The benefits of Vitamin B12 for nails?

Only assimilable through diet, vitamin B12 is one of the compounds that the body cannot do without. It is one of the eight B vitamins, a family that includes biotin and folic acid. First isolated in 1948 by Karl FOLKERS and his team from the bacterium Streptomyces griseus, vitamin B12 is essential for the normal functioning of the brain and the nervous and vascular systems. It is also used in cosmetics, mainly for its anti-inflammatory and antioxidant virtues, allowing to soothe and protect the skin and scalp. The interest for the nails of the vitamin B12 in topical application has not been studied to date. We can simply assume that due to its anti-radical properties, this molecule could potentially protect the nails from oxidative stress and prevent their splitting.

The oral intake of vitamin B12 is particularly beneficial for nail health. Indeed, several studies have shown that a deficiency in this molecule can affect the nails and alter their colouration. A lack of vitamin B12 in the body can result in entirely blue or brown nails or the presence of blue-black pigments on their surface with dark longitudinal streaks. A vitamin B12 deficiency is established when plasma levels are below 170-250 pg/mL. Another test that can detect a lack of vitamin B12 is the measurement of methylmalonic acid (MMA). If the MMA level is above 0.4 μmol/L, this indicates a deficiency.

By rebalancing the levels of vitamin B12, it is possible to restore the natural pigmentation of the nails.

In cases of deficiency, it has been demonstrated that oral intake and/or injections of vitamin B12 can restore the colour of nails. One study notably reports the case of a man presenting with generalised hyperpigmentation, including in his nails, due to pernicious anaemia, a disease caused by thebody's inability to properly absorb vitamin B12. Once the diagnosis was established, the patient was treated with intramuscular injections of vitamin B12 every day for seven days (100 mg/day). The injections were then reduced to twice a week for three weeks, then to once a month. The patient felt better within 24 hours and his haemoglobin level was normal after four weeks of treatment. However, his nails took a little longer to regain their natural pigmentation, which was restored after a few months.

Even without reaching the severity of pernicious anaemia, a deficiency in vitamin B12 can lead to weakened nails. To prevent this, the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) advises adults to consume at least 4 µg of vitamin B12 per day, a dose slightly increased for pregnant women. However, maintaining an adequate intake can prove challenging for vegetarians. Indeed, vitamin B12 is almost exclusively found in animal-derived products. The ones containing the most are presented in the following table. Nonetheless, a small amount of vitamin B12 can be found in cereals and wholemeal bread, as well as in certain plant-based milks (almond, soy, oat...). When this is not sufficient, a doctor may prescribe vitamin B12 supplements.