Table 1.
Clinical studies regarding the effect of high fiber intake on inflammatory markers in obesity and associated pathology.
| Design | Population | Dietary Intervention | Outcome | Reference |
|---|---|---|---|---|
| Randomized cross-over trial | 50 Danish subjects with high risk of metabolic syndrome | two eight-week dietary intervention periods of whole grain intake (179 ± 50 g/day) and refined grain period (maximum 13 ± 10 g/day of whole grain), separated by a washout period of ≥6 weeks. | ↓ body weight, serum inflammatory markers (IL-6, CRP) | [101] |
| Double-blind, randomized, placebo-controlled, crossover study | 45 overweight adults with metabolic syndrome risk factors | galactooligosaccharide mixture intervention to increase dietary fiber content, with a 4-week wash-out period between interventions | ↓ fecal calprotectin, CRP | [102] |
| Randomized controlled trial | 143 individuals with metabolic syndrome | 12 weeks of rye and whole wheat was compared with a diet containing the equivalent amount of refined cereal foods | no significant effects on the expression of inflammatory markers’ genes or insulin sensitivity | [103] |
| Randomized crossover study | 19 adults with metabolic syndrome | 4-week interventions diet enriched with arabinoxylan and resistant starch compared to a low-fiber Western-style diet | ↓ fecal calprotectin, IL-23A and NF-κB | [104] |
| Crossover intervention study | 25 hypercholesterolemic subjects | 5-week intervention using high fiber (HF) and low fiber (LF) diet, separated by a 3-week washout. | ↓ CRP and fibrinogen | [105] |
| Randomized controlled trial | 68 overweight with prediabetes | 12 weeks of 45 g/d of high-amylose maize (RS2) versus an isocaloric amount of amylopectin (control) | ↓ TNF-α, no change in insulin sensitivity |
[106] |
| Randomized controlled trial | 166 subjects with features of metabolic syndrome | 4-week using healthy diet (whole-grain products, berries, fruits and vegetables, rapeseed oil, three fish meals per week) compared to an average Nordic diet | Control diet: ↑ IL-1 Ra (versus healthy diet group) | [107] |
| Crossover study | 10 healthy subjects | Subjects received either 910-calorie high-fat/high-carbohydrate meal or an American Heart Association (AHA) meal (fruit and fiber) during the first visit and the other meal during the second visit | ↑ oxidative stress (plasma concentrations of TBARS, FFA, and LPS) and proinflammatory markers (TNFα, and IL-1β) | [108] |
| Randomized controlled trial | 28 T2DM patients | Subjects received brown rice (n = 14) or white rice (n = 14) diet for 8 weeks | ↓ CRP in brown rice group | [109] |
| Parallel design, dietary intervention trial | 104 subjects with metabolic syndrome risk | Subjects received Healthy Diet (n = 44), a whole-grain-enriched diet (n = 42) or a control (n = 45) diet, | Healthy Diet group: ↓ E-selectin Healthy Diet and whole grain group: ↓ CRP |
[110] |
| Randomized, double-blind, placebo-controlled, cross-over study | 12 overweight and obese subjects | Subjects received 20 g/day of inulin-propionate ester, a high-fermentable fiber control (inulin) and a low-fermentable fiber control (cellulose) for 42 days | IPE: ↓ IL-8 levels (versus cellulose) Inulin: no effect on the inflammatory markers | [111] |
| Crossover clinical study | 18 subjects at low-to-moderate cardiometabolic risk | Subjects received breakfast rich in saturated fatty acids (SFA), the other in unsaturated fatty acids (unSFA) and fiber for 4 weeks | SFA: ↑ IL-1β unSFA: ↓ IL-6 |
[112] |
| Interventional diet study | 21 overweight/obese children | Subjects were placed on a regimen of ad libitum, high-fiber, low-fat diet, and daily exercise regimen for 2 weeks | ↓ IL-6, IL-8, TNFα, PAI-1, resistin, amylin, leptin, insulin, and IL-1Ra ↑ adiponectin |
[113] |
| Randomized, placebo-controlled study | 31 hemodialysis patients | Patients received either resistant starch or placebo supplementation for 4 weeks | ↓ IL-6 and TBARS | [114] |
| Randomized controlled clinical trial | 55 women with T2DM | Subjects received a daily supplement of 10 g resistant dextrin or a similar amount of maltodextrin for 8 weeks | ↓ IL-6, TNF-α and MDA ↑ Insulin sensitivity |
[115] |
| Randomized cross-over double-blind placebo-controlled trial | 17 obese knee osteoarthritis patients | Patients received freeze-dried strawberries or placebo for 2 periods of 12 weeks with 2 weeks of wash-out | ↓ TNF-α and 4-HNE | [116] |
| Randomized study | 59 T2DM patients | Patients received metformin, acarbose, and either a high fiber or a low fiber diet intervention for 8 weeks | Low fiber group: ↓ IL-18 | [117] |
| Crossover study | 33 healthy, middle-aged adults | Patients received either high or low in in wholegrain intervention for 6-week periods, separated by a 4-week washout. | Whole grain: a slight decrease of IL-10 and CRP | [118] |
| Observational study | 8 subjects with impaired fasting glucose | subjects received (1) high-fiber formula; (2) high-monounsaturated fatty acid formula or (3) control formula | High fiber group: ↓ NF-κB in PBMCs | [119] |
| Randomized controlled clinical trial | 60 females with T2DM | Patients received 10 g/d resistant starch or placebo for 8 weeks, respectively | ↓TNF-α, no effect on IL-6 or CRP | [120] |
| Crossover clinical trial | 80 overweight subjects | Subjects received two isocaloric breakfast interventions -one rich in saturated fat and one in unsaturated fatty acids and fibers for 4 weeks with a 2-weeks washout. | Fiber group: ↓ IF-γ and TNF-α | [112] |
| Observational study | 49 T2DM females | Patients received either 10 g/day inulin or maltodextrin/day for 8 weeks | Inulin: ↓CRP, TNF-α and LPS | [121] |
| Randomized controlled clinical trial | 52 overweight/obese women with T2DM | Patients received either 10 g/d of oligofructose-enriched inulin or maltodextrin (control) for 8 weeks | oligofructose-enriched-Inulin: ↓ CRP, TNF-α and LPS | [122] |
| Randomized crossover clinical trial | 44 overweight/obese girls 8–15 years old | Subjects received either whole-grain or control for 2 periods of 6 weeks with 4-week washout period | Whole grain: ↓ CRP, ICAM-1 and leptin | [123] |
IL-6, IL-1β, IL-6, IL-8, IL-18, IL-10—interleukin 6, 1β, 6, 8, 18, 10; IL-1 Ra—interleukin 1 receptor agonist; CRP—C reactive protein; NF-κB—nuclear factor kappa B; TNF-α—tumor necrosis factor α; TBARS—thiobarbituric acid reactive substances; FFA—free fatty acids; LPS—lipopolysaccharide; MDA—malondialdehyde; 4-HNE—4-hydroxynonenal; IF-γ—interferon γ; ICAM-1—intercellular adhesion molecule 1.