Dietary intake of adolescent and adult Lifelines participants was assessed with a food frequency questionnaire (FFQ) (section: nutrition).
The raw data from the heart FFQ at 1A were used to calculate nutritional sum scores.
Note that diet/food intake was also assessed in children aged 4-17 years and aged 8-12 years, as well as in newborns in the context of the birth cohort NEXT.

Dietary intake of adolescent and adult Lifelines participants was assessed with a food frequency questionnaire (FFQ) that was specifically developed for Lifelines to assess dietary risk factors for a considerable number of diseases. Since this resulted in a long and time-consuming questionnaire, the questionnaire was divided into four parts and called the Flower Food Frequency Questionnaire.
The questionnaire consists of one basic questionnaire, the heart of the flower, that covers energy and macronutrient intake and takes ~30 minutes to complete.
The other three shorter questionnaires, the petals, were only used in adults and cover the (micro)nutrients:

• FFQ1 (Petal 1) contains 59 food items and is used to estimate the intake of different types of fatty acids and caffeine
• FFQ2 (Petal 2) consists of 61 food items and is used to estimate the intake of vitamin B2, B6, B11, 12, calcium and soy.
• FFQ3 (Petal 3) consists of 64 food items and is used to estimate the intake of vitamin A, C, E, and dietary fiber. See Figure 1.

The Flower FFQ covers ≥96% of the absolute nutriënt intake and ≥93% of the between-person variability of each nutriënt as assessed in the Dutch National Food Consumption Survey from 1998. For each item participants indicated the frequency of consumption for the past month, this ranged from 'never' to '6-7 days per week'. Portion sizes were estimated using natural portions and commonly used household measures. Average daily nutriënt intakes were calculated by multiplying consumption frequency with portion size and nutriënt content per gram as indicated in the Dutch food composition table from 2006.

NB: The three FFQ petals were randomly distributed to adult participants during the follow-up questionnaires 1B, 1C and 2A Questionnaire 1, so that each participant received the petals in one of six possible orders ([1-2-3], [1-3-2], [2-1-3], [2-3-1], [3-1-2], or [3-2-1]).

For more information about the rationale for the flower FFQ see Brouwer-Brolsma et al. (2017)

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