====== Lifelines Diet Score ======

The Lifelines Diet Score((Vinke PC, Corpeleijn E, Dekker LH, Jacobs Jr DR, Navis G, Kromhout D. Development of thefood-basedLifelines Diet Score (LLDS) and its application in 129,369 Lifelines participants. European Journal of Clinical Nutrition. 2018.Aug;72(8):1111-1119)) is a [[diet scores|diet score]] derived from the completed [[FFQ|FFQ-heart]] filled in by ~130.000 adult [[cohort|Lifelines]] participants at the [[1A|baseline]] assessment ([[1A Questionnaire 2]]) ([[sections|section]]: [[Nutrition]] ([[Diet scores]]) and [[secondary & linked variables]]).\\ 
The LLDS was developed by the UMCG [[https://www.rug.nl/research/epidemiology/?lang=en|department of epidemiology]] and 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. On the Lifelines data, the [[Dutch Healthy Diet index]] has been developed as well, which is a tool to assess a participant's own diet quality and adherence to the 2015 Dutch dietary guidelines.

The LLDS can be requested in the [[https://data-catalogue.lifelines.nl/|Lifelines catalogue]]. When this data has been used in your research, you will have to include a reference to the the following paper:
  * [[https://doi.org/10.1038/s41430-018-0205-z|Vinke, P. C., Corpeleijn, E., Dekker, L. H., Jacobs, D. R., Navis, G., & Kromhout, D. (2018). Development of the food-based Lifelines Diet Score (LLDS) and its application in 129,369 Lifelines participants. European Journal of Clinical Nutrition, 72(8), 1111-1119.]]
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===== Use of the LLDS =====

Dietary intake data is very difficult to work with in scientific research, as it covers a 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 scientific research investigating the effects of diet quality. It can also be used for adjustment in scientific research where diet quality, as an aspect of lifestyle behavior, is a potential confounding factor in the association that is being investigated.\\
The LLDS is developed for use in the adult Lifelines population. An adapted version for use in [[children]] is available upon request.\\ 
**Please note:** The LLDS has been calculated for ~130.000 adult 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 participants. 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.

===== Background =====

The LLDS is based on the [[https://www.healthcouncil.nl/documents/advisory-reports/2015/11/04/dutch-dietary-guidelines-2015|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 health effects
  - 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
  - sugar-sweetened beverages
The LLDS was calculated based on the baseline 110-item food frequency questionnaire (the heart of the flower-leaf FFQ). Per food group, the intake in grams per 1000 kcal is categorized into quintiles, awarded 0 to 4 points (negative groups scored inversely) and summed. More detailed information regarding the development and application of the LLDS can be found in the paper referenced below. 

===== Validity & Reliability =====

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 129.363 adult Lifelines participants with reliable FFQ data, which contributes to the construct validity of the LLDS. 
Additionally, the validity &reliability of the LLDS depends on the Lifelines [[FFQ]] which it is based on.