Detecting iodine deficiencies from dietary transitions using shopping data
Our examination of anonymised loyalty-card shopping records from Co-op Food, UK suggests that dietary transitions – such as replacing milk with alternative milk – could lead to nutritional deficiencies, notably iodine, which, if not addressed, may represent a significant public health concern, particularly in countries that do not mandate salt iodisation.
Duration: September 2022 - September 2023
Funder:
Future Food Beacon, UKRI
Partners:
Co-op Food
Key people:
Research summary
Plant-based product replacements are gaining popularity. However, the long-term health implications remain poorly understood, and available methods, though accurate, are expensive and burdensome, impeding the study of sufficiently large cohorts. To identify dietary transitions over time, we examine anonymised loyalty-card shopping records from Co-op Food, UK. We focus on 10,626 frequent customers who directly replaced milk with alternative milk. We then use product nutritional information to estimate weekly nutrient intake before and after the transition. 83% who converted to alternative milk saw a fall in iodine (44%), calcium (30%), and vitamin B12 (39%) consumption, with 57% reducing iodine purchase by more than 50%. The decline is even higher for those switching dairy and meat products.
Our findings suggest that dietary transitions – such as replacing milk with alternative milk – could lead to nutritional deficiencies, notably iodine, which, if not addressed, may represent a significant public health concern, particularly in countries that do not mandate salt iodisation.
Research findings
The study presented compelling evidence of iodine level reductions following dietary transitions. Individuals who replaced milk alone experienced a 44% decrease in mean iodine levels (from 345±229 μg/week to 194±166 μg/week), while those shifting from both milk and dairy to plant-based alternatives saw a substantial 63% decline (from 312±226 μg/week to 116±148 μg/week).
A group transitioning from milk and meat and poultry to plant-based options showed a 40% decrease (from 229±194 μg/week to 176±155 μg/week) despite continuing to consume other dairy products. The decline in iodine levels was not associated with a decrease in the number of items purchased per transaction, indicating that the reduction was due to a lack or insufficient presence of iodine in the plant-based products.
Additionally, maintaining a consistent diet, the baseline omnivore group exhibited higher iodine levels (mean: 680±445 μg/week), around 50% higher than the transitioning dietary groups, though still below the recommended intake levels.
The results for calcium, vitamin B12, and saturated fat also followed similar patterns, emphasising the impact of shifting from animal-based to plant-based diets on these nutritional elements.
These findings underscore the substantial implications of dietary shifts on iodine intake and other key nutrients among the analysed groups.
Further information
For more information please visit the N/LAB 'Detecting iodine deficiencies' project page.
