Méthodes d'étude de la consommation alimentaire chez les sportifs

In this paper, techniques generally used to assess dietary intakes of athletes — the daily (24-hr) recall, the diet history and the seven-day estimated food record — are critically reviewed. The measurement of the diet of individual has become a prime requisite of the nutritional sciences. Furthermore, recent statistical and technical developments resulted in its more widespread use. The task of analyzing dietary intake has been greatly simplified by computerized nutrient databases. However, as most nutrient analysis computer programs generate printouts that are impressive in appearance, the printouts may gain an unwarranted credibility and precision in the eyes of users.In the seven-day food record, the subjects are asked to weigh, describe and write down all items of food and drink eaten in one week. Records of food consumption can be made with estimated weights of food by measuring the quantity of food eaten using standard cups, teaspoons or tablespoons. It has been usual to ask subjects to keep records, weighed or estimated, for seven days, on the assumption that it is the shortest time necessary to take into account fluctuations in dietary patterns from weekdays to weekend. Since individuals vary markedly from day to day in their intake of foods and nutrients, more than seven days are required to obtain an accurate estimation of dietary energy and micronutrients intake. However food record should not be longer than seven days, since it is the longest time that a subject can be expected to cooperate. This day-to-day variability may adversely affect the statistical accuracy of estimates of intakes and thus it must be taken into consideration in the interpretation of results. Advantages of this technique are: accuracy since the quantity of food eaten or wasted can be weighed, estimation of food eaten does not rely on the subject's memory. Its drawbacks are: since subjects are asked to keep a record of everything they eat, they may alter their normal dietary habits, either to simplify the task, or to try to impress the investigators; its excessive burden on respondents.The daily (24-hr) recall is easier to perform than the seven-day food record but upon questioning subjects can be unable to remember the types and amounts of food the had consumed in the previous 24 hr. Some subjects overestimate their usual intake and some underestimate it. The 24-hr recall cannot accurately evaluate the dietary intake of individuals and it can only measure dietary intake of groups.The diet history uses questioning upon the food ordinarily consumed untill the food consumed is recorded in common household measures. The subject is asked for the frequency and usual size of portions using food models. The interview continues until a complete record has been made of the usual daily intake. The next step, known as the “cross check”, is used to clarify the information about the usual daily intake, by careful questioning about each food group.The choice between the diet recall and the diet record depends on many factors: the area of dietary investigation, the aim of dietary investigation, the number of individuals, etc.In the case of individuals, the aim is to evaluate the dietary intake of energy, macronutrients and micronutrients in order to evaluate if an athlete is at risk for inadequate nutrient intake. The Recommended Dietary Allowances (RDAs) are often used as the basis for determining whether nutrient intake is adequate. They are standards for nutrient intake designed to meet the nutrient needs of virtually all healthy individuals in our country. Therefore, most people who receive less than the RDA for a specific nutrient may nevertheless meet their own requirement. The diet record should be used to evaluate the dietary intake of athletes in as much as their degree of motivation is high. In the cases of groups, the 24-hr recall should be used although the seven-day food record should give a more accurate evaluation of dietary intake.It has to be concluded that the errors in all methods of dietary assessment are far greater than generally acknowledged. Accumulating evidence suggests that unbiased retrospective estimates of diet are unobtainable. Daily variation is the main factor determining the precision of recording methods of assessing dietary intake.