NQPlus - a longitudinal study on diet and health

Food Frequency Questionnaires (FFQ) are commonly applied to collect dietary
intake information. Ideally, an FFQ is generated using information on dietary
intake of a large representative sample. The Dutch FFQ tool now uses
information of the Dutch National Food Consumption Survey 1998, but this is not
only outdated, it also lacks sufficient information on the individual variation
of intake and food patterns. Also, objective information as obtained from
biochemical markers is needed to be able to evaluate the occurrence of under-
and overreporting.
Furthermore, the FFQ devoped by us for the LifeLines cohort of UMCG needs to be
valided.
Finally, the collection of longitudinal data on dietary intake and eating
behaviour in a large group of men and women provides the unique opportunity to
to study dietary intake, food patterns, and eating behaviour in relation to
relevant intermediate health outcomes, such as blood pressure, serum lipids,
obesity and cognition. This database will be used for several studies and PhD
projects of the division of Human Nutrition.

To set up NQplus, a longitudinal observational study on 1750 members of the
sampling frame to
a. build NDARD, the National Dietary Assessment Reference Database
b. build a database to validate the LifeLines FFQ
c. build a database and biobank for the study of diet, eating behavior and
intermediate health outcomes

In addition, three sub-studies are planned, each with an additional goal:
Sub-study 1 (additional study on energy intake and expenditure, i.e. double
portions,m doubly labeled water, and accelerometer) aims at retrieving more
detalied and valid information on a sub-samples of NQplus participants
regarding dietary intake (through double portion technique,) energy expenditure
and intake (doubly labelled water) and physical activity (with accelerometers);
Sub-study 2 (MRI and Fat biopsy) aims to study differences in phenotype between
subjects with similar BMI but different fat distibution over the body in a
sub-sample of NQplus participants;
Sub-study 3 (feces collection) aims at studying the variation in bacterial
microflora in the gut and relating this to aspects of dietary intake and health
(notably obesity).

Longitudinal observational study in three stages: the 1st stage consists of a
short questionnaire send out to 50,000 men and women aged 20-70 yrs of area
around Wageningen/Ede (EetMeetWeet, the Sampling Frame, not part of this
protocol);
persons willing to participate will be enrolled in NQplus (2nd stage, n=1750)
and they will be asked to fill in additional questionnaires on diet, lifestyle
and health, and to undergo a short physical examination incl. venapuncture.
When the 2nd stage starts, a specific number of participants will be invited to
participate in an additional sub-study (3rd stage).

Subjects will be asked for a physical examination three or five times in 48
months, incl. venipuncture and 24-hr urine collection. Half of the group will
fill in 13 web-based FFQs over 4 years. They have to collect their urine three
times and fill in five web-based dietary recalls. Participating in the second
group of 750 subjects means completing nine 24-hr dietary recalls, 3 by phone
and 6 web-based, over one year, and three in the last year of the study (1
phone, 2 web-based), and a total of 3 web-based FFQ*s over 4 years. All
subjects will be asked to fill in questionnaires on health, behavior and
personal characteristics. The questionnaires are clustered in such a way that
filling in takes maximally 40 minutes per month and overall max. 120 minutes
per year.
Venapunctures can occasionally cause a local hematoma or bruise and some
participants may report pain or discomfort.
Measurement of bone mass, fat mass and fat free mass will be done using DEXA.
This procedure uses a very low dose of X-ray, comparable to that of skiing or
walking half a day in the mountains.
Benefit for the individual participants is that they receive information on
their BMI, blood pressure, total and HDL-cholesterol, triglyceride and glucose
level, with interpretation based on the guidelines of Dutch GPs
(NHG-standaard), and the advice to contact their GP when values are to be
considered too high.

For the smaller sub-studies the burden includes possibly (when one decides to
participate) collection of double portions for 2 days (costs reimbursed),
wearing accelerometer for 7 days and for a small group the drink of doubly
labelled water and sampling of 4 spot-urines. Adverse effectsof doubly labelled
water have never been reported, they are naturally occuring stable isotopes.
For the sub-study on MRI one should be willing to do this, and also to give a
fat biopsy. Subjects with claustrophobia are excluded. A fat biopsy can
sometimes give a nasty bruise.
For the sub-study on gut microflora, subjects are asked to collect stool at
least once during one week (n=max 500).
Participation to the sub-studies is on voluntary basis.