Episode 4: We Need to Talk About Vitamin B12

B12 might be the most under-discussed vitamin in medicine — and one of the easiest deficiencies to miss. In this episode, Dr Camilla Stokholm is joined by Dr Isobel Wilson, one of Mosaic Medical's founding doctors, to unpack why you can have a technically "normal" B12 blood level and still be genuinely deficient. They cover what B12 actually does in the body (red blood cells, nerve health, energy, DNA repair and neurotransmitter production), the difference between serum B12, active B12 and the MMA test, who's most at risk (plant-based diets, low stomach acid, PPIs, metformin, autoimmune gastritis, SIBO, and nitrous oxide exposure), and why the UK's reference range may be set lower than it should be. Camilla also shares her own story of discovering a genetic quirk affecting her B12 and folate levels, and how it connects to oestrogen clearance and breast cancer risk. Timestamps 00:00 Intro — why we need to talk about B12 01:36 What B12 does in the body 03:26 Classic symptoms: anaemia, fatigue, low mood, pins and needles 05:01 Why a "normal" B12 level can still mean deficiency 05:37 Serum B12 vs active B12 vs the MMA test 09:01 Nitrous oxide, occupational exposure and functional deficiency 12:56 UK vs international B12 reference ranges 15:24 Homocysteine, dementia and Alzheimer's prevention 16:09 Camilla's story: methylation, genetics and breast cancer risk 23:27 Other causes: diet, low stomach acid, medications 25:17 PPIs, metformin and autoimmune gastritis 28:19 SIBO and gut causes of B12 deficiency 30:14 Chronic fatigue, migraines and low mood 33:17 Best food sources — and when to consider B12 injections 41:02 Resources: the B12 Society and getting tested Think B12 might be part of your picture? Book a free discovery call with our team: https://mosaic-medical.com/ #FunctionalMedicine #VitaminB12 #B12Deficiency #RootCauseMedicine #Methylation #MosaicMedical