Comparison of Indices of Carbohydrate Quality and Food Sources of Dietary Fiber on Longitudinal Changes in Waist Circumference in the Framingham Offspring Cohort

The long-term impact of carbohydrate quality on abdominal weight gain is not fully understood. We aimed to examine the prospective relation of a carbohydrate quality index (CQI; defined by four criteria: dietary fiber, glycemic index, whole grain-to-total grain ratio, and solid-to-total carbohydrate ratio), total, cereal grain, vegetable, and fruit fiber, carbohydrate-to-total fiber ratio, and carbohydrate-to-cereal fiber ratio with changes in waist circumference (WC). Subjects were middle-aged to older, mostly white, participants in the Framingham Offspring cohort (n = 3101 subjects), with mean baseline age 54.9 +/- 0.2 years (mean +/- SE) and body mass index (BMI) 27.2 +/- 0.1 kg/m(2). Food frequency questionnaire (FFQ), health, and lifestyle data were collected approximately every four years over a median total follow-up of 18 years. Repeated measure mixed models were used to estimate adjusted mean change in WC per four-year interval across quartiles of carbohydrate variables. In the most adjusted model, a higher CQI was marginally associated with a smaller increase in WC (2.0 +/- 0.1 vs. 2.4 +/- 0.1 cm in highest vs. lowest quartile, p-trend = 0.04). Higher ratios of carbohydrate-to-fiber and carbohydrate-to-cereal fiber were associated with greater increases in WC per four-year interval (2.6 +/- 0.1 vs. 2.0 +/- 0.1 cm, p-trend < 0.001, and 2.5 +/- 0.1 vs. 2.1 +/- 0.1 cm in highest versus lowest categories, p-trend = 0.007, respectively); whereas higher intake of total fiber (1.8 +/- 0.1 vs. 2.7 +/- 0.1 cm, p-trend < 0.001), cereal fiber (2.0 +/- 0.1 vs. 2.5 +/- 0.1 cm, p-trend = 0.001), and fruit fiber (2.0 +/- 0.1 vs. 2.7 +/- 0.1 cm, p-trend < 0.001) were associated with smaller increases in WC compared to lower intakes. There was a significant interaction between total fiber and total carbohydrate (as % of total energy intake). After stratification, the association between fiber intake and change in WC was not maintained in the context of a high carbohydrate diet. Better carbohydrate quality, primarily higher fiber intake and lower carbohydrate-to-fiber ratios, may help attenuate increases in abdominal adiposity over time.

Automated summary

The study examined the long-term impact of carbohydrate quality on abdominal weight gain and found that a higher carbohydrate quality index was associated with smaller increases in waist circumference. Higher carbohydrate-to-fiber and carbohydrate-to-cereal fiber ratios were linked to greater waist circumference increases, whereas higher intakes of total, cereal, and fruit fiber were associated with smaller waist circumference gains. Better carbohydrate quality, characterized by higher fiber intake and lower carbohydrate-to-fiber ratios, may help attenuate increases in abdominal adiposity over time.