Vitamin B12 tablets are recommended to a lot of people, particularly those on a vegan diet are advised to take the supplements, in order to replace what is found almost exclusively in animal products. However, manufacturers appear to be taking advantage of this need with misleading packaging.

Vitamin B12 supplements are being sold in "extra strength" on websites like Amazon, as well as in many shops in parts of the world where veganism is popular.

However health experts say the vitamin amounts being offered in these effervescent tablets, capsules, lozenges and powders are an unhelpful excess that merely allows companies to increase their chances of their selling the product.

Adolescents and adults have an estimated daily requirement of between 1.5 and 4 micrograms of vitamin B12. Meanwhile many "extra strength" B12 supplements available online offer as much as 5,000 micrograms, with labels boasting more than 200,000% of the daily requirement.

Vitamin B12 is not believed to be toxic in high amounts, and yet there is no known benefit to exceeding recommending daily allowances of up to 25 micrograms.

According to researchers for Germany's consumer protection magazine Öko-Test, most of the 29 supplements they recently examined available on Europe's market exceed recommended values by far, some even being an "extreme" overdose.

With such supplements you are paying for nothing more than "expensive urine," the magazine's testers wrote.

Nevertheless, many manufacturers use "extra strength" labelling to market their products alongside claims like "supports brain cell function" and "helps reduce fatigue."

According to Öko-Test, some products contain animal ingredients, lactose, and gelatine. If you want to avoid them, check whether the supplement is labelled as vegan.

Before self-diagnosing a vitamin B12 deficiency, you should get a doctor's advice. If you eat a vegan or vegetarian diet, it is best to have your B12 levels checked once a year.

You are likely to need a vitamin B12 supplement if you have a vegan diet, as it is difficult to cover your needs with an entirely or predominantly plant-based diet.

Our body needs this nutrient for cell division and the function of the nervous system. A deficiency can lead to anaemia and nerve damage.

Sauerkraut and fermented soy contain small amounts of B12. But the really rich sources – meat, eggs, fish and dairy products – come from animals.