De betekenis van brood in de voeding en de faktoren die op het broodgebruik van invloed zijn

During the period after the Second World War the place of bread in the diet has gradually become less important. This is not only to impute to the decrease of the bread consumption itself, but also to other changes in the total food consumption. Based on the nutritional value of bread, most nutritionists adjudge a positive influence on the nutrient intake to an increased bread consumption. As bread is normally eaten in combination with other foodstuffs (as pastes, cheese and meats), it is important to know whether in practice the aimed effect can be actually expected from an increase of the (brown) bread consumption. It is also important for nutritional education activities to know which factors are of influence on the bread consumption (chapter 1). In this investigation attention has been paid to both of these aspects.

In chapter 2 the questions, relating to this subject, are described and formulated as follows:
- which factors have an influence upon the bread consumption and how do they affect each other at the completion of the bread consumption;
- what is the place of bread in the diet and what is the meaning of quantitative and qualitative changes of the bread consumption upon the nutrient intake?

In chapter 3 a description has been given of the development of the bread consumption after the Second World War. The average gross bread consumption in The Netherlands in 1951 still was 281 grams per person per day, in 1976 this only was 167 grams. As the amount of bread thrown away has increased over the years, the average net consumption of bread has decreased faster as suggested by the figures mentioned above. Till 1960 the average bread consumption has decreased without big changes in the mutual proportions of the four major categories of types of bread. After 1960, the average bread consumption decreased further and also the ratio between white bread and brown bread moved in favour of brown bread during this period. Both changes inside the breadsector and changes outside the breadsector can be mentioned as possible causes of the decrease of the bread consumption. In relation to the decreased bread consumption it has been stated that the so-called 'breadspecific' and 'non- breadspecific' factors have produced an increased interest in eating other foodstuffs than bread. The rise of the spending power has made it possible to translate this changed interest in a corresponding behaviour.

From literature data can be concluded that the bread consumption is connected with objective variables. Studying the literature resulted in the presumption that the bread consumption is also connected with subjective and situational variables.

For the benifit of detecting and making operational of the independent variables which could be connected with the bread consumption, a preliminary examination has been done. In this examination the family acted as researchunit (chapter 4). From this survey it appeared that the bread consumption behaviour is defined very individually. Therefore it has been decided to take the individual as research-unit in the proper investigation. This proper investigation has been done among employees. As the preliminary examination provided no useful information about relevant subjective variables, the proper investigation only includes objective and situational variables as independent variables. The situational variables can be subdivided in situational work variables and situational household variables.

Chapter 5 concerns a description of the bread consumption behaviour (on work- days) of 312 employees and the relationships between the breadconsumption behaviour and objective and situational work variables. The data have been obtained by means of written questionnaires. This way of collecting data has been discussed and compared with other data-collectingtechniques.

The bread consumption behaviour has been defined as the quantity and type of eaten bread and the frequency and the moments on which it is eaten. These four components of the bread consumption behaviour have been described and connected with each other. The average net bread consumption of this population is 6.6 slices a day. Brown bread is eaten by 47% of the respondents, white bread by 38% and 13% of the population consumes both types of bread. The average frequency with which bread is eaten is 2.6 times a day. The eating of bread is chiefly restricted to the period from breakfast up to and including lunch. There is no connection between the amount of bread eaten and the type of bread that is eaten. A positive correlation (r = 0.60) exists between the frequency with which bread is eaten and the amount of bread eaten. Lunch has the biggest participation in the total amount of bread eaten, followed by coffeebreak in the morning and breakfast. These three moments together represent 91 % of the whole quantity of eaten bread.

Breakfast has no discriminative value with respect to the amount of bread eaten. Differences in the bread consumption between the different categories of persons start to be outlined after breakfast.

Seven independent variables are statistical significantly connected with the amount of bread eaten. Three of them are objective variables, namely 'sex', ,occupation (social position)' and 'education'. The other four are the following situational work variables 'occupation (organisation of the labour)', 'going home during lunchtime', 'the place where lunch is used' and 'taking food from home to work'. However, the relationships mentioned above with 'education' and 'going home during lunchtime' prove to be spurious relationships. 'Occupation' is the most important single variable with respect to the amount of bread eaten; for the type of bread that is eaten this is 'education'.

By means of a multiple regression analyses it has been demonstrated that 31% of the variance of the amount of bread eaten can be explained by the objective variables and 9% by the situational work variables. The total amount of explained variance of the amount of bread eaten by the objective and situational work variables together is 34%.

In chapter 6 attention has been paid to the relationships between the bread consumption and situational household variables. The data are based upon a sample of 81 married male employees out of the 312. The data concerning the situational household variables have been obtained by interviewing the housewives. There are three situational household variables which are statistical significantly connected with the amount of bread eaten by the man, namely ,age of the housewife', 'net family-income' and 'stability of the bread buying behaviour'. It has been demonstrated that the situational household variables together explain 47% of the variance of the amount of bread eaten by the man.

The aggregate influence of the objective, the situational work variables and the situational household variables upon the bread consumption could only be investigated among 81 married male employees (chapter 7). These three types of independent variables together explain 73% of the variance of the amount of bread eaten. The explaining value of the situational household variables is greatest with 47%, followed by those of the objective variables (34%) and the situational work variables (24%).

From the interviews with the housewives some other aspects are recorded which can be distinguished from the use of bread and breadmeals (Appendix). These interviews give the impression that bread is to be considered as a foodstuff with a high purchase-frequency that is mainly bought in the morning. It is also to be considered as a foodstuff with a very slight price-sensitiveness. On the subject of bread there mostly are two 'gatekeepers' to distinguish; the housewife is the gatekeeper for the purchase and the individual is to consider as his own gatekeeper for the eating. In general bread is considered as a neccessary foodstuff to which a great value for health is adjudged.

With regard to the nutritional value of bread it rather is a well-known fact that bread supplies energy, vitamines, starch, fat and protein; less well-known is that bread supplies calcium and iron.

Breakfast (the first breadmeal of the day) is considered to be more important for health than the second breadmeal, but to both breadmeals a less signification hereabout is adjudged than to the hot meal.

On behalf of an orientation of the meaning of bread in the diet attention has been paid to the nutritional value of bread, to the bread consumption and to the total food consumption (chapter 8). There has been made use of gross food consumption figures of the Dutch population and of net food consumption figures of some categories out of that, namely schoolchildren, adolescents and employees. With these figures the place of bread in the diet has been described and the influence of quantitative and qualitative changes in the bread consumption has been investigated. It appears that bread is an important supplier of energy, protein, carbohydrate, iron, thiamine and dietary fibre. According as the contribution of bread in the diet is increasing, the nutrient intake is more favourable composed. Especially this applies to the energy-percentage supplied by fat, the energy- percentage supplied by carbohydrate and the supply of dietary fibre. Substitution of the total bread consumption by white bread should have an unfavourable influence on the supply of nutrients. On the contrary, substitution of the total bread consumption by brown bread should produce a favourable effect. Eating white or brown bread is especially affecting the supply of dietary fibre.

The main conclusion is, that an increasing bread consumption is desirable; preferably this has to be done in the form of brown bread. The results of this study lead to the statement that for measures stimulating the (brown) bread consumption it is preferable to make use of the relationships between the bread consumption and situational variables.