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Association between carbohydrate quality and inflammatory markers: systematic review of observational and interventional studies.
Buyken, AE, Goletzke, J, Joslowski, G, Felbick, A, Cheng, G, Herder, C, Brand-Miller, JC
The American journal of clinical nutrition. 2014;(4):813-33
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Abstract
BACKGROUND Chronic low-grade inflammation is a likely intermediary between quality of carbohydrate and chronic disease risk. OBJECTIVE We conducted a systematic literature search to evaluate the relevance of carbohydrate quality on inflammatory markers in observational and intervention studies. DESIGN MEDLINE, EMBASE, and the Cochrane Library were searched for studies on associations between glycemic index (GI), glycemic load (GL), dietary fiber or fiber supplements or whole grain intake, and high-sensitivity C-reactive protein (hsCRP) or interleukin 6 (IL-6). Included studies had to be conducted on adults (healthy, overweight, with type 2 diabetes or metabolic syndrome features, but without inflammatory disease) with ≥20 participants and a 3-wk duration. RESULTS In total, 22 of the 60 studies that met our inclusion criteria examined GI/GL: 5 of 9 observational studies reported lower concentrations of hsCRP or IL-6 among persons with a lower dietary GI/GL; 3 of 13 intervention studies showed significant antiinflammatory effects of a low-GI/GL diet, and 4 further studies suggested beneficial effects (trends or effects in a subgroup). For fiber intake, 13 of 16 observational studies reported an inverse relation with hsCRP or IL-6, but only 1 of 11 intervention studies showed a significant antiinflammatory effect of fiber intake, and a further trial reported a beneficial trend. For whole-grain intake, 6 of 7 observational studies observed an inverse association with inflammatory markers, but only 1 of 7 intervention studies reported significant antiinflammatory effects, 1 further study was suggestive (in a subgroup) of such, and another study found an adverse effect (trend only). CONCLUSIONS Evidence from intervention studies for antiinflammatory benefits is less consistent for higher-fiber or whole-grain diets than for low-GI/GL diets. Benefits of higher fiber and whole-grain intakes suggested by observational studies may reflect confounding.
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Effects of PGX, a novel functional fibre, on acute and delayed postprandial glycaemia.
Brand-Miller, JC, Atkinson, FS, Gahler, RJ, Kacinik, V, Lyon, MR, Wood, S
European journal of clinical nutrition. 2010;(12):1488-93
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Abstract
BACKGROUND Viscous fibre in food has established health benefits, but few functional fibre preparations are both effective and palatable. Our objective was to determine the most effective dose, formulation and timing of consumption of a novel fibre supplement (PolyGlycopleX (PGX)) in reducing postprandial glycaemia. SUBJECTS/METHODS Three trials were undertaken, each with 10 subjects (8M and 8F; age 24.4 ± 2.6 years). Granular supplement was tested at four doses (0, 2.5, 5.0 and 7.5 g) with breakfast (study 1). Granular and capsule forms of the supplement were given in a single dose (5 g for granules and 4.5 g in capsules) at -60, -45, -30, -15 and 0 before, and +15 min after a bread meal (study 2). Capsules at increasing doses (1.5, 3, 4.5 and 6 g) were consumed with the evening meal to determine effects on glucose tolerance at breakfast (study 3). Incremental area under the blood glucose curve was determined. RESULTS Granular PGX at breakfast time at doses of 2.5, 5 and 7.5 g reduced the incremental area under the curve by up to 50% in a linear dose-response fashion (P<0.001). The granular form of PGX (5 g), but not the capsules, reduced glycaemia by up to 28% when consumed from -45 to +15 min (P<0.001). Capsules containing 3, 4.5 and 6 g PGX consumed with the evening meal reduced glycaemia at breakfast by up to 28% (P<0.001). CONCLUSIONS PGX has biologically important, dose-related effects on acute and delayed (second meal) postprandial glycaemia.