Secular trends of dietary magnesium intakes among Chinese residents in 15 provincial-level administrative regions from 1991 to 2018

[Background] Magnesium is an important nutrient, and participates in most metabolic processes. Many studies show an association between dietary magnesium intakes and nutrition-related diseases such as diabetes. However, the data of dietary magnesium intakes and secular trends among the whole life cycle of Chinese residents are not available. [Objective] To investigate the dietary magnesium intakes and associated secular trends over the past three decades in residents of all ages and China, to identify the high-risk residents of magnesium deficiency and plan nutritional interventions, and provide basic data support for the revision of dietary magnesium reference intake. [Method] The data came from the 10 rounds of the "China Health and Nutrition Survey" from 1991 to 2018, and the participants with complete sociodemographic and dietary data wereselected. The median intakes, insufficient rates, and secular trends of dietary magnesium intakes were analyzed in different survey years. Analysis of multiple linear regression was used to analyze the annual change characteristics of dietary magnesium intakes controlling gender, age, education, urban-rural stratum, and north-south region. Wilcoxon trend test was used to analyze the secular trends of dietary magnesium intakes in different characteristic groups. The trends of insufficient rate were analyzed by Cochran-Armitage trend test among different characteristic groups. [Results] A total of 127169 residents were included in the present study. The medians of dietary magnesium intakes in 1991, 1993, 1997, 2000, 2004, 2006, 2009, 2011, 2015, and 2018 were 283.70, 283.38, 304.26, 285.50, 283.64, 275.49, 267.92, 242.93, 240.51, and 238.89 mg·d−1, respectively, showing a significant downward trend (F=2931.81, P