Influence of diet on leukocyte telomere length, markers of inflammation and oxidative stress in individuals with varied glucose tolerance: a Chinese population study

Nutrition Journal

Dec 2015

DOI: 10.1186/s12937-016-0157-x

Citations:68

Influential Citations:6

Observational Studies (Human)

Enhanced Details

Methods

556 Chinese adults without known diabetes underwent a 75 g OGTT and were categorized as normal glucose tolerance (n=200), pre-diabetes (n=197), or newly diagnosed diabetes (n=159); cross-sectional observational study. Dietary intake assessed by semi-quantitative FFQ. Leukocyte telomere length (LTL) measured by real-time PCR. Inflammatory markers (TNF-α, IL-6) and oxidative stress indicators (8-oxo-dG, SOD, GR) measured. Insulin resistance estimated by HOMA-IR; insulin secretion indices HOMA-β, DI30, and DI120 calculated.

Results

Telomere length differed by glucose status: longest in normal glucose tolerance, intermediate in pre-diabetes, shortest in newly diagnosed diabetes (log LTL: 2.01 ± 0.03, 1.97 ± 0.03, 1.89 ± 0.03). Among newly diagnosed diabetics, LTL adjusted for age was longer in HbA1c < 7% vs HbA1c ≥ 7% (log LTL 1.93 ± 0.25 vs 1.82 ± 0.29). LTL was not associated with daily energy intake or fat/carbohydrate proportions. Diet ingredients were linked to LTL: legumes, nuts, fish, and seaweeds associated with longer LTL; sweetened carbonated beverage associated with shorter LTL (β = 0.105, p = 0.018; β = 0.110, p = 0.011; β = 0.118, p = 0.007; β = 0.116, p = 0.009; β = −0.120, p = 0.004, respectively). After adjustment, these associations persisted. LTL correlated negatively with HbA1c and postprandial glucose (PG30′, PG60′, PG120′) and positively with DI30 and DI120. LTL showed relationships with inflammation and oxidative stress markers: higher energy intake associated with higher TNF-α (r=0.125, p=0.006) and IL-6 (r=0.092, p=0.04); fat and carbohydrate proportions associated with higher TNF-α; seaweeds and dairy intake linked to lower 8-oxo-dG; vegetables and fruits linked with higher GR. Conclusion: In Chinese adults with varied glucose tolerance, LTL is more strongly influenced by diet ingredients than by carbohydrate/fat proportions, and these ingredients modulate inflammation and oxidative stress that may affect LTL. Diabetes patients with better glycemic control have longer LTL, and LTL may reflect plasma glucose status in diabetes.

Limitations

Cross-sectional design; moderate sample size; dietary assessment via FFQ with potential recall bias; measurement variability in LTL assay; potential selection bias due to higher BMI and systolic BP; results cannot establish causality or generalize beyond studied population.

Abstract

ObjectivesTo explore influence of carbohydrates/fat proportions, dietary ingredients on telomere length shortening, oxidative stress and inflammation in a Chinese population with different glucose tolerance status.MethodsFive hundred and fifty-six Chinese subjects without diabetes history underwent a 75 g, 2 h Oral Glucose Tolerance Test (OGTT). Subjects with diabetes (n = 159), pre-diabetes (n = 197), and normal glucose tolerance (n = 200) were screened. Dietary intakes were evaluated using a semi-quantitative food frequency questionnaire (FFQ). Peripheral blood leukocyte telomere length (LTL) was assessed using a real-time PCR assay. Blood lipid profile, levels of the oxidative stress indicators superoxide dismutase (SOD), glutathione reductase (GR), 8-oxo-2′-deoxyguanosine (8-oxo-dG) and inflammation indicators tumor necrosis factor (TNF-ɑ), interleukine-6 (IL-6) were measured. Levels of HbA1c, plasma glucose, insulin, and C peptide were also determined. Measurements were taken at 0 min, 30 min, 60 min, and 120 min after 75 g OGTT. Insulin sensitivity was evaluated by HOMA-IR. Basal insulin secretion index (HOMA-β), early phase disposition index (DI30) and total phase disposition index (DI120) indicate insulin levels at different phases of insulin secretion.ResultsIn patients with newly diagnosed diabetes, LTL adjusted by age was longer in HbA1c < 7 % group (log (LTL):1.93 ± 0.25) than in HbA1c ≥ 7 % group (log (LTL):1.82 ± 0.29). LTL was not associated with daily energy intake, diet fat, carbohydrates and protein proportions. Multiple linear regression analysis indicated that legumes, nuts, fish and seaweeds were protective factors for LTL shortening, and sweetened carbonated beverage was a risk factor for LTL shortening ( legumes: β = 0.105, p = 0.018; nuts: β = 0.110, p = 0.011; fish: β = 0.118, p = 0.007; seaweeds: β = 0.116, p = 0.009; sweetened carbonated beverage: β = −0.120, p = 0.004 ). Daily energy intake was positively associated with TNF-ɑ, IL-6 (TNF-ɑ: r = 0.125, p = 0.006;IL-6: r = 0.092, p = 0.04). Fat, carbohydrate proportions were positively associated with TNF-ɑ (fat: r = 0.119, p = 0.008 ; carbohydrate: r = 0.094, p = 0.043). Seaweeds and dairy intake were negatively associated with 8-oxo-dG (seaweed: r = −0.496, p = 0.001;dairy: r = −0.246, p = 0.046 ), vegetables and fruits were positively associated with GR ( vegetables: r = 0.101, p = 0.034;fruits: r = 0.125, p = 0.045). Cereal, meat were positively associated with TNF-ɑ ( cereal: r = 0.091, p = 0.048 ; meat: r = 0.405, p = 0.009).ConclusionDiabetes patients with better plasma glucose (HbA1c < 7 %) had longer LTL, LTL could reflect plasma glucose status in diabetes patients. LTL were probably not influenced by diet carbohydrates/fat proportions but was associated with diet ingredients. Diet ingredients significantly impacted on markers of inflammation and oxidative stress, which probably had an effect on LTL. show less