S100A8 and vitamin B12 deficiency: H. pylori infection and CagA-positive strains are linked to vitamin B12 deficiency and peripheral neuropathy via the promotion of atrophic gastritis, according to Lee et al., and Yang et al. recently demonstrated that H. pylori infection and CagA-positive strains are linked to vitamin B12 deficiency and peripheral neuropathy via the promotion of atrophic gastritis [91,92].