Journal of Endocrinology and Metabolism, ISSN 1923-2861 print, 1923-287X online, Open Access
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Review

Volume 8, Number 4, August 2018, pages 57-61


Effects of Glycemic Index and Intake of Dietary Fiber on Serum HDL-Cholesterol Levels

Tables

Table 1. Meta-Analyses Evaluated Effects of Glycemic Index on HDL-C
 
AuthorsAssessed studiesSubjects studiedEffects on HDL-CEffects on other lipids
CI, confidence interval; GI, glycemic index; HDL-C, high-density lipoprotein-cholesterol; LDL-C, low-density-cholesterol; MD, mean difference; RCT, randomized controlled trial; TC, total cholesterol; TG, triglyceride; WMD, weighted mean difference.
Schwingshackl L, et al [4]Meta-analyses were performed for each parameter to assess pooled effect in terms of WMD between the post-intervention of the low GI diets and the respective high GI counterparts9 studies enrolling 1065 children or adolescentsHDL-C under investigation was not affected by either low or high GICompared to diets providing a high GI, low GI protocols resulted in significantly more pronounced decreases in serum TG (-15.14 mg/dL, 95% CI: -26.26 to -4.00)
Fleming P, et al [5]RCTs on the effect of low-GI diets on serum lipid levels4 studiesThere was no significant effect on HDL-C levelsLow-GI diets were shown to have a significant effect on decreasing TC and LDL-C over a short time span (5 - 12 weeks). There was no significant effect on TG levels
Goff LM, et al [6]RCTs comparing low- with high GI diets over at least 4 weeks28 RCTs (1,272 participants; studies ranged from 6 to 155 participants)There was no effect on HDL-C (MD: -0.03 mmol/L, 95% CI: -0.06 - 0.00)Low GI diets significantly reduced TC (-0.13 mmol/L, 95% CI: -0.22 to -0.04, P = 0.004) and LDL-C (-0.16 mmol/L, 95% CI: -0.24 to -0.08, P < 0.0001) compared with high GI diets independently of weight loss. There was no effect on TG (MD 0.01 mmol/L, 95% CI: -0.06 to 0.08)
Kelly S, et al [7]RCTs that assess the relationship between the consumption of low GI diets over a minimum of 4 weeks and the effects on coronary heart disease and on risk factors for coronary heart disease15 RCTsThere is no evidence that low GI diets have an effect on HDL-CMeta-analysis detected limited and weak evidence of a relationship between low GI diets and slightly lower TC, compared with higher GI diets. There is no evidence that low GI diets have an effect on LDL-C and TG
Opperman AM, et al [8]RCTs with a crossover or parallel design, investigating the effect of low GI versus high GI diets on markers for carbohydrate and lipid metabolism16 studies (10 crossover design and 6 parallel design, n = 396)No change was observed in HDL-CLow GI diets significantly reduced TC by -0.33 (95 % CI: -0.47 to -0.18) mmol/L (P < 0.0001) and tended to reduce LDL-C in type 2 diabetic subjects by -0.15 (95% CI: -0.31 to -0.00) mmol/L (P = 0.06) compared with high GI diets. No change was observed in TG

 

Table 2. Meta-Analyses Evaluated Effects of Dietary Fiber Intake on HDL-C
 
AuthorsAssessed studiesSubjects studiedEffects on HDL-CEffects on other lipids
BMI, body mass index; CI, confidence interval; CVD, cardiovascular disease; HDL-C, high-density lipoprotein-cholesterol; LDL-C, low-density-cholesterol; MD, mean difference; NA, not available; RCT, randomized controlled trial; TC, total cholesterol; TG, triglyceride; WMD, weighted mean difference.
Ho HVT, et al [9]RCTs with a follow-up of ≥ 3 weeks that assessed the effect of konjac glucomannan (KJM) on LDL-C, non-HDL-C or apolipoprotein B12 studies (n = 370), 8 in adults and 4 in childrenNAKJM significantly lowered LDL-C (MD: -0.35 mmol/L; 95% CI: -0.46 to -0.25 mmol/L) and non-HDL-C (MD: -0.32 mmol/L; 95% CI: -0.46 to -0.19 mmol/L).Data from six trials suggested no impact of KJM on apolipoprotein B
Ho HV, et al [10]RCTs of ≥ 3-week duration assessing the effect of diets enriched with barley β-glucan compared with controlled diets on LDL-C, non-HDL-C or apoB14 trials (n = 615)NAA median dose of 6.5 and 6.9 g/day of barley β-glucan for a median duration of 4 weeks significantly reduced LDL-C (MD: -0.25 mmol/L (95% CI: -0.30 to -0.20)) and non-HDL-C (MD: -0.31 mmol/L (95% CI: -0.39 to -0.23)), respectively, with no significant changes to apoB levels, compared with control diets
Ho HV, et al [11]RCTs investigating the cholesterol-lowering potential of oat β-glucan on LDL-C, non-HDL-C and apoB58 trials (n = 3,974)NAA median dose of 3.5 g/day of oat β-glucan significantly lowered LDL-C (-0.19; 95% CI: -0.23 to -0.14 mmol/L, P < 0.00001), non-HDL-C (-0.20; 95% CI: -0.26 to -0.15 mmol/L, P < 0.00001) and apoB (-0.03; 95% CI: -0.05 to -0.02 g/L, P < 0.0001) compared with control interventions
Hartley L, et al [12]RCTs that assessed the effects of dietary fiber compared with no intervention or a minimal intervention on CVD and related risk factors23 RCTs (1,513 participants)There was a very small but statistically significant decrease rather than increase in HDL-C with increased fiber intake (MD: -0.03 mmol/L, 95% CI: -0.06 to -0.01)There is a significant beneficial effect of increased fiber on TC (MD: -0.23 mmol/L, 95% CI -0.40 to -0.06), and LDL-C (MD: -0.14 mmol/L, 95% CI: -0.22 to -0.06) but not on TG (MD: 0.00 mmol/L, 95% CI: -0.04 - 0.05)
Hollænder PL, et al [13]RCTs compared whole-grain foods with a non-whole-grain control in adults6,069 articlesNo effect of whole-grain foods on HDL-C was seenWhole-grain intake lowered LDL-C (WMD: -0.09 mmol/L; 95% CI: -0.15 to -0.03 mmol/L; P < 0.01) and TC (WMD: -0.12 mmol/L; 95% CI: -0.19 to -0.05 mmol/L; P < 0.001) compared with the control. Whole-grain foods tended to lower TG compared with the control (WMD: -0.04 mmol/L; 95% CI: -0.08 - 0.01 mmol/L; P = 0.10)
Zhu X, et al [14]RCTs that investigated the effects of beta-glucan consumption in hypercholesterolemic subjects17 eligible RCTs with 916 subjectsThere were no significant differences in HDL-CBeta-glucan consumption in hypercholesterolemic population significantly lowered TC (MD: -0.26 mmol/L; 95% CI: -0.33 to -0.18; P < 0.00001) and LDL-C (MD: -0.21 mmol/L; 95% CI, -0.27 to -0.14; P < 0.00001). There were no significant differences in TG
Onakpoya IJ, et al [15]RCTs examining the effectiveness of polyglycoplex (PGX), a novel functional fiber, on body weight and metabolic parameters4 RCTs with a total of 217 participantsThere was no significant difference between PGX and placebo for HDL-CSignificant reductions were noted for TC and LDL-C. There was no significant difference between PGX and placebo for TG
Whitehead A, et al [16]RCTs comparing ≥ 3 g oat β-glucan (OBG)/d with an appropriate control.28 RCTsThere was no significant effect of OBG on HDL-COBG in doses of ≥ 3 g/day reduced LDL-C and TC relative to control by 0.25 mmol/L (95% CI: 0.20 - 0.30; P < 0.0001) and 0.30 mmol/L (95% CI: 0.24 - 0.35; P < 0.0001), respectively. There was no significant effect of OBG on TG
Talati R, et al [17]RCTs of barley that reported efficacy data on at least 1 lipid endpoint8 trials (n = 391 patients) of 4 - 12 weeks’ duration evaluating the lipid-reducing effects of barleyThe use of barley did not significantly alter HDL-CThe use of barley significantly lowered TC (WMD: -13.38 mg/dL; 95% CI: -18.46 to -8.31 mg/dL), LDL-C (WMD: -10.02 mg/dL; 95% CI: -14.03 to -6.00 mg/dL) and TG (WMD, -11.83 mg/dL; 95% CI: -20.12 to -3.55 mg/dL)
Wei ZH, et al [18]This meta-analysis was primarily conducted to address the dose-response relationship between psyllium and serum cholesterol level and time-dependent effect of psyllium in mild-to-moderate hypercholesterolemic subjects21 RCTS, which enrolled a total of 1,030 and 687 subjects receiving psyllium or placebo, respectively, were included in the meta-analysis. The dose of psyllium was between 3.0 and 20.4 g/day and intervention period was more than 2 weeksHDL-C was significantly reduced, but only by a small amount (0.0353 mmol/L, 95% CI: 0.0003 - 0.0514).Compared with placebo, psyllium lowered serum TC by 0.375 mmol/L (95% CI: 0.257 - 0.494 mmol/L), and LDL-C by 0.278 mmol/L (95% CI: 0.213 - 0.312 mmol/L). A significant dose-response relationship was found between doses (3 - 20.4 g/day) and TC or LDL-C changes. There was a time effect of psyllium on TC and LDL-C. There was no significant effect on TG
Brown L, et al [19]RCTs which were performed to quantify the cholesterol-lowering effect of major dietary fibers.67 RCTsHDL-C was not significantly influenced by soluble fiberSoluble fiber (2 - 10 g/day) was associated with small but significant decreases in TC (-0.045 mmol/L/soluble fiber (g); 95% CI: -0.054 to -0.035) and LDL-C (-0.057 mmol/L/soluble fiber (g); 95% CI: -0.070 to -0.044). TG was not significantly influenced by soluble fiber