New survey finds lower levels of vitamin B12, riboflavin and iodine in UK milk A new survey of cows’ milk on sale in UK supermarkets has found that it contains lower levels of vitamin B12, riboflavin and iodine now compared to 1996. In the survey, vitamin B12 levels in milk were 50% lower on average compared to 1996. The UHT milk samples showed lower average levels of vitamin B12 compared to pasteurised milk in both the 1996 and 2023 analyses. Additionally, less than 10% of the adult population is currently considered vitamin B12 deficient, based on serum vitamin B12 levels as reported by the National Diet and Nutrition Survey. Iodine levels in milk were found to be 21% lower on average in 2023, compared to 1996 except for pasteurised skimmed milk.