Comparison of fermentable carbohydrate consumption in plant-based vs western-style diet groups

Background: Fermentable carbohydrates (FC) improve health, but data are lacking on their presence and relationships with dietary quality in self-selected diets. Types of foods chosen within different dietary patterns may vary, which could impact the FC distribution and overall diet quality, but these relationships have not been examined to date. Objective: This cross-sectional study compared intakes of FC and subclasses [soluble dietary fibers (SDF) and polyols] and diet quality in plant-based (PB) and western-style (WS) diets. Methods: Dietary data were collected from 84 adults (26.8 + 11.5y; 23.0 kg/m(2)) through diet history questionnaire-III; dietary quality was assessed by the 2015 Healthy Eating Index (HEI-2015). Independent sample t-tests compared FC and subclasses (in grams and g/1000 kcal) in PB and WS diets. Multiple regression analyzed HEI-2015 of PB and WS adjusting for confounders. Analysis of variance evaluated if diet influences relationships between diet group and FC and subclasses intakes. Results: The average intakes of FC [PB (9.8 +/- 5.2g); WS (7.3 +/- 3.6g), p = 0.014*], SDF [8.3 +/- 4.4g; 6.4 +/- 3.1g, p = 0.02] and polyols [1.5 +/- 1.0g; 1.0 +/- 0.6g, p = 0.008] were higher in PB than WS. Similarly, the average intake of FC (gram/1000 kcal) [6.5 +/- 5.9 vs 4.6 +/- 3.9, p = 0.0001*], SDF (g/1000 kcal) [4.5 +/- 2.0vs 4.0 +/- 1.6, p = 0.0003*] and polyol (g/1000 kcal) [1.0 +/- 0.6 vs 0.6 +/- 0.3, p = 0.0006*] was significantly higher in PB than WS. The mean HEI-2015 score for PB was higher than WS [77.9 +/- 9.1; 64.7 +/- 11.4, p < 0.0001, adj. R-2 = 0.36]. Higher FC (10.7 +/- 3.6g; 5.5 +/- 2.4g, p = 0.001*), SDF (9.0 +/- 3.0g; 4.8 +/- 2.2g, p = 0.001*), and polyols (1.7 +/- 0.9g; 0.7 +/- 0.3g, p = 0.001*) were seen in the high diet quality PB group than low diet quality WS group. Conclusion: Overall, self-selected PB diets showed higher FCs and subclasses, and HEI-2015, than WS diets. Importantly higher-quality diets, either PB or WS, had higher FCs and subclasses in this population. An understanding of these relationships might help articulate strategies to increase FC intake.