One of the most well-known challenges for vegans is getting enough vitamin B12, which is only found in animal products like eggs and meat. In fact low B12 is widespread in vegans - one British study found that half of the vegans in their sample were deficient.
Vitamin B12 deficiencies can lead to loss of energy, tingling, numbness, reduced sensitivity to pain or pressure, blurred vision, abnormal gait, sore tongue, poor memory, confusion, hallucinations and personality changes.
The symptoms of a deficiency will generally be reversed once adequate B12 levels are obtained. Ten micrograms of B12 spread over a day seems to supply as much as the body can use. If you do not have a dietary supply at all then deficiency symptoms usually take about five years or more to develop in adults, though some people experience problems within a year. The onset of symptoms will be more rapid in babies and children and they are also more vulnerable to permanent damage.
The two subgroups of vegans are at particular risk of B12 deficiency are long-term vegans who avoid common fortified foods (such as raw food vegans or macrobiotic vegans) and breastfed infants of vegan mothers whose own intake of B12 is low.
So, what foods could you include more of in your diet in order to up levels if you're a vegan?
Well the bottom line is that only fortified foods and B12 supplementation provide a reliable source of B12 if you're following a vegan diet. There are some claimed vegan friendly sources of B12 including human gut bacteria, spirulina, dried nori, barley grass and most other seaweeds but they have been shown through direct studies of vegans to be inadequate in supplying adequate amounts. Other purported 'rich' sources include tempeh, some varieties of mushrooms and marmite.
As reported by The Vegan Society, in many decades of vegan experimentation only B12 fortified foods and B12 supplements have proven themselves as reliable sources of B12, capable of supporting optimal health. It is very important that all vegans ensure they have an adequate intake of B12, from fortified foods or supplements. In fact, vegans using adequate amounts of fortified foods or B12 supplements are much less likely to suffer from B12 deficiency than the typical meat eater.
Other nutritional short falls to be aware of
Iron deficiency (one of the most common nutritional deficiencies) is another one that vegans are particularly prone to. This is because the form of iron that is most readily absorbed by the body is “haem iron”, which is only found in animal proteins. One German study found that 40% of the vegans they looked at were consuming less than the recommended daily amount.
Other common deficiencies among vegans include vitamin D3, omega-3, selenium, folate and iodine. While the body can make vitamin D3 through skin is exposure to sunshine, this doesn’t make up for the extra that vegans are missing from their diets. In the winter months, when the sun isn't as strong, omnivores living in the UK have nearly 40% more vitamin D3 in their blood than vegans.
Despite the issues touch on here, opting to follow a plant based diet is certainly not something that should be discouraged - it can form part of a healthy lifestyle as well as being a significant way to reduce a person's environmental impact on the planet. However the fact remains that there are several important nutrients that simply do not exist in plants or fungi. It is therefore about education - B12 deficiency amongst other nutritional gaps need never be a problem for well-informed vegans.