TABLE 3.

Summary of findings and conclusions for a more targeted use of DF supplements¹

Immunometabolic marker	DF dose	DF physicochemical properties	Intervention duration	Placebo	Conclusions
Dysglycemia and insulin resistance
Glucose	No effect of dose detected.	No clear pattern.	Longer durations of ≥13 wk resulted in an effect more often (61, 77, 93, 94, 111).	Placebo appeared not to confound findings.	Supplement DF for longer durations (≥13 wk).
Glucose AUC	Insufficient information available.	Insufficient information available.	Interventions ≤4 wk showed no effect.	Placebo had a strong confounding effect (61, 68). Inert compounds should be used.	Very limited information available, but interventions may need to be ≥5 wk. Given the negative effect of digestible CHO on hyperglycemia, benefits could be achieved by their replacement with DF.
Insulin	Little effect at any dose.	Little effect of any DF type.	Little effect with any intervention duration.	Insufficient data provided to determine the effect of the placebo.	DF supplementation, as currently used, does not appear to influence fasting insulin.
Insulin AUC	Insufficient information available.	Insufficient information available.	Insufficient information available.	Placebo had a strong confounding effect (64, 66).	Very limited information available. Given the negative effect of digestible CHO on hyperinsulinemia, benefits could be achieved by their replacement with DF.
HOMA-IR	No effect of dose detected.	No difference in DF type detected.	Durations between 5 and 12 wk resulted in an effect more often (51, 52, 58, 86, 95).	Placebo appeared not to confound findings.	Supplement DF for ≥5 wk.
Inflammation
CRP	Little effect at doses ≤20 g/d; however, there was evidence of a dose response. Higher DF dose interventions resulted in an effect more often (91, 121).	Insufficient information available.	Little effect for durations <13 wk. Studies of ≥13 wk administration showed an effect more often (103).	No placebo-controlled interventions included in this review showed an effect. However, digestible CHO have been shown to induce inflammation (61, 151); therefore, inert compounds should be used.	Supplement higher doses of DF (>20 g/d) for longer durations (≥13 wk). Given the proinflammatory effect of digestible CHO, benefits could be achieved by their replacement with DF.
IL-6	Insufficient information available.	Insufficient information available.	Insufficient information available.	Placebo had a detrimental effect that confounded the true effect of DF supplementation (61). Inert compounds should be used.	Overall, insufficient information is available to make recommendations. Further research needs to be conducted assessing the effect of replacing digestible CHO with DFs.
Dyslipidemia
TC	Lower doses were sufficient to reduce this marker, but doses ≥20.1 g/d resulted in an effect more often (76, 91, 92, 97, 106).	Viscous and mixed plant cell wall DF types resulted in an effect more often (47, 56, 80, 91, 105).	Short intervention durations (2–4 wk) were sufficient to reduce this marker (56, 79, 91, 115, 122).	Placebo had little effect; overall, did not confound findings.	Supplement higher doses of DF (≥20.1 g/d) for 2–4 wk. Use viscous or mixed plant cell wall DFs.
LDL-C	Lower doses were sufficient to reduce this marker, but doses ≥20.1 g/d resulted in an effect more often (55, 57, 91, 97, 114).	Viscous and mixed plant cell wall DF types resulted in an effect more often (48, 51, 70, 84, 123).	Short intervention durations (2–4 wk) were sufficient to reduce this marker (56, 79, 98, 104, 122).	Placebo had little effect; overall, did not confound findings.	Supplement higher doses of DF (≥20.1 g/d) for 2–4 wk. Use viscous or mixed plant cell wall DFs.
HDL-C	Little effect at any dose.	Little effect of any DF type.	Little effect at any intervention duration.	Insufficient information available.	DF supplementation does not appear to increase HDL-C.
TG	Little effect at any dose, but doses ≥20.1 g/d resulted in an effect more often (58, 76, 91, 114).	Little effect of any DF type, but mixed plant cell wall DFs resulted in an effect more often (56, 76, 90, 91, 114).	Little effect with any intervention duration.	Insufficient data provided to determine the effect of the placebo.	DF supplementation, appears to effect TG minimally as currently used, but higher doses of mixed plant cell wall DFs may improve results.

¹CHO, carbohydrates; CRP, C-reactive protein; DF, dietary fiber; HDL-C, HDL cholesterol; LDL-C, LDL cholesterol; TC, total cholesterol; TG, triglycerides.