Duplicate portion technique

Akesson, B. 1982. Content of phospholipids in human diets studied by the duplicate-portion technique. Br. J. Nutr. 47, 223-229. 

Macro element Intake Measured by the Duplicate Portion Technique and the Basket... 

Tab. 4.6 Macro element intake of adults with mixed diets determined by the duplicate portion technique and calculated by the basket method...

The calculation of trace element intake using the basket method led to a significant overestimation compared with direct analysis and the duplicate portion technique (Table 4.13). The overestimation is lowest in the case of copper and manganese (10-20%), medium for iodine, manganese and iron, and high for molybdenum, selenium. 

The calculation of inorganic food component intake using the basket method generally resulted in an overestimation of element consumption when compared with results obtained with the duplicate portion technique. The results ranged from 4% in the case of sodium to 44% for calcium and iron, 55% for selenium, 66% for chromium, and 240% for mercury and lithium. Hence, basket method should no longer be used to determine macro, trace and ultratrace element intake in humans. 

Schafer U, Anke M and Seifert M (2001) Manganese intake of adults with mixed and vegetarian diets and of breast-feeding and not breast-feeding women determined with the duplicate portion technique. In Ermidou S, and Pollet S, eds. 3 International Symposium on Trace Elements in Human New Perspectives, pp. 248 -262. Moro-giannis Achamai, Greece. 

Seieeet M and Anke M (2000) Alimentary lead intake of adults in Thuringia/Germany determined with the duplicate portion technique. Chemosphere 41 1037-1043. 

From 1988 until the end of the 20th century, the sodium intake in Germany was measured using a duplicate portion technique... 

Nursing mothers typically take in 15% more potassium than non-nursing women (Anke et al. 2003). At present, the normal daily potassium requirement of adults is not known, but for adults the minimum value has been cited as -1.6-2.0 g (Anonymous RDA 1989) or 2000 mg (Anonymous 2000). This requiremenf is an estimation, and is tantamount to a recommendation. A comparison of potassium intake measured by the duplicate portion technique and as calculated by the basket method showed an overestimation of calculated potassium intake by 30%. Hence, methods of potassium intake calculation should not be used (Anke etal. 2003). For example, Pittelkow (1992) calculated a daily potassium intake of 3.0 g kg for women and 4.0 g kg by men in Germany, but on average this was an overestimation by 25% for both groups. 

In Germany, the rubidium intake of adults with mixed diet was investigated in 10 populations using the duplicate portion technique (Table 1.4-4). 

Estimations of the average daily manganese intake of adults via a mixed diet in different countries ranged from 2.0 to 3.9 mg, when analyzed by means of the duplicate portion technique (Anke etal. 1999d,e Arnold etal. 2000 Bro etal. 1990 Ellen... 

The vanadium intake of women and men was systematically investigated by the duplicate portion technique in Germany and Mexico. Nineteen test populations aged 20 to 69 years collected duplicates of all consumed foodstuffs, sweets and beverages on seven consecutive days (Table 27.4). 

It has been suggested that conventional dietary assessment techniques, in conjunction with food tables, do not provide realistic estimates of micronutrient intakes and that accurate data on dietary intake of such nutrients can only be obtained by direct chemical analysis of foods or diets (Abdulla et aL, 1989 Bro et aL, 1990). There are three different methods of collecting data for direct chemical analysis (duplicate portion technique, aliquot samphng technique and equivalent composite technique) however, the most precise method of direct chemical analysis is the duplicate portion technique, as it directly measures actual nutrient intake (West and van Staveren, 1997). 

FFQs, as a direct semi-quantitative method of dietary assessment, are often easier to handle and can result in higher subject compliance, compared to weighed food records and the duplicate portion technique. However, the use of FFQs, as used in the study performed by Waldmann et al. (2003), may result in more sources of error in the estimation of iodine intake compared to other dietary assessment techniques, due to the choice of food portion... 

Two studies (Abdulla et al, 1981 Lightowler and Davies, 1998) used the duplicate portion technique to assess the iodine content of the vegans diets. Usual restraints and influences identified with this technique, such as the possible influence on dietary habits of collecting the food samples and gaining adequate cooperation from the subjects, might have been reduced in the Abdulla study that was undertaken in a controlled environment. These individuals consumed a modified diet to which they were unaccustomed, their iodine intakes would therefore not be a true reflection of their habitual diet. 

An increase in precision may be achieved by increasing the number of subjects, although more involved dietary assessment methods, such as the duplicate portion technique, are labor intensive and require a significant amount of subject commitment therefore, their use is usually restricted to small groups and data are collected over a short period of time (Petersen and Barraj, 1996). However, short time periods will miss any seasonal differences in the iodine content of foods that may occur. Seasonal variations were minimized in the Waldmann study, as 7-day FFQs were completed in both the autumn and spring seasons. 

Both studies highlight the difficulty of obtaining complete and representative duplicate diet collections for accurate assessment of iodine intake. Asking individuals to collect a duplicate diet does affect their dietary habits, and this must be taken into consideration in the assessment of iodine intake. Ways of alleviating the limitations of the duplication portion technique should be addressed, such as reimbursement for food and beverage costs of the duplicate diet collection. 

The validity of the duplicate portion technique may be problematic as the completeness of duplicate portions is often difficult to assess. However, the use of biochemical markers, such as plasma, serum and urine, may be incorporated into nutritional assessment studies to validate dietary surveys or confirm nutritional status. There are a number of different methods that can be used to assess iodine status and, in particular, for the determination of the severity of iodine deficiency. However, two main methods used for the assessment of iodine status are measurement of urinary iodine excretion and thyroid function tests (an indirect method of iodine sufficiency). 

Although the duplicate portion technique may be considered the best method for the assessment of trace element intake, it is not always practical to determine iodine intake using this method of dietary assessment. 

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