Higher intake of dietary manganese lowers diabetes risk, finds new study

Higher is the intake of dietary manganese (Mn), lower is the risk for type 2 diabetes (T2D), according to a new study.

Results of the study, published in the journal Diabetologia, demonstrates an inverse relationship between dietary manganese and diabetes incidence independent of dietary total antioxidant capacity (TAC). In addition, this association was stronger in a high- rather than low-TAC diet.

Diet plays a major role in the management of T2D, with certain dietary supplements such as Mn linked to better glycemic control. Mn is primarily derived from food and is an essential micronutrient. Animal studies have demonstrated an association between low dietary Mn and impaired insulin secretion and glucose metabolism. However, few human studies have evaluated the effects of Mn supplementation on glucose metabolism.

Changhao Sun, Department of Nutrition and Food Hygiene, School of Public Health, Harbin Medical University, Harbin, China, and colleagues conducted the study to investigate whether the association between Mn and diabetes is independent of dietary total antioxidant capacity (TAC) and to explore the underlying mechanisms in their association.

For the study, the authors enrolled Two prospective cohorts of 3350 and 7133 Chinese adults (20-74 years old) that respectively included 244 and 578 individuals newly diagnosed with T2D, 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 HbAlc and to analyze 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.

Key Results:

• 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 HbAlc concentration in both cohorts 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 HbAlc.

"Our results demonstrate that 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," concluded the authors.

For further reference log on to https://doi.org/10.1007/s00125-018-4674-3