N° 64 | February 2012

Nutrition knowledge, healthy eating and dietary behavior

In Switzerland and other European countries, nutrition campaigns have been undertaken to increase population’s dietary quality (5-a-day campaign). Additional intervention programs have been also designed to improve nutrition knowledge and practice of particular target groups. The present study intended to assess the procedural nutrition knowledge of Swiss consumers.

Declarative knowledge versus procedural knowledge

In cognitive psychology, declarative knowledge is defined as knowledge about facts and things, whereas procedural knowledge is knowledge about the way in which actions are performed1. Therefore, procedural knowledge is closer to behavior than declarative knowledge. This distinction between declarative and procedural knowledge has also more recently been applied to the field of nutrition knowledge2,3.

Declarative knowledge Procedural knowledge
Fibre content of fruit How to compose a balanced menu
Number of calories in full fat milk How to choose a healthier option
between snacks

Procedural nutrition knowledge and Food Frequency Questionnaire

A random Swiss population sample (n= 1,043) received a written postal survey for both healthy nutrition knowledge and self-reported food consumption. The number of correctly answered knowledge items was correlated to food consumption frequencies.

Relations between procedural nutrition knowledge and dietary behavior

The consumers with higher procedural nutrition knowledge scores, consumed more vegetables, more fruit and more water than consumers with lower knowledge scores. Associations between demographic variables (e.g. gender, education) and nutrition knowledge replicate earlier findings4. We found a negative relationship between age and nutrition knowledge, indicating lower knowledge in older individuals. Moreover, higher knowledge was associated with females, higher education and nutrition-related qualifications. The consumers who reported following special diets prescribed by a doctor had significantly less procedural nutrition knowledge than the consumers who were not following such diets.

Misconceptions about healthy eating

The procedural nutrition knowledge items received between 53.3% and 91.8% correct answers, indicating that most consumers were well informed about how to follow a healthy eating pattern. However, for a substantial share of the items every third to fifth participant was unable to answer correctly. We found that 35% of consumers believed that, for a healthy diet, dairy products should be consumed in the same amounts as fruit and vegetables, whereas 19% of consumers believed that a healthy meal should consist of half meat and one quarter vegetables and side dishes. Just under one third (28%) of consumers considered that a balanced diet implied eating all foods in the same amounts, and over 17% of consumers considered that eating a diet with a high proportion of fruit and vegetables was as unbalanced as eating a diet high in fat. Many consumers (38%) agreed that to eat healthily, less fat, but not necessarily more fruit and vegetables, should be eaten.

This study highlights the fact that the food pyramid is not present in many consumers’ minds and that it is not taken into account in daily food choices. According to the food pyramid, fruit and vegetables should constitute the largest part of our diet (five servings) after fluids, dairy should be consumed in smaller amounts (three servings), and meat should play an even more minor role (one serving)5. Almost 12% of respondents believed that eating healthily meant eating less, no matter which food are reduced. The literature, however, suggests that the way to maintain a zero energy balance is not primarily by eating less, but by lowering the energy density of the diet6. This can be accomplished by increasing the consumption of foods such as water-rich vegetables, fruit and cooked whole grains. Older respondents might be less familiar with the food pyramid. This might be because many of our items were based on the food pyramid, which only appeared in 1998 in Switzerland5.

Moreover, the respondents appeared to have difficulty interpreting the term ‘balanced diet’. In the literature, this is defined as a diet that contains the “essential nutrients in appropriate quantities required for growth or the maintenance of health approximately each day or over a period of week”7. In practice, a balanced diet is one which is low in saturated and trans fats, cholesterol, added sugars, salt and alcohol and high in fruits and vegetables.

Poor procedural knowledge was observed in those consumers who considered that a healthy diet was equivalent to consuming vitamins. Focusing only on the consumption of vitamins is an oversimplification of the healthy nutrition concept. Some consumers considered that fruit could be replaced entirely by fruit juice or tablets. The WHO treats fruit and vegetables as a food category rather than referring to their nutrients, because the benefits of fruits and vegetables cannot be ascribed to one or several particular nutrients8.

Conclusions

Many consumers appear to be unfamiliar with the practical implications of the food pyramid, the concept of a balanced diet and the importance of increasing fruit and vegetable consumption. Particularly older individuals and those following medically prescribed diets could profit from more education on how to compose a healthy diet. The challenge will be to find the right settings and effective ways to communicate nutrition messages to consumers.

  1. Anderson, J.R. (1995) Cognitive Psychology and its Implications, 4th edn. New York, NY: WH Freeman and Company.
  2. Miller, C.K. & Achterberg, C.L. (2000) Reliability and validity of a nutrition and food-label knowledge test for women with type 2 diabetes mellitus. J. Nutr. Educ. 32, 43–48.
  3. Worsley, A. (2002) Nutrition knowledge and food consumption: can nutrition knowledge change food behaviour? Asia Pac. J. Clin. Nutr. 11, S579–S585.
  4. Parmenter, K., Waller, J. & Wardle, J. (2000) Demographic variation in nutrition knowledge in England. Health Educ. Res. 15, 163–174.
  5. Walter, P., Infanger, E. & Mu¨hlemann, P. (2007) Food Pyramid of the Swiss Society for Nutrition. Ann. Nutr. Metab. 51(Suppl. 2), 15–20.
  6. Rolls, B.J., Drewnowski, A. & Ledikwe, J.H. (2005) Changing the energy density of the diet as a strategy for weight management. J. Am. Diet. Assoc. 105, S98–S103. Anderson, J.J.B. (2005) Nutrition and Health: An Introduction. Durham, NC: Carolina Academic Press.
  7. World Health Organization (2003) Diet, Nutrition and the Prevention of Chronic Diseases. Report of a Joint WHO/FAO Expert Consultation. Available at http://www.fao.org/DOCREP/005/AC911E/AC911E00.HTM (accessed on 7 July 2009).
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