A low-glycemic index diet and exercise intervention reduces TNF(alpha) in isolated mononuclear cells of older, obese adults.
Study Goal
The researchers aimed to determine the combined effect of a low-glycemic-index diet and exercise on inflammation and glucose metabolism in insulin-resistant adults.
Results Summary
The low-glycemic-index diet combined with exercise reduced BMI, fasting plasma glucose, insulin, glycemic response, and inflammation markers (TNFα, IL-6, MCP-1), while the high-glycemic-index diet showed increased TNFα secretion.
Population
28 insulin-resistant adults (age: 66 ± 1 y; BMI: 34.2 ± 0.7 kg/m²).
Effective Dosage
Low-glycemic-index diet (LGI = 40) and aerobic exercise (5 days/week, 60 min/day, 80-85% heart rate max).
Duration
12 weeks
Interactions
None mentioned
| Intervention | Direction | Endpoint | Population | Dosage | Impact | Claim # |
|---|---|---|---|---|---|---|
low-glycemic index diet and exercise | decrease | BMI | insulin-resistant adults | P < 0.001 | decreased | #1 |
low-glycemic index diet and exercise | decrease | fasting plasma glucose | insulin-resistant adults | P = 0.01 | decreased | #2 |
low-glycemic index diet and exercise | decrease | fasting plasma insulin | insulin-resistant adults | P = 0.02 | decreased | #3 |
low-glycemic index diet and exercise | decrease | glycemic response | LGI group | P = 0.04 | reduced | #4 |
low-glycemic index diet and exercise | decrease | plasma TNFα | LGI group | P = 0.02 | reduced | #5 |
low-glycemic index diet and exercise | decrease | MNC-derived TNFα secretion | LGI group | P = 0.02 | reduced | #6 |
high-glycemic index diet and exercise | increase | plasma TNFα | HGI group | P = 0.02 | increased | #7 |
high-glycemic index diet and exercise | increase | MNC-derived TNFα secretion | HGI group | P = 0.02 | increased | #8 |
low-glycemic index diet and exercise | decrease | secretion of IL-6 from MNC | LGI group | - | reduced | #9 |
low-glycemic index diet and exercise | decrease | plasma IL-6 | LGI group | - | reduced | #10 |
low-glycemic index diet and exercise | decrease | plasma MCP-1 concentrations | LGI group | - | reduced | #11 |
low-glycemic index diet and exercise | decrease | inflammation and hyperglycemia | older, obese prediabetics | - | has antiinflammatory and antidiabetogenic effects | #12 |
Low-glycemic index diets and exercise independently improve glucose tolerance and reduce diabetes risk. However, the combined effect of a low-glycemic index diet and exercise on inflammation and glucose metabolism is not known. Therefore, we randomized 28 insulin-resistant adults (age: 66 ± 1 y; BMI: 34.2 ± 0.7 kg · m(-2)) to a 12-wk, low (LGI = 40) or high- (HGI = 80) glycemic index diet plus aerobic exercise (5 d · wk(-1), 60 min · d(-1), 80-85% heart rate(max)) intervention. All food and fluids were provided during the study. Inflammation was assessed from cytokine (TNFα and IL-6) secretion using peripheral blood mononuclear cells (MNC) stimulated overnight with LPS. Glycemic response was determined following ingestion of a 75-g glucose solution. Fasting blood samples were collected for additional cytokine [TNFα, IL-6, and monocyte chemoattractant protein 1 (MCP-1)] analysis. Both interventions decreased BMI (P < 0.001), fasting plasma glucose (P = 0.01), and insulin (P = 0.02). The glycemic response was reduced only in the LGI group (P = 0.04). Plasma and MNC-derived TNFα secretion were reduced in the LGI group (P = 0.02) but increased in the HGI group (P = 0.02). Secretion of IL-6 from MNC and plasma IL-6 and MCP-1 concentrations were reduced in the LGI group. The change in MNC-derived TNFα (r = 0.43; P = 0.04) and plasma MCP-1 (r = 0.44; P = 0.04) correlated with decreases in the glycemic response. These data highlight the importance of diet composition in the treatment and prevention of inflammation and hyperglycemia. A low-glycemic index diet has antiinflammatory and antidiabetogenic effects when combined with exercise in older, obese prediabetics.