What is the optimal B12 level in the UK?
                                
                                
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                                    4 min read                                
                            
                                According to recent NICE guidelines, a total B12 level below 180 ng/L is considered a confirmed deficiency, but a result between 180 and 350 ng/L is often inconclusive and requires clinical interpretation. Understanding the optimal B12 level in the UK is therefore not just about a single number, but a complex assessment of both blood markers and symptoms.