Vegetarians, vegans and the elderly are at high risk of developing vitamin B12 deficiency through changes in their diets, according to a review of scientific studies published in the Journal of Agricultural and Food Chemistry.

Researchers from The United Graduate School of Agricultural Sciences of Tottori University and the Department of Nutrition of the Junior College of Tokyo in Japan reviewed nearly 100 scientific studies analyzing vitamin B12.

The study authors say the usual dietary sources of the vitamin are animal-based foods such as eggs, milk, meat and fish, but there are some plant-based foods which contain a high amount.

However, the scientists found that the only living things that can create vitamin B12 are particular bacteria, which live in the digestive tracts of animals. The bacteria can live on or near some types of plants, providing them with the vitamin.

But results of the study review showed that the human body is actually unable to use the plant-based form of vitamin B12, meaning that vegetarians and vegans are at high risk of developing a deficiency in this vitamin.

Additionally, elderly people who suffer from certain gastrointestinal disorders are at risk because their bodies are unable to absorb the normal type of B12 that is in food.

Vitamin B12 is vital for the formation of red blood cells, and B12 deficiency can lead to health problems such as pernicious anaemia – a type of blood disorder, as well as nerve and brain damage, which could eventually become irreversible. The vitamin also plays a vital part in helping the body absorb folic acid, facilitating the release of energy.

Previous studies have demonstrated the effects of vitamin B12 deficiency. For example, research from Rush University Medical Center revealed that elderly people with low B12 levels have a higher risk of developing brain shrinkage, leading to a loss of their cognitive skills.

Other research from Finland revealed that a low intake of B12 alongside the vitamin folate, could cause bouts of depression.

Interestingly, this most recent study review shows that although there are dietary supplements of B12 available in stores, such as Spirulina – a blue-green algae – and some shellfish, this actually contains a “false” form of vitamin B12 that the human body is unable to use.

In conclusion to the study review, the researchers recommend that vegans and vegetarians add vitamin B12 to their diet by eating fermented foods, particular types of mushroom that contain the vitamin and B12-enriched vegetables.

They recommend that the elderly should eat B12-fortified foods, fish or shellfish and canned clam broth.

In addition, they say that the heat to which vitamin B12 foods are exposed during storing and cooking can lead to the loss of the vitamin.