B12 acts as a coenzyme, promoting the conversion of methylmalonyl CoA to succinyl CoA. Elevated serum homocysteine also indicates an imbalance in B vitamin and methylation cycle activity.
Organic acid urine tests can also detect Vitamin B12 deficiency.
Personally, I like my Anaemia test best because it checks for active B12, but also red cell folate (again serum is often misleading) and the other anaemia types.
You can see all the Nutrient Tests here.
How much B12 should I supplement?
Ok, so you’ve found you could do with more B12. What now?
The RDA for B12 in adults is a very low 2.4mcg per day, however it’s suggested that adults should supplement 10 to 50mcg Vitamin B12 additional to the daily diet and vegan adults 18 to 65 years old should consider a daily B12 food supplement boost of up to 100 to 1000mcg daily. Older people can supplement up to 1000mcg B12 daily.
These higher recommendations partly stem from the loss of B12 through food processing and pasteurisation, such as with most UK dairy products, and also because only around 50% of B12 from food is absorbed through a healthy gut – and a lot of people don’t have a healthy gut, to be honest!
What are the best B12 supplements?
Most crappier, cheaper-end (and some well-known, not-so-cheap!) supplements and multis only contain B12 as the inactive cyanocobalamin or hydroxycobalamin forms. This means the body then has to expend energy converting into the bioactive forms methylcobalamin and adenosylcobalamin, so it can be better to just make sure you’re taking the active forms in the first place – some people actually have trouble doing this enzymatic conversion anyway, so make sure it’s something you can absorb, I say!
That said, some people find they do better on either mixed forms or some of both types, so it pays to try a few if your levels are not coming up or you don’t feel the benefit. In general, I would always advise that you take a B complex or a multi with the full B complex in it and add extra B12 or folate etc on top as needed. This is because taking one isolated B vitamin upsets the complex, and they all work synergistically together.
Note that injections are usually of hydroxycobalamin form, so the inactive form. You can get methylcobalamin injections, but probably not through the NHS.
Nutrigold do a sublingual B12 tablet you put under your tongue. I give P this spray. A mixed active and inactive form here and a liposomal form full B Complex here. A good all-round multi with the B Complex in and the active forms of the B vitamins here.
There’s a really good paper on B12 in the BMJ here, which gives some good advice. The key takeaways are:
- Neurological symptoms from B12 deficiency may take months or years to resolve.
- Serum biomarkers like B12 or methylmalonic acid are not entirely useful in assessing or monitoring clinical improvement, and injection frequency should not be based on biomarker levels. [Use active B12 to assess, Ed]
- Self-administration of B12 injections can improve patient satisfaction and health outcomes.
- Oral supplementation may not meet the physiological needs until injections have resolved the deficiency. [That’s an important one to note – you may need injections first, then maintain with supplements, Ed]
In essence, Vitamin B12 levels are crucial to maintaining long-term health and it’s not always possible to regularly eat or absorb the high dietary levels of Vitamin B12 required. Age and dietary status are two of the main reasons for Vitamin B12 deficiency, especially if the main sources of meat and dairy are not included for ethical/health/environmental reasons, as with vegan and some vegetarian diets. Daily supplementation of up to 1000mcg B12 with bioactive methylcobalamin and/or adenosylcobalamin forms through the sub-lingual route helps to bypass the complex stomach and digestive absorption process and improve bioavailability.
B12 Resources
B12d, a charity in the UK for raising awareness of Vitamin B12 deficiency and treatment gives great advice. Start with the symptom checker and protocol ideas here – which may be handy to send to your GP!
Hope that B12 101 helps!
Retiring, but loads of help still here!
I have now retired from Purehealth, but I have left my site, books, newsletters etc all up so that you can still access all this lovely info from the last 30 years! I won’t be updating it now, but there is a LOT of really good info here still. Check My Favourites page for where to find info, supplements, tests, practitioners, courses and more. Anything I think could help. And Start Here if you’re not sure where to start with your symptom or condition.
Please continue to support me by using the links, which might give me a bit of commission and you some discounts, and you can buy me a coffee here if you feel moved to.
You can still follow me here.
Bless your cotton socks from me. Thanks for all your love, support and fun over the past 30-odd years. I will miss you, Micki x