Participant flow chart
This study was conducted during September- December, 2020. Figure.1 shows Consolidated Standards of Reporting Trials (CONSORT) diagram. Thirty-three volunteers were recruited to the study. After screened, fifteen subjects were excluded. Eighteen participants including nine males and nine females (22 – 48 years) were randomly assigned into three groups. All participants completed all tests; thus, the data was intention-to-treat analyzed from all randomized participants.
As shown in Table S1 (Supplemental material), all average baseline laboratory parameters, except for total cholesterol, were in normal range. Although the mean of total cholesterol was higher than the normal range, the means of total cholesterol to HDL-C ratios were normal (less than 5.0 for male and less than 4.5 for female ). Table 3 shows no statistically significant differences in age, BMI and laboratory characteristics among the randomized groups (p-value ≥ 0.05).
Postprandial glucose response
Figure 2a shows no significant difference of fasting plasma glucose levels among all test days. After consuming the complete nutrition drink, the postprandial glucose concentrations were rapidly risen and peaked at 20 min. In contrast, those of glucose solution and white bread reached maximum levels at 35 and 50 min, respectively (Figure 2b). While the plasma glucose levels of complete nutrition drink were declined first, those of glucose solution and white bread continuously remained high. Table 4 shows that the average AUCi of glucose response for complete nutrition drink (mean ± SE: 1,574 ± 378.0, 95% CI: 833.5, 2420) was significantly lower than those of glucose solution (p = 0.0026, mean ± SE: 3,612 ± 577.9, 95% CI: 2393, 4831) and white bread (p= 0.0001; mean ± SE: 2,974±448.6, 95% CI: 2028, 3921). The effect size was 7.04 and 7.11 for comparison with glucose solution and white bread, respectively. The average GI of complete nutrition drink were 48.2 ± 10.4 when using glucose solution as reference food, which was not statistically different from the GI calculated when using white bread as the reference food (46.7 ± 12.7; p > 0.99).
Postprandial insulin response
Figure 2c shows that after consuming complete nutrition drink the postprandial insulin concentrations were risen and peaked at 50 min, while the highest peak for glucose solution and white bread were at 50 and 35 min, respectively. The plasma insulin response of complete nutrition drink was continuously remained higher than baseline throughout the 3-h period. In contrast, the insulin response to glucose solution and white bread were rapidly declined. Nevertheless, there were no statistically significant differences among groups. Table S2 shows that the average AUCi of insulin response for complete nutrition drink (mean ± SE: 6317±1788, 95% CI: 2544, 10089) was higher than that of glucose solution (mean ± SE: 5710±1880, 95% CI: 1743, 9677) but lower than that of white bread (mean ± SE: 11378±4690, 95% CI: 1483, 21274). However, no statistically significant differences were observed among groups. The average maximum insulin concentrations of complete nutrition drink, white bread, and glucose solution were 96.19, 123.51, and 69.5 uIU/ mL, respectively.
Responders VS non-responders
Responders were the subjects showing low glycemic index of the complete nutrition drink, while the non-responders showed medium or high glycemic index. Table 5 showed the list of responders and non-responders of complete nutrition drink. Responders were distributed in all three randomized groups suggesting that the sequence of intervention did not affect the response.
With regard to the factors affecting response to the low GI complete nutrition drink, baseline characteristics and dietary intakes were compared between responder and non-responder groups. Low-GI response correlated with only baseline insulin (r = 0.4997, p = 0.0347), but was independent of fasting plasma glucose (r = 0.0456, p = 0.8574) (Table 6). The correlation coefficients of the other variables are listed in Table 6. Interestingly, baseline plasma insulin level was the only parameter showing difference between groups. The average baseline insulin levels (mean ± SE) in the responder group was 14.86 ± 4.77 µIU/mL (95% CI: 4.36-25.35), which was significantly higher than that of the non-responder group (p-value = 04, mean ± SE: 4.89 ± 1.39 µIU/mL; 95% CI: 1.3 – 8.48). The effect size was 2.7. In contrast, there were no statistically significance differences for other factors including fiber intake, protein intake, age, HbA1C, BMI and HDL-C ratio, between responders and non-responder groups (Figure 3).
Dietary intake and physical activity
Figure 4 showed that there were no statistically significant differences of energy, protein dietary intake and percentage of energy distribution from carbohydrate, and physical activity levels between two washout periods (P-value ≥ 0.05).
Throughout the entire study, there were no adverse events occurring with any participants.