The GUTFIT Cohort: Identifying Dietary Intake of Chinese New Zealanders with Functional Constipation - A Case-Control Study

Abstract

Background: The aetiology of functional constipation (FC) is poorly understood; however, it is believed that an individual's genetics, environment, and lifestyle behaviours all contribute to FC manifestation. Hence, populations originating from different geographical regions likely experience different drivers of FC, including diet, yet drivers in Asian compared to Caucasian populations are under-researched. This study aimed to investigate whether the diets of Chinese with FC (Ch-FC) differ from non-Chinese with FC (NCh-FC), alongside Chinese and non-Chinese healthy controls (Ch-CON and NCh-CON respectively). Methods: A cross-sectional observational case-control study with a longitudinal subgroup was conducted to investigate dietary differences in Ch-FC (n = 11) compared to controls (NCh-FC, n = 16; Ch-CON, n = 19; NCh-CON, n = 20). Three-day food diaries (3-DFDs) and a food frequency questionnaire (FFQ) were used to collect short-term and habitual nutrient intakes, respectively. The time-dependency of nutrient intakes was assessed using 3-DFDs at three additional time points over three months in a subgroup of the participants (n = 47). The FFQ also measured food intake, used to identify dietary patterns (DPs) with principal component analysis. Dietary intake and adherence to DPs were compared across cases and controls. Results: Dietary intake of individuals with FC did not differ by ethnicity (ethnicity x FC status interaction p>0.05). Although differences in habitual nutrient intake were not identified, the 3-DFD found that individuals with FC consistently consumed less fibre and several micronutrients, including magnesium, compared to healthy controls (FC status effect p<0.05). Chinese individuals consistently consumed more cholesterol and less alcohol compared to non-Chinese (ethnicity effect p<0.05). The intake of several nutrients depended on assessment time point. Those with FC consumed 5.5 fewer servings/week of fruit than healthy controls (FC status effect p<0.05), while Chinese individuals consumed 1.1 fewer servings/week of fast food than non-Chinese (ethnicity effect p<0.05). Three DPs were identified: Discretionary (positive loadings for fast food, sugar/sweets/baked goods, processed meat, alcohol), Guideline (positive loadings for meat, starches, vegetables, wholegrains), and ‘Mixed’ (positive loadings for processed meat, oils/spreads, fruit, vegetables, coffee/tea). DP adherence did not differ by ethnicity or FC status (p>0.05). Conclusions: Diet did not differ between Ch-FC and NCh-FC, suggesting environmental influences may have had a larger impact on diet compared to ethnicity. Fibre, magnesium, and fruit may be plausible dietary targets for FC. Alternative and more targeted definitions of dietary intake, such as investigating specific foods and defining food groups more narrowly, are required to further understand ethnic differences in the diets of Chinese and non-Chinese individuals with FC.