Be sure about B12

| Post published on March 14, 2016
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Vitamin B12 is involved in many important functions. It helps make red blood cells and keeps the nervous system healthy. A deficiency can lead to serious problems, especially in the young. Vegans and ALL adults over 50 – even meat eaters – should get their B12 from supplements or fortified foods.

How much do we need?

The UK recommended intake is 1.5μg (micrograms) of B12 per day. In the US it is slightly higher at 2.4μg. In 2015, the European Food Safety Authority set a new ‘adequate intake’ of 4μg per day. Viva! Health recommends an intake of 5μg per day from fortified foods with the regular use of supplements to ensure topping this up.

Absorption – a complex issue

Absorption of B12 is dependent on its binding with intrinsic factor, a protein produced in the stomach and can be inhibited by the hydrogen cyanide and nitric oxide in cigarette smoke, nitrous oxide used for anaesthesia or recreational use and heating food in a microwave or cooker. Some medications, including Metformin (used for diabetes), anticonvulsants and proton pump inhibitors (PPIs), can also reduce absorption as can diseased or poorly functioning kidneys. If you are concerned, B12 levels can be checked by a doctor and any deficiency can be treated with supplements or a course of injections.


Symptoms of B12 deficiency include: extreme tiredness, lack of energy, pins and needles, muscle weakness, depression and cognitive problems such as impaired memory, understanding and judgement. It can lead to raised levels of the amino acid homocysteine, which can increase the risk of heart disease and stroke.

Pernicious anaemia

Pernicious anaemia is an autoimmune condition where the body’s defence system that protects against illness and infection attacks the body’s own cells that produce the intrinsic factor, necessary for B12 absorption. A B12 deficiency will ultimately develop but most cases can be easily treated with injections.

What’s the beef with B12 in meat?

B12 in meat is bound to animal protein which makes it harder to absorb. Our ability to absorb it declines with age due to loss of intrinsic factor and a drop in acid production in the stomach. Mild to moderate B12 deficiency is common in industrialised countries despite the fact that that a typical western, meaty diet provides around 5-7μg of B12 a day. Up to 40 per cent of older people in the UK suffer from low B12 because of impaired absorption and as most meat is consumed after cooking, there are further losses of B12. In the US, all adults over 50 are advised to get B12 from supplements or fortified foods because of the high incidence of reduced absorption from animal foods in this age group. Vegans have a heads-up as they routinely include both in their diet.

Cyanocobalamin versus methylcobalamin

There are two forms of B12 supplement:

Cyanocobalamin is a cheap and stable ‘inactive’ form of B12. It is used to fortify baby milk powder, breakfast cereals, vitamin drinks, soya milk and vegan meat replacements, as well as animal and fish feed. When taken orally, cyanocobalamin combines with intrinsic factor and is absorbed into the body. Tablets typically contain doses from as low as 2.5μg up to 1000μg.
Methylcobalamin is the ‘active’ form of vitamin B12 as it does not require intrinsic factors to be absorbed. It costs more and is not so stable which is why it is provided in higher doses from 500-2000μg and needs to be stored away from light.

US physician, author and internationally recognised speaker on public health issues, Dr Michael Greger says: “Unless you’re a smoker or have kidney failure, cyanocobalamin should be fine. That’s what I take!”

Is too much harmful?

B12 is water-soluble and excess amounts leave the body in urine. However, the NHS warns not to take too much as it could be harmful but 2,000μg a day is unlikely to cause any problems.

B12 basics

B12 is made by bacteria in soil and water. Traditionally, farmed animals got their B12 from eating food from the ground, which was taken up into their body cells and is how B12 ends up in meat and dairy products. Modern factory farming methods have changed the nature of farmed animal food and cattle and sheep now need B12 supplements too!

The B12 used in fortified foods and supplements (cyanocobalamin) is produced commercially by growing bacterial cultures in large vats. Some 80 per cent of global production is in France and over a half of it is used to supplement animal feed. This makes the recommendation to eat animal products to obtain B12 somewhat invalid. Cut out the middleman and get it straight from the source.

  Food (medium portions)   Vitamin B12 (μg)
Meridian Yeast Extract (4g serving – enough for one slice of toast) 2.8
Soya milk – Alpro Soya Original (200ml) 2.5
Marigold Engevita Yeast Flakes with added B12 (5g) 2.2
Koko long-life dairy free coconut drink (200ml) 0.8
Fortified breakfast cereal* (40g) 0.8
Alpro Simply Plain Yoghurt 0.6
Marmite (4g serving – enough for one slice of toast) 0.6
Vecon Vegetable Stock (1tsp/5g) 0.5
Pure Soya margarine (10g) 0.5
Alpro Heavenly Velvet Vanilla Dessert (125g pot) 0.3

The vitamin B12 content of selected foods

Note that some of the organic versions of these products are not fortified with B12.

*Many cereals fortified with B12 also contain vitamin D (D3) from lanolin, a substance obtained from sheep’s wool. At the time of writing, Tesco Malt Wheats, Sainsbury’s Wholegrain Malties, Waitrose Malted Wheats and Weetabix Oatibix Flakes all contain 2.1μg of B12 per 100g and no vitamin D, so are suitable for vegans.

You can achieve your 5μg of B12 a day by having either cereal with  soya milk, or yeast extract and toast for breakfast, soup with Vecon stock and a roll for lunch; for dinner, sprinkle a few yeast flakes on whatever you are having – pasta bake or spaghetti bolognaise – and a soya yoghurt or dessert for pudding. Of course, you need to ensure these foods are the fortified varieties! Topping up once or twice a week with a supplement is a good safety net to really ensure you’re getting enough. Plant foods, fermented soya foods and seaweeds do not provide a reliable source of B12.

B12 intake among vegans is increasing and many are routinely consuming B12-fortified foods and supplements and are therefore less likely to experience deficiencies due to age. So, a well-planned and varied vegan diet, including B12-fortified foods and supplements, not only meets our requirements but provides a healthier and safer source, setting us up for a healthy old age.

About the author
Dr. Justine Butler
I joined Viva! as a health campaigner in 2005 after graduating from Bristol University with a PhD in molecular biology. My scientific training helped me research and write numerous reports, guides and fact sheets for Viva! including Meat the Truth, Fish-Free for Life, One in Nine (breast cancer and diet) and the substantial report on the detrimental health effects of consuming dairy; White Lies. This accompanied Viva!’s report The Dark Side of Dairy which spelt out the inherent cruelty of dairy farming. We were the first UK group to take on the dairy industry in this way, and many of our supporters go vegan after reading these reports.

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