Alarmingly few young adults consume a diet that meets the recommended daily intakes for fruits, vegetables and saturated fatty acids. For the intake of total fat and trans fatty acids, the picture is a little more favourable. Lower levels of trans fatty acids specially in spreads and cooking fats compared to ten years ago have led to intake of trans fatty acids approaching on average the recommendation. Whether there are trends with regard to other nutrient factors cannot be stated because of the difference in survey methodology in earlier DNFCS’s.
The computerised 24 hour recall appears to be better in obtaining detailed information about food intake compared to the former food comsumption survey method. This is necessary in order to answer policy issues about exposure to potentially harmful substances. The telephone approach can implement independently repeated measurements reasonably efficiently. This allows the number of people to be estimated, for example, who normally meet the recommendations or who exceed the safety standards. The use of the 24 hour dietary recall also fits in with the international developments in nutrition monitoring. The switch from a sample of households to a sample of persons also fits with the individualisation of society. However, this approach has possibly also led to a low response rate.
In the future, it is desirable to determine whether the computerised 24 hour dietary recall method is suitable for all population groups and for other policy issues, and to search for a further increase in efficiency. Also, verification with the two-day written method is recommended to the benefit of trend studies and to search for response increasing strategies.
A sample selected from the consumer panels (n=1794) received a written questionnaire, information about the survey, and a request to participate in a follow-up survey. 50% of the respondents agreed to do so. Drop-out in the further phase of the survey was very small and it was not necessary to call up all the 900 respondents for the follow-up survey (2 x 24 hour dietary recall). A complete data set is available for 750 respondents. In respect of the 1794 invitations/requests sent, this represents a net response of 42%.
The 750 respondents to the DNFCS-Young adults were a good mirroring of the 19 to 30 year olds in the Netherlands with regard to age, region and education. Participants from areas of high population density were somewhat under-represented; the results were adjusted for this aspect.
Intake of fruit and vegetables and fat
Percentage of young adults that met the recommended amount of fruit, vegetables and fat
Fruit and vegetables.
- Only 2% of the survey group consumed 150g vegetables per day (150-200g is recommended daily intake).
- Less than 10% of the group consumed the recommended 200 g fruit per day.
Fat intake and energy.
- More than the half of the respondents consumed a diet with less than 35 energy% fat.
- 11% of the men and 6% of the women met the recommendation of diet with less than 10 energy% saturated fat.
- Almost 60% of the men and 28% of the women consumed a diet with less than 1 energy% trans fat.
|Fat, total (energy%)||34,4||26,9||41,7|
|Saturated fatty acids (energy%)||12,9||9,5||16,5|
|Transfatty acids (energy%)||1,06||0,70||1,49|
|Fat, total (energy%)||34,1||27,9||40,6|
|Saturated fatty acids (energy%)||12,5||9,2||16,2|
|Transfatty acids (energy%)||0,98||0,62||1,44|
|Fat, total (energy%)||34,6||26,2||42,6|
|Saturated fatty acids (energy%)||13,3||9,8||16,9|
|Transfatty acids (energy%)||1,13||0,81||1,50|
P5 = 5th percentile
P95 = 95th percentile
General written questionnaire
A general questionnaire (45Kb) (in Dutch) was sent to the persons selected by the market research agency, and also an invitation to participate in the follow-up study. The questions included a number of background and life style aspects, such as physical activity pattern, smoking, alcohol intake, educational level, family situation, and whether they had ever/never consumed certain foods or food groups.
A trained dietician interviewed each respondent twice by telephone on an unexpected day for the respondent about what they had eaten on the previous day (24 hour dietary recall).
Two independent days
The period between the first and the second interview was 8 to 13 days, and respondents were asked about their food intake on two different days of the week. The aim was to ensure that all days were equally represented.
24 hour dietary recall method
The 24 hour dietary recall covered the period from getting up in the morning until getting up on the following day (which was, in fact, the day of the interview). Food intake on Saturday was questioned on the following Monday.
The dieticians used computer controlled interview software (EPIC-Soft®, IARC) with which answers are directly entered in the computer.
The food consumption interviews with EPIC-Soft comprises the following steps:
- establish general information about the participant (such as birth date, height, weight) and the day of recall (special diet or eating habit; special day such as national holidays, holidays)
- for each consumption time: establish the time, the place and the main food products eaten;
- describe and quantify foods reported as eaten under b) above: when possible further specification is asked per food product, such as preparation method or the fat level;
- check the information on the quantities (warning when the limit value is exceeded) and missing information, and check on the basis of a general calculation of the intake of energy and macro-nutrients;
- establish the intake of vitamin and mineral supplements.
Food composition was based on the Dutch Food Composition Table 2001. Composition of dietary supplements was based on the Dutch Supplement Database, version 2003.
For correct evaluation of the food intake with regard to nutrition standards, not average intake over two days but the intake over a longer period (habitual intake) is important. The habitual intake was estimated from the reported intake.
The DNFCS-Young adults aimed to obtain data about the food consumption of men and women between the ages of 19 and 30 years and in particular, the consumption of fruits and vegetables and the amount of energy and the fatty acid profile of the diet.
DNFCS-Young adults was also implemented as a pilot for application of another survey technique than that used in food consumption surveys to date. There was a need for a new survey design because of changing policy requirements, socio-demographic developments, trends in food habits and developments with regard to research and survey methods. The new design was needed to obtain data on healthy nutrition and on food safety.
750 young adults
A representative sample was selected with regard to certain characteristics known to be related to food consumption: age (19-24 and 25-30 years), education, region and degree of urbanization.
Age 19 to 30 years
As a result of budget restrictions, the survey population was reduced to one age group. The choice of 19 to 30 years was made for reasons such as changes as well as stability in the diet in this life phase (group is no longer in the experimental phase) and also because of the potential that health improvements can be made when nutrition is redirected. In addition, the age group chosen is the same as used in the nutrition standards of the Health Council of the Netherlands and fits with the various campaigns directed to this age group.
Respondents in DNFCS-Young adults were drawn from representative consumer panels of the market research agency GfK. Persons in these panels take part in all types of surveys and are not selected on the basis of nutrition characteristics. Persons excluded from participation were institutionalised individuals, people who did not have sufficient command of the Dutch language, and pregnant and lactating women.
Organisation and implementation
Ministry of Health, Welfare and Sport
Report: RIVMNational Institute for Public Health and the Environment Centre for Nutrition and Health and TNO Quality of Life
Market Research Agency GfK