Food Consumption Database Analysis Clinical Trial
Official title:
Examination of Varying Statistical Methods to Determine Meal Patterns Using Data From the National Adult Nutrition Survey (NANS) Ireland.
This study is a secondary analysis of the dietary, phenotypic and demographic data collected within the National Adult Nutrition Survey (NANS), Ireland, to determine meal patterns using a variety of statistical methods.
The study described here applies a variety of statistical methods to develop strategies to
determine meal based dietary patterns within nationally representative food consumption
databases. The work will apply methods such as Principal component analysis, latent class
analysis, basket set analysis, topic models and others to explore methods to accurately
identify meal based dietary patterns for use in personalised nutrition.
The work will initially focus on National Food Consumption Data collected within Ireland,
specifically using the National Adult Nutrition Survey (NANS), with details of data
collection fully outlined below.
Within NANS dietary, demographic and phenotypic data was collected from a Nationally
representative sample within Ireland from 2008-10. The fieldwork phase was carried out
between October 2008 and April 2010. Adults aged 18-90 years (740 males, 760 females) were
recruited in the Republic of Ireland. Eligible respondents were adults aged 18 years and over
who were free-living and who were not pregnant or breast feeding. A sample of adults was
randomly selected from a database of names and addresses held by Data Ireland (An Post). An
introductory letter and information leaflet were posted to each person selected from the
database. A researcher called to potential respondents‟ homes to introduce the survey and
invite participation. If the individual agreed to participate, a consent form was signed and
the survey commenced. If the person was not at home, the researcher called on three more
occasions on different days and at different times, before deeming them ineligible. For
groups that were not highly represented in the database, particularly 18-35 year olds, a
second level of recruitment was introduced. A second database of names and addresses was
compiled through referrals from respondents and participation was invited for those that were
contactable.
Food intake data collection - A four-day food diary was used to collect food and beverage
intake data. The researcher made three visits to the respondent during the four-day period: a
training visit to demonstrate how to keep the food diary and how to use the weighing scales;
a second visit 24-36 hours into the recording period to review the diary, check for
completeness and clarify details regarding specific food descriptors and quantities; and a
final visit one or two days after the recording period to check the last days and to collect
the diary. Respondents were asked to record detailed information regarding the amount and
types of all foods, beverages and nutritional supplements consumed over the recording period
and where applicable, the cooking methods used, brand names of the foods consumed and details
of recipes. Data were also collected on the time of each eating or drinking occasion, the
respondent's definition of each eating or drinking occasion (e.g. morning snack, lunch) and
the location of the preparation of the meal or snack consumed.
Food quantification and coding - A quantification protocol that had been established by the
IUNA (Irish Universities Nutrition Alliance) for the North/South Ireland Food Consumption
Survey (NSIFCS) (Harrington et al., 2001) was updated for the NANS. It is summarised as
follows: (1) Weighed by respondent/manufacturer weights) - A portable food scales (Tanita,
Japan) was given to each respondent. The researcher gave detailed instructions (including a
demonstration) as to how to use the food scales during the training session. This method was
use to quantify 46% of foods and drinks consumed. A further 10% of weights were derived from
manufacturer's weights. To facilitate collection of such data, researchers asked respondents
to collect all packaging of food and beverages consumed in a storage bag provided. (2) Food
Atlas - A photographic food atlas (Nelson et al., 1997) was used to quantify 16% of foods and
beverages consumed. (3) IUNA Weights - Average portion weights that had been ascertained for
certain foods by the IUNA survey team were used. This method was used to quantify 4% of foods
and beverages consumed. (4) Food Portion Sizes - "Food Portion Sizes" (Ministry of
Agriculture, Fisheries and Food, 1997) was used to quantify 11% of foods and beverages
consumed. (5) Household Measures - Measures such as teaspoon, tablespoon, pint etc. were used
to quantify 11% of foods and beverages consumed. (6) Estimated - Food quantities were defined
as estimated if the researcher made an estimate of the amount likely to have been consumed
based on their knowledge of the respondent's general eating habits as observed during the
recording period. This method was used to quantify 2% of foods and beverages consumed.
Nutrient composition of foods and estimation of nutrient intake - Food intake data were
analysed using WISP© (Tinuviel Software, Anglesey, UK). WISP© uses data from McCance and
Widdowson's The Composition of Foods, sixth (Food Standards Agency, 2002) and fifth (Holland
et al., 1995) editions plus all nine supplemental volumes (Holland et al., 1988; Holland et
al., 1989; Holland et al., 1991; Holland et al., 1992; Holland et al., 1993; Chan et al.,
1994; Chan et al., 1995; Chan et al., 1996; Holland et al., 1996) to generate nutrient intake
data. During the NANS, modifications were made to the food composition database to include
recipes of composite dishes, nutritional supplements, generic Irish foods that were commonly
consumed and new foods on the market. All previous modifications to the food composition
database were also checked and updated from current manufacturers‟ information as necessary.
The above modifications and additions comprise "The Irish Food Composition Database‟ (Black
et al., 2011).
Questionnaires - Four questionnaires were completed by the adults in the NANS. These
included: Health and Lifestyle Questionnaire: This questionnaire collected information on the
respondent's socio-demographics, education levels, attitudes to their own diet and weight,
sun exposure and supplement usage. Information on smoking status and alcohol intake was also
collected in this questionnaire. In the case of married/cohabiting couples, the higher social
class and education level was assigned to the respondent.
Physical Activity: Respondents completed a validated physical activity questionnaire (Epic
Physical Activity Questionnaire (EPAQ2)) (Wareham et al. 2002) to assess customary levels of
physical activity. The questionnaire consisted of three sections: activity at home, work and
recreation.
Food Choice Questionnaire: This questionnaire was designed to find out information on food
choice and the factors that can influence it, fear of eating new or unfamiliar foods and the
respondent's own opinion of their food preparation skills. Evaluation Questionnaire: The
researcher administered this questionnaire at the final visit to identify whether the
respondent's eating habits or physical activity patterns had been usual during the survey
week. Medication usage was also recorded here. Coded questionnaires were entered into the
customised Q-Builder software package (Tinuviel Software, Anglesey, UK). A dual data entry
method was used to enter questionnaires to ensure correct data entry.
Anthropometry - Anthropometric measurements were taken by the researcher in the respondents‟
homes. Weight, height, waist and hip circumference and measures of body composition were
recorded. Height was measured to the nearest 0.1cm using the Leicester portable height
measure (Chasmores Ltd, UK) with the respondent's head positioned in the Frankfurt Plane.
Waist circumference was measured in duplicate using a non-stretch tape measure and taken at
the naked site where possible. Waist circumference was measured at the midpoint to the
nearest 0.1cm between the iliac crest (top of hip) and the bottom of the rib cage (10th rib).
Hip circumference was measured in duplicate to the nearest 0.1cm using a non-stretch tape
measure. This measurement was taken over light clothing at the widest part of the buttocks at
the level of the greater trochanter (bony prominence of the thigh bone). Weight and body
composition were measured in duplicate using a Tanita body composition analyzer BC-420MA
(Tanita Ltd, GB) to the nearest 0.1kg. Respondents were weighed after having voided, wearing
light clothing and without shoes. Defining overweight and obesity in adults Body Mass Index
(BMI) was used to indirectly assess adiposity and was calculated as weight (kg) divided by
height squared (m2). The World Health Organisation (WHO) BMI cut-off points were used to
estimate levels of underweight (<18.5kg/m2), normal weight (18.5-24.9kg/m2), overweight
(25.0-29.9kg/m2) and obese (≥30 kg/m2).
Blood Pressure - Blood pressure was measured in triplicate from the right arm where possible,
leaving five minutes between each measurement. The measurement was taken with the respondent
sitting on a well-supported chair, with feet placed firmly on the floor. Prior to the
measurement, respondents were asked to sit quietly without talking or laughing for at least
five minutes. Respondents were asked to remove tight clothing from their upper arm and to
rest their arm such that the antecubital fossa (triangular cavity of the elbow joint) was at
the level of the heart, palm facing upwards. Measurements were taken in accordance with the
manufacturer's instructions for the OMRON M6 Comfort blood pressure monitor, with
fieldworkers having received training in taking the measurement prior to fieldwork.
Respondents were asked whether they had had anything to eat or drink (besides water) or
whether they had smoked in the 30 minutes prior to the measurement. This information was
recorded by the fieldworker. Respondents were informed of blood pressure readings that
consistently fell outside of the normal ranges and advised to visit their health nurse or
general practitioner for another reading.
Blood and Urine Collection and Analysis - Participants were asked to provide a blood sample,
fasting where possible, and a first void morning urine sample. The samples were collected by
a qualified nurse at designated centres within the survey area or in the respondent's home if
the respondent could not travel. In total, five tubes (45mls) of blood were collected from
respondents and where appropriate, inverted gently to ensure thorough mixing with
anti-coagulant. Of these, four were kept chilled and transported to the lab for further
processing and storage, while the fifth was kept at room temperature for full blood count
analysis. The blood tubes collected were: 3 x serum tubes (total 26ml); 2 x
ethylenediaminetetraacetic acid (EDTA) tubes (total 13ml); 1 x lithium heparin tube (6ml). A
50ml first void urine sample was also collected. Respondents were provided with a sterile
collection tube to collect the urine sample on the final survey visit. They were also
provided with an ice pack and asked to keep the sample chilled until they met with the nurse.
Samples were kept on ice during transport to the lab for further processing. A blood
collection form was completed in which the following was recorded: date and time of blood
collection, whether the respondent was fasting or not and any irregularities during blood
collection. Written consent to take a blood and urine sample was obtained along with consent
for the survey at the initial visit. Blood and urine samples were collected for the analysis
of a number of markers of nutritional status and metabolic health. In line with good ethical
practice, all samples were anonymised prior to analysis.
Physical activity and accelerometer - A triaxial accelerometer (Actigraph GT1M, ActiGraph,
LLC) was worn for the four days of the survey period. It was worn on the waist and reported
acceleration using a proprietary unit - "counts". An accelerometer diary was also used to
track activities that are poorly recorded by accelerometers such as cycling and swimming and
to record when the accelerometer was removed e.g. for sleeping/showering.
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