The Lifelines Diet Score¹⁾ is an instrument derived from the completed FFQ-heart filled in by adult Lifelines participants at the baseline assessment (1A Questionnaire 2)

The LLDS aims to measure diet quality. Based on literature available on associations between diet quality and socio-demographic characteristics, it was hypothesized that the LLDS should be higher in women, participants with higher educational level and in older individuals. These hypothesis were confirmed upon the application of the LLDS in 129.363adultLifelines participants with reliable FFQ data, which contributes to the construct validity of the LLDS. More detailed information regarding the development and application of the Lifelines Diet Score can be found in the European Journal of Clinical Nutrition: https://doi.org/10.1038/s41430-018-0205-z.Additionally, the validity of the LLDS depends on theLifelinesFFQ which it is based on. For information about the validity of the Lifelines FFQ, please see the FFQ Instrument Description Form. The reliability of the LLDS depends on the Lifelines FFQ which it is based on. For information about the reliability of the Lifelines FFQ, please see the FFQ Instrument Description Form.

The Lifelines Diet Score (LLDS) is a fully food-based and evidence-based tool to assess relative diet quality. Its highest scores represent diets expected to be most beneficial in light of the prevention of nutrition related chronic diseases. The LLDS is developed for use in scientific research, in which it can both be used as a primary determinant as well as for adjustment.

The LLDS is based on the 2015 Dutch Dietary Guidelines and underlying literature, and consists of 12 food groups for which there is consensus regarding their health effects. Nine food groups with positive (vegetables, fruit, whole grain products, legumes&nuts, fish, oils&soft margarines, unsweetened dairy, coffee and tea) and three food groups with negative health effects (red&processed meat, butter&hard margarines and sugar-sweetened beverages) are included in the score.In Lifelines, the LLDS can be calculated based in the baseline 110-item food frequency questionnaire (the heart of the flower-leaf FFQ). Per food group, the intake in grams per 1000 kcal iscategorized into quintiles, awarded 0 to 4 points (negative groups scored inversely) and summed.Moredetailed information regarding the development and application of the Lifelines Diet Score can be found in the European Journal of Clinical Nutrition: https://doi.org/10.1038/s41430-018-0205-z.

Dietary intake data is very difficultto work within scientific research, as it coversa great variety of aspects. The LLDS provides a simple tool to assign one score to an individual that reflects the overall quality of the diet. The LLDS is in line with the contemporary scientific evidence on associations between food products and chronic diseases. The LLDS can be used as a primary determinant in scientificresearch investigating the effects of diet quality. It can also be used for adjustmentin scientific research where diet quality, asan aspectof lifestyle behavior, is a potential confounding factor in the association that is beinginvestigated.

The LLDS is developed for use in the adult Lifelines population. An adapted version for usein children is available upon request.Please note:• The LLDS has been calculated for 129.363adult Lifelines participants for whom complete and reliable dietary intake data was available. This means that the pre-calculated LLDS variable provided represents diet quality compared to other individuals included in this group of 129.363participants. When preferred, one can also manually calculate the LLDS for a Lifelines sub-population of interest, to score relative diet quality within that sub-population. The syntax for calculation of the LLDS in a sub-population is available upon request.