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.
Highlights
Vitamin B12 (B12), or cobalamin, is an essential water-soluble vitamin that is crucial in maintaining neuronal health and haematopoiesis [1]
B12-deficient patients showed increased tumour necrosis factor alpha and decreased epidermal growth factor levels compared to controls [41]. These results suggest that B12 might protect against inflammation-induced oxidative stress by modulating the expression of cytokines and growth factors [41]
This review aimed to investigate whether lower B12 status is related to increased oxidative stress
Summary
Vitamin B12 (B12), or cobalamin, is an essential water-soluble vitamin that is crucial in maintaining neuronal health and haematopoiesis [1]. The potential consequences of asymptomatic subclinical B12 deficiency, far, remain unclear. The triage theory posits that asymptomatic subclinical micronutrient deficiencies may induce reallocation of nutrients to processes necessary for immediate survival, at the expense of long-term health [2,3]. Over time, neglected processes could contribute to age-related disease development, in which oxidative stress is believed to be a major factor [4,5]. B12 may possess antioxidant properties [6], and subclinical B12 deficiency may contribute to oxidative stress and the onset of age-related diseases. We first discuss subclinical B12 deficiency, oxidative stress, and the potential antioxidant properties of B12. The subsequent systematic analysis aims to investigate whether lower B12 status is related to increased oxidative stress with specific focus on subclinical B12 deficiency
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