Vitamin B12 in Relation to Oxidative Stress: A Systematic Review

Abstract

The triage theory posits that modest micronutrient deficiencies may induce reallocation of nutrients to processes necessary for immediate survival at the expense of long-term health. Neglected processes could in time contribute to the onset of age-related diseases, in which oxidative stress is believed to be a major factor. Vitamin B12 (B12) appears to possess antioxidant properties. This review aims to summarise the potential antioxidant mechanisms of B12 and investigate B12 status in relation to oxidative stress markers. A systematic query-based search of PubMed was performed to identify eligible publications. The potential antioxidant properties of B12 include: (1) direct scavenging of reactive oxygen species (ROS), particularly superoxide; (2) indirect stimulation of ROS scavenging by preservation of glutathione; (3) modulation of cytokine and growth factor production to offer protection from immune response-induced oxidative stress; (4) reduction of homocysteine-induced oxidative stress; and (5) reduction of oxidative stress caused by advanced glycation end products. Some evidence appears to suggest that lower B12 status is related to increased pro-oxidant and decreased antioxidant status, both overall and for subclinically deficient individuals compared to those with normal B12 status. However, there is a lack of randomised controlled trials and prospective studies focusing specifically on the relation between B12 and oxidative stress in humans, resulting in a low strength of evidence. Further work is warranted.

Citicoline and Vitamin B12 Eye Drops in Type 1 Diabetes: Results of a 3-year Pilot Study Evaluating Morpho-Functional Retinal Changes

“…The effects of citicoline on RGC structure and function [21] are further supported by the role of the neurovascular unit at the level of the inner retinal layers in DR [22]. Studies indicate morpho-functional impairment of these layers in DR [21] and reduction in the levels of oxidative stress in neurogenerative processes by intake of vitamin B 12 [6]. We considered these findings as the rationale for designing a pilot study to assess the potential effects of citicoline and vitamin B 12 on the morpho-functional status of RGCs in patients with DM1.…”

“…Our study has some limitations. The patients with DM1 were treated with a combination of citicoline and vitamin B 12 , and the findings cannot be attributed to the properties of citicoline alone, since vitamin B 12 [6] may have affected the results. Vessel density of the superficial capillary plexus (SCP-VD) and foveal avascular zone (FAZ), and the deep capillary plexus (DCP-VD) (mean value ± standard deviation in micron) in patients with diabetes mellitus type 1 treated with citicoline and vitamin B 12 eye drops (DC group) or with placebo (DP Groups) at baseline and 12, 24, and 36 months of follow-up.…”

“…Studies have focused on DR as a microvascular disease [3]; nevertheless, some reports indicate that generation of the neural retinal elements, such as retinal ganglion cells (RGCs) and glial cells, was as an early event that could contribute to or worsen microcirculatory abnormalities [4,5]. Factors that can induce retinal neurodegeneration include an increase of excitoxic metabolites such as glutamate, branched chain amino acids, and homocysteine and decrease of folic acid and vitamin B 12 [6].…”

Protection from the Pathogenesis of Neurodegenerative Disorders, including Alzheimer’s Disease, Amyotrophic Lateral Sclerosis, Huntington’s Disease, and Parkinson’s Diseases, through the Mitigation of Reactive Oxygen Species

“…In addition, various B vitamins, including folate (or B 9 ), B 6 , and B 12 , have been reported to have a positive impact on AD patients in terms of their in luence on the metabolism of homocysteine, which is a sulfur amino acid source derived from the metabolism of methionine [88][89][90]. In addition, magnesium, ino sitol, choline, B 1 , iso lavones, and anthocyanins may help prevent the development of AD [91].…”

Dietary habits in Japanese patients with psoriasis and psoriatic arthritis: Low intake of meat in psoriasis and high intake of vitamin A in psoriatic arthritis

“…22 The effects of topical vitamin B 12 on psoriasis are also reported: it scavenges nitric oxides 23 and reactive oxygen species. 24 Several controlled and uncontrolled trials of systemic vitamin D or B 12 for psoriasis have been performed though the results are not conclusive. 19,21,25 The previous studies on dietary habits in psoriatic patients were mainly performed in Western countries.…”