Dietary magnesium intake is related to larger brain volumes and lower white matter lesions with notable sex differences

Abstract

Purpose: To examine the association between dietary magnesium (Mg) intake and brain volumes and white matter lesions (WMLs) in middle to early old age.

Methods: Participants (aged 40-73 years) from UK Biobank (n = 6001) were included and stratified by sex. Dietary Mg was measured using an online computerised 24 h recall questionnaire to estimate daily Mg intake. Latent class analysis and hierarchical linear regression models were performed to investigate the association between baseline dietary Mg, Mg trajectories, and brain volumes and WMLs. Associations between baseline Mg, and baseline blood pressure (BP) measures, and baseline Mg, Mg trajectories and BP changes (between baseline and wave 2) were also investigated to assess whether BP mediates the link between Mg intake and brain health. All analyses controlled for health and socio-demographic covariates. Possible interactions between menopausal status and Mg trajectories in predicting brain volumes and WMLs were also investigated.

Results: On average, higher baseline dietary Mg intake was associated with larger brain volumes (gray matter [GM]: 0.001% [SE = 0.0003]; left hippocampus [LHC]: 0.0013% [SE = 0.0006]; and right hippocampus [RHC]: 0.0023% [SE = 0.0006]) in both men and women. Latent class analysis of Mg intake revealed three classes: "high-decreasing" (men = 3.2%, women = 1.9%), "low-increasing" (men = 1.09%, women = 1.62%), and "stable normal" (men = 95.71%, women = 96.51%). In women, only the "high-decreasing" trajectory was significantly associated with larger brain volumes (GM: 1.17%, [SE = 0.58]; and RHC: 2.79% [SE = 1.11]) compared to the "normal-stable", the "low-increasing" trajectory was associated with smaller brain volumes (GM: - 1.67%, [SE = 0.30]; white matter [WM]: - 0.85% [SE = 0.42]; LHC: - 2.43% [SE = 0.59]; and RHC: - 1.50% [SE = 0.57]) and larger WMLs (1.6% [SE = 0.53]). Associations between Mg and BP measures were mostly non-significant. Furthermore, the observed neuroprotective effect of higher dietary Mg intake in the "high-decreasing" trajectory appears to be greater in post-menopausal than pre-menopausal women.

Conclusions: Higher dietary Mg intake is related to better brain health in the general population, and particularly in women.

Keywords: Blood pressure; Magnesium; Neuroimaging; Sex; UK biobank.

Fig. 1

Dietary Mg intake trajectories in men and women corresponding to different subgroups of individuals identified by latent class analysis. Note: “Time” is the number of waves across 16 months. Line intercept and slope are drawn from a linear model for each trajectory, with time as only predictor of Mg intake. Black lines represent the mean trend in each class. Coloured lines (red, green, or blue) correspond to the number of participants per class, and the slopes represent the change in Mg per unit of time. “n” is the number of participants in each class. The exploratory modelling and the Bootstrap Likelihood Ratio Test indicated that a three-class solution was optimal: class1 (“normal-stable”), class 2 (“high-decreasing”), and class 3 (“low-increasing”)

Fig. 2

Bar graph of the associations (beta values) between dietary magnesium (Mg) trajectories and a the brain volumes including gray matter, white matter, left hippocampus, right hippocampus, and white matter lesions; and b blood pressure (BP) including mean arterial pressure (MAP), systolic blood pressure (SBP), diastolic blood pressure (DBP), pulse pressure (PP) stratified by sex