Development and validation of a dietary assessment tool to determine dietary intake of people living in oesophageal cancer risk areas in the rural Eastern Cape of South Africa

TL;DR: A cross sectional study to determine the dietary intake of the people living in the Eastern Cape of South Africa showed a higher that recommended fumonisin intake per person as well as nutrient deficiencies associated with a risk of developing OC.

Abstract: Rural areas in the Eastern Cape (EC) Province of South Africa have a high incidence of oesophageal cancer (OC). Amongst the known risk factors associated with the cancer is fumonisin exposure (a mycotoxin growing on maize), poor dietary habits and nutrient deficiencies. Little is known about the current dietary habits and nutrient intake of these people, and therefore maize consumption and fumonisins exposure. Because of large cultural differences a novel dietary assessment tool had to be developed. The dietary assessment tool was developed with interviews, focus groups and dishing up sessions. The tool comprises a quantitative food frequency questionnaire (QFFQ) and a set of food photographs (portion sizes and ratios). Although the validity of the photographs was tested, results indicated that the photographs mostly had poor validity and general over-reported, especially the large portion. This however, provided valuable information regarding the size and direction of the incorporated errors. The tool was further validated by comparing it with four 24-hour recalls energy expenditure (EE), blood and urinary biomarkers. Results indicated that the assessment method was valid for all food groups except bread and beverages and was therefore valid to measure fumonisin exposure. Furthermore, results indicated that the tool was only partially able to measure nutrient intake. The tool compared poorly with EE measured with a physical activity questionnaire, as well as with Schofield’s EE equations. The use of urinary biomarkers was not very successful as very few complete samples were collected. The assessment method had also poor validity results when compared against blood biomarkers. Reliability was determined with a test-retest method and it was concluded that the tool was reliable when measuring dietary intake but is only partially capable of measuring nutrient intake. A cross sectional study was conducted to determine the dietary intake of the people living in this area. Results showed a higher that recommended fumonisin intake per person as well as nutrient deficiencies associated with a risk of developing OC. Also, a low consumption of fruit has been identified. Many of the dietary risk factors identified in the area are modifiable and appropriate prevention campaigns should be implemented by the appropriate health authorities. Un ive rsi ty of Ca pe To wn iv To my beloved ...... Without you I am but a shell.