The anti-inflammatory effects induced by polyphenols in human studies with dietary interventions and weight related outcomes are heterogeneous, as summarized from recent literature (Table 7 ). Thus, in a clinical study with double-blind, randomized, cross-over design, the effect of a commercially available polyphenols rich extract was tested, the study including patients having more than two metabolic risk factors. Results showed a reduction of MCP-1 and MIF, but not of other markers of CVD risk (CRP, IL-6, HDL, adiponectin and oxidized LDL) (Broekhuizen et al., 2011). In a separate clinical study with cross-over design, overweight patients consumed a high-carbohydrate, moderate-fat meal supplemented with strawberry/placebo juice. The anthocyanin supplementation blunted the postprandial inflammatory response (reduced CRP level) induced by the high fat diet and reduced the postprandial insulin response (Edirisinghe et al., 2011). Furthermore, a double-blind study focused on hypercholesterolemia subjects, receiving a purified anthocyanin mixture, resulted in a reduction of their CRP, sVCAM-1 and IL-1β levels. Similar results were obtained for HepG2 and porcine iliac artery endothelial cells exposed to the same purified anthocyanin mixture (reduction of LPS-induced VCAM-1 secretion) (Zhu et al., 2013). Patients with early atherosclerosis, received simple or EGCG-enriched olive oil. Independent of EGCG addition, olive oil reduced inflammatory markers and endothelial dysfunction (sICAM, white blood cells, monocytes, lymphocytes and platelets) (Widmer et al., 2013).
Table 7 Clinical data regarding the efficacy of polyphenols on inflammatory phenomena.
Design Population Type of intervention Inflammatory outcome Reference
Randomised, double-blind, cross-over study 34 subjects with two or more metabolic risk factors 4-week intervention: 500 mg polyphenols/day vs. placebo ↓MCP-1 and MIF, unchanged levels of HDL, adiponectin, CRP Broekhuizen et al. (2011)
Cross-over study 24 overweight adults high-carbohydrate, moderate-fat meal together with a strawberry beverage (SB) or placebo SB:↓ CRP and postprandial insulin Edirisinghe et al. (2011)
Randomised, double-blind 150 hypercholesterolemic subjects 24-week intervention: 640 mg purified Anthocyanin/day ↓ CRP, sVCAM-1 and IL-1β Zhu et al. (2013)
Randomised, double-blind 52 patients with early atherosclerosis, 4-month intervention: 30 mL olive oil or 30 ml of EGCG-supplemented olive oil ↓ sICAM, white blood cells, monocytes, lymphocytes and platelets Widmer et al. (2013)
Single-centre, randomised, two-arm, double-blinded, placebo-controlled study 36 pre-hypertension patients, randomized to control or treatment groups 6-week intervention: grape seed extract, 150 mgx2/day ↓BP (SBP, DBP)↑ fasting insulin and insulin sensitivityNo change of sICAM-1 Park et al. (2016)
Single blinded crossover trial 38 patients with untreated mild hypertension 8-week intervention: 300 mL/day cold-pressed 100% chokeberry juice and 3 g/day chokeberry powder ↓IL-10 and TNF-α Loo et al. (2016)
Randomized, double-blind, placebo-controlled clinical trial 50 hyperlipidemic patients 4-week intervention: V. arctostaphylos fruit extract x2/day no effects on HDL and CRP↓ total cholesterol, LDL-C, TG, MDA Soltani et al. (2014)
Placebo controlled study 20 study subjects and 19 placebo 4-week intervention: 361 mg polyphenols and 120 mg vitamin C x2/day No significant effects on apolipoproteins, adiponectin, CRP, ICAM-1, E-Selectin or t-PA Mullan et al. (2016)
Placebo controlled study 16 trained cyclists 7-day intervention: 30 mL of Montmorency tart cherry concentrate x 2/day ↓lipid hydroperoxides, IL-6 and hsCRP Bell et al. (2014)
Double-blind crossover study 49 healthy male subjects with APOE genotype 8-week intervention: 150 mg/day quercetin or placebo (3 phases, three-week washout periods) ↓ waist circumference and postprandial SBP, moderately increased levels of TNFα Pfeuffer et al. (2013)
Randomised, double-blind, placebo-controlled, cross-over trial 18 healthy volunteers One-tine administration of 51 mg of oleuropeine ↓of IL8 production Lockyer et al. (2015)
Cross-sectional study 1997 females Frequency questionnaires assessment of total intake of flavonoids Higher anthocyanin and flavone intake were associated with significantly lower peripheral insulin resistanceHigher anthocyanin intake was also associated with lower CRP concentrationsHigher anthocyanin-rich intake was associated with lower insulin and inflammation Jennings et al. (2014)
Randomized, controlled dietary study 27 subjects with metabolic syndrome 400 g fresh bilberries/days vs. control diet ↓ CRP, IL-6, IL-12, Kolehmainen et al. (2012)