|  | For both surveys different versions of the NEVO table were used. As long as the differences in these versions reflects ‘real’ differences (the nutrient composition of foods really changed over the years), it would be safe to conclude that the fat intake of the Dutch population decreased by 13g/day. However, the differences could also be due to differences in analysis method (e.g. technical improvements, more accurate methods etc). If this is the case, you could no longer conclude that the change of 13g/day reflects real changes. NB. Analysis of these survey results revealed that after correction for artefacts in the nutrient database the real difference in fat intake between the first and second survey was 11g/day. (see Hulshof et al, Food Chemistry 1996; 57(1): 67-70) |  |

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The following examples illustrate why insight into the quality of the data in a FCDB is important.

Example 2: (clinical) dietary advice

Imagine the following situation: In the hospital, people with irritable bowel syndrome are advised to increase their intake of dietary fiber. The dietician uses food composition data to calculate the patients current fiber intake and also to select foods high in fiber to give a dietary advise. If the food table data are not very accurate, the dietary advise could be not as effective as it should be. In the worst-case, people are advised to eat the wrong foods or the advised amounts are not high enough to have a beneficial effect.

Example 3: Public health

Consider the following outcomes of the Dutch National Food Composition Survey (DNFCS):

- In 1987/1988 fat intake of the Dutch population was estimated to be 105 g/day, in 1992 the estimate was 92 g/day.

- To calculate these fat intakes, food composition data were used.

- For the first survey, the 1986/87 version of the Netherlands nutrient databank (NEVO) was used. In 1992 an updated version of this databank was used.

Comparison of the two versions of the NEVO table showed that for most products the reported fat contents was lower in the updated version than in the 1987/88 version. Do you think it is safe to concluded that the average fat intake of the Dutch population decreased with 13 g/day? Show answer.

So, in general terms, consequences of low quality data may lead to a wrong advice on the individual level, to a wrong evaluation of nutritional status at the population level and to disagreement among scientists at the research level. Therefore, in this module you will learn more about data quality issues focusing on analytical methods that are used to analyze foods.