Vegans intake assessment

Assessment of Iodine Intake and Iodine Status in Vegans... 

A number of investigations have studied the iodine intake of vegans (Table 45.3). The accuracy of the results from the five studies will ultimately depend on the dietary assessment employed. Two of these studies assessed iodine intake using the dupficate portion technique, while two estimated intake from food records, and the fifth study estimated iodine intake using a semi-quantitative food frequency questionnaire (FFQ). 

Table 45.3 Dally Iodine Intake in vegans using different dietary assessment methods (mean vaiues standard deviation) ...

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. 

Factors affecting the assessment of iodine intake in vegans... 

The findings from previous studies highlight the need to assess the iodine content of the vegan diet accurately. There are a number of factors that can influence the accurate assessment of iodine intake in vegans, including incomplete duplicate diet collections, the use of dietary supplements and the intake of dietary goitrogens. 

Dietary Supplements As dietary supplements are an important source of iodine in the vegan diet, the accurate assessment of iodine intake from this source is important. The use of dietary supplements by vegans is a crucial factor in determining their iodine intake and assessing whether supplement users could be at risk of excessive intakes of iodine. However, dietary supplements may be a confounding factor in the assessment of iodine intake, as there is uncertainty and variability in their iodine content (Lee et at, 1994). Furthermore, an excessive intake of iodine through some dietary supplements is not difficult because of their concentrated formulation and manufacmrers recommendations about the number of tablets to be taken, which may further exacerbate excessive intake. 

Previous studies assessing iodine intake in vegans have estimated intake from dietary supplements based on manufacturers declarations. Therefore, such intakes may be considered an approximation, as analysis has shown that the iodine content may differ from that stated on the packaging of the supplements and may also vary from tablet to tablet. 

Establishing links between acmal dietary iodine intake and iodine deficiency disorders relies on the availability of precise techniques to enable accurate estimation of nutritional intake. However, the evaluation of iodine intake is difficult, due to wide variations in the iodine content of food hence, obtaining an accurate assessment is not possible with food composition tables. This is particularly pertinent to vegans who consume a variety of unconventional foods not listed, or inconsistently listed, in such tables. 

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