Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, 157 Baojian Road, Nangang District, Harbin, Heilongjiang Province, 150081, People's Republic of China.
Diabetologia. 2018 Sep;61(9):1985-1995. doi: 10.1007/s00125-018-4674-3. Epub 2018 Jul 3.
AIMS/HYPOTHESIS: The association between dietary Mn and type 2 diabetes is unclear. We aimed to elucidate whether dietary Mn is associated with type 2 diabetes, to investigate whether this association is independent of dietary total antioxidant capacity (TAC) and to explore the underlying mechanisms in their association.
Two prospective cohorts of 3350 and 7133 Chinese adults (20-74 years old) were enrolled including, respectively, 244 and 578 individuals newly diagnosed with type 2 diabetes, with mean values of 4.2 and 5.3 years of follow-up. Cox's proportional-hazards regression and linear regression were performed to investigate the association between dietary Mn and type 2 diabetes (diagnosed by OGTT) or HbA and to analyse the joint association between dietary Mn and TAC. Restricted cubic spline (RCS) regression was applied to the non-linear association between dietary Mn and incidence of type 2 diabetes. Mediation analysis was applied to explore potential mediators in their association in a subgroup of 500 participants.
Dietary Mn intakes were 4.58 ± 1.04 and 4.61 ± 1.08 (mean ± SD) mg/day in the two cohorts. Dietary Mn was inversely associated with type 2 diabetes incidence and HbA concentration in both cohorts (p < 0.01 and <0.01 for type 2 diabetes, and p < 0.01 and =0.02 for HbA, respectively, in each cohort) independent of TAC, adjusted for age, sex, BMI, tobacco use, alcohol consumption, physical activity, diabetes inheritance, total energy, carbohydrate, total fatty acids, fibre, calcium, Mg, hypertension, hyperlipidaemia, and impaired glucose tolerance or FBG (all at baseline). Their inverse association was stronger in the presence of diets with high, compared with low, TAC. In RCS, intakes of >6.01 and 6.10-6.97 mg/day were associated with a significantly lower type 2 diabetes incidence in the two respective cohorts. Mediation analysis showed that high plasma Mn and low oxidative stress (increased Mn superoxide dismutase and decreased 8-hydroxydeoxyguanosine) contributed to the association between dietary Mn and both type 2 diabetes and HbA.
CONCLUSIONS/INTERPRETATION: Dietary Mn was inversely associated with type 2 diabetes independently of TAC. In addition, this association was stronger in a high- rather than low-TAC diet. Plasma Mn and oxidative stress were mediators in the association between dietary Mn and type 2 diabetes. Future studies on absolute Mn intake should be conducted to study the potential non-linearity and optimal levels of dietary Mn and type 2 diabetes.
目的/假设：膳食锰与 2 型糖尿病之间的关系尚不清楚。我们旨在阐明膳食锰是否与 2 型糖尿病有关，研究这种关联是否独立于膳食总抗氧化能力（TAC），并探讨它们之间关联的潜在机制。
我们纳入了两个队列的 3350 名和 7133 名中国成年人（20-74 岁），分别有 244 名和 578 名新诊断为 2 型糖尿病的患者，随访时间分别为 4.2 年和 5.3 年。我们使用 Cox 比例风险回归和线性回归来研究膳食锰与 2 型糖尿病（通过 OGTT 诊断）或 HbA 的关系，并分析膳食锰与 TAC 的联合关联。限制性立方样条（RCS）回归用于研究膳食锰与 2 型糖尿病发病率之间的非线性关联。在 500 名参与者的亚组中，我们进行了中介分析，以探讨它们之间关联的潜在中介因素。
两个队列的膳食锰摄入量分别为 4.58 ± 1.04 和 4.61 ± 1.08（均数 ± 标准差）mg/天。膳食锰与两个队列中的 2 型糖尿病发病率和 HbA 浓度呈负相关（p < 0.01 和 <0.01 用于 2 型糖尿病，p < 0.01 和 =0.02 用于 HbA，在每个队列中），独立于 TAC，调整了年龄、性别、BMI、吸烟、饮酒、体力活动、糖尿病遗传、总能量、碳水化合物、总脂肪酸、纤维、钙、Mg、高血压、高脂血症和葡萄糖耐量受损或 FBG（均在基线时）。与低 TAC 饮食相比，高 TAC 饮食中膳食锰的摄入量与 2 型糖尿病的发病率显著降低有关。在 RCS 中，>6.01 和 6.10-6.97mg/天的摄入量与两个队列中 2 型糖尿病发病率的显著降低相关。中介分析表明，高血浆锰和低氧化应激（增加锰超氧化物歧化酶和减少 8-羟基脱氧鸟苷）导致膳食锰与 2 型糖尿病和 HbA 之间的关联。
结论/解释：膳食锰与 2 型糖尿病呈负相关，独立于 TAC。此外，这种关联在高 TAC 饮食中比低 TAC 饮食中更强。血浆锰和氧化应激是膳食锰与 2 型糖尿病之间关联的中介因素。未来应该进行关于绝对锰摄入量的研究，以研究膳食锰和 2 型糖尿病之间的潜在非线性和最佳水平。
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