Vitamin B12

How much do you need daily?

The UK recommended intake is 1.5 micrograms of vitamin B12 per day. In the US it is slightly higher at 2.4 micrograms. In 2015, the European Food Safety Authority set a new ‘adequate intake’ of 4.0 micrograms per day. Viva! Health recommends aiming for an intake of around 5.0 micrograms per day from fortified foods with the regular use of supplements to ensure topping this up.

Note: A microgram is a millionth of a gram. So we only need a tiny amount of B12 – but getting that small amount is vital.

Are we getting enough?

The 2016 National Diet and Nutrition Survey found evidence of low vitamin B12 status in girls aged 11 to 18 years and in adults aged 19 years and over. Three per cent of girls (11 to 18 years), six per cent of adults (19 to 64 years), five per cent of men (over 65) and eight per cent of women (over 65) had vitamin B12 blood levels indicating deficiency. Low levels are not uncommon, especially in people over 50.

 A number of studies suggest that vegans are lacking in vitamin B12, but by their own admission, many of these studies only measure dietary intake and fail to account for intakes from supplements. 

Why do we need it?

All B vitamins help the body produce energy from food. Vitamin B12 also helps maintain healthy nerve cells and helps in the production of DNA, the body’s genetic material. Vitamin B12 works closely with folic acid, to make red blood cells, to help iron work better in the body and to produce a compound involved in immune function and mood.

B12 is made by bacteria in soil and water and to some extent bacteria in the gut (although production in the gut occurs in a different area to where absorption takes place). Traditionally, people, as well as farmed animals, got B12 from eating food from the ground because B12 is made by the bacteria in the soil. However, now food production systems are so sanitised, we need to take a supplement. Animal products contain vitamin B12 because the animals are given this vitamin in their feed too. Around 80 per cent of global production of B12 is in France and over a half of that 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.  

Whether you choose fortified foods or supplements, you need to consume these regularly. There’s no need to take extra high doses but if you do have a high-dose supplement, taking up to 2,000 micrograms a day of vitamin B12 is unlikely to cause any harm.

There are a number of different forms of B12 – the main two are cyanocobalamin and methylcobalamin. Cyanocobalamin is a cheap and stable form of B12 used in most enriched foods and supplements – as long as you’re healthy, it’s perfectly suitable. Methylcobalamin is an ‘active’ form of vitamin B12. It costs more as it is not so stable and is recommended for smokers and people with kidney problems.

Absorption of B12 is dependent on its binding with intrinsic factor, a protein produced in the stomach. Absorption can be reduced by a number of factors: poor functioning kidneys; the diabetes drug Metformin and proton pump inhibitors (PPIs); nitric oxide in cigarette smoke and nitrous oxide (laughing gas) used for anaesthesia.

If you heat B12-fortified plant-based milks, some of the B12 might be lost – it depends how long you're heating it for and at what temperature. In a microwave, B12 can get destroyed in a couple of minutes but if heating on the hob or steaming it, the milk would have to be at or near boiling temperature for five to seven minutes to destroy a significant amount of B12. So a traditional approach is better!

Do I need a supplement?

Yes, especially if you’re over 50. The human body is less efficient in absorbing vitamin B12 with age so it’s important to take a supplement – this is recommended for everyone, regardless of diet.

Erring on the side of caution, Viva! Health recommends an intake of 5.0 micrograms per day from fortified foods with the regular use  of supplements to ensure topping this up. This is particularly important for children too.

The best plant sources

The best plant sources of vitamin B12 include yeast extract (Marmite/Vegemite), nutritional yeast flakes with B12, B12-fortified plant-based milks, B12-fortified plant-based yoghurts and desserts, B12-fortified breakfast cereals and B12-fortified margarine. Make sure the ones you buy are fortified with B12.

Signs of deficiency

Extreme tiredness, lack of energy, pins and needles sensation, muscle weakness, depression and cognitive problems such as impaired memory, understanding and judgement.

A lack of B12 can lead to a raised level of the amino acid homocysteine in the blood which has been linked to heart disease.

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.