Equivalent Glycemic Load and Insulinemic Responses Elicited by Low-Carbohydrate Foods: A Randomized Trial in Healthy...

The information on the Nutrition Facts Label may overestimate the available-carbohydrate (avCHO) content and glycemic impact of some low-carbohydrate foods containing novel carbohydrates.

The primary objective was to test the hypothesis that the glycemic impact of low-carbohydrate foods, quantified as equivalent-glycemic-load (EGL), measures their avCHO content accurately and precisely (within ±1g). The secondary objectives were to measure the glycemic and insulinemic responses elicited by 7 low-carbohydrate foods.

Healthy overnight-fasted adults (n = 25) consumed 20.8 g or 5.2 g avCHO from white bread (WB20.8, WB5.2, respectively), or 1 of 7 test-products in random order; each subject tested WB20.8 twice. Plasma-glucose responses were measured in all subjects with serum-insulin measured in 10. For each subject, 20.8 × T/W was calculated [T = incremental area under the glucose curve (iAUC) after the test-food, W = mean iAUC after WB20.8]; the mean of the resulting values (excluding outliers) was the test-food EGL.

The expected EGL of WB5.2 was 5.2 g and the measured value was 4.0 g (95% margin of error = 0.6 g). On the basis of the food-label, the test-products contained 3-12 g avCHO (total-carbohydrate minus dietary-fiber). However, because 5 of the test-products contained allulose, which is not included in dietary-fiber and not quantified on the food-label, their content of netCHO (avCHO minus allulose) ranged from 3 to 6 g; even so, their EGL values varied from just 0.6 to 2.4 g. The mean insulin responses elicited by the test-products were positively related to their protein content, but none differed significantly from that elicited by WB5.2.

The results support the hypothesis that the EGL measure is accurate and precise to within ∼±1 g. The EGLs of the 7 test-products were 20%-90% less than expected from their food-labels. The test-products elicited small insulin responses that were positively related to their protein content.This trial was registered at clinicaltrials.gov as NCT05870891 (https://clinicaltrials.gov/study/NCT05870891).