Is magnesium intake linked to brain health? Original paper

In this cross-sectional study, higher magnesium intake was associated with larger brain volumes and with lower white matter lesions.

The association between dietary magnesium intake and (i) brain volume and (ii) white matter lesions (areas of abnormality or damage in the white matter of the brain, which can be indicative of vascular diseases^[1]).

6,001 healthy adults (ages 40–73).

The researchers conducted a cross-sectional study using participant data from the UK Biobank. Participants were included in the summarized study if they completed baseline assessments (including basic health measures and dietary assessments that included magnesium intake) and underwent structural magnetic resonance imaging (MRI) scans at a follow-up assessment.

Using the MRI data, brain volume was further divided into the type of brain matter (white and gray matter) and brain region (e.g., volume of the left and right hippocampus), which were the primary outcomes.

The researchers analyzed whether sex and changing magnesium intakes over time (e.g., increasing, decreasing, or maintaining intake levels) influenced these outcomes.

The outcomes were further adjusted for lifestyle, cardiovascular, and sociodemographic risk factors.

Compared to lower levels of magnesium intake, higher intakes were associated with larger brain volumes, especially in the left and right hippocampus.

Each additional 1-milligram increase in dietary magnesium beyond 350 mg per day was associated with an increased volume of gray matter (+0.001%), left hippocampus (+0.013%), and right hippocampus (+0.023%). Moreover, every additional 1-milligram intake of magnesium beyond 350 mg per day was linked to lower white matter lesions in men (−0.001%) and larger white matter lesions in women (+0.0012%).

Compared to participants who did not change their magnesium intakes over time, the participants who decreased their dietary magnesium intake had greater brain volumes (in both men and women) but also larger white matter lesions (in women). In contrast, participants who increased their magnesium intake over time had smaller brain volumes but also showed larger white matter lesions.

(An addendum was made to this section based on reader feedback)

Given the overall protective association between magnesium intake and brain volume, it would appear unexpected that participants who increased their magnesium intake during the study had smaller brain volumes and, likewise, that participants who decreased their magnesium intake had greater brain volumes.

However, it’s important to keep in mind that participants who decreased their magnesium intake had a higher than average magnesium intake at the start of the study and, conversely, participants who increased their magnesium intake started out with a lower than average magnesium intake. It therefore could be that participants’ brain health was related to their previous, potentially long-term magnesium intake and not changes they made during the 16 months of examination.

Brain volume can be considered as a potential risk factor for certain aspects of aging, including cognitive decline.^[2] Several studies have suggested that reductions in brain volume, at least in certain regions, are associated with cognitive decline^[3] and an increased risk of age-related neurological disorders such as Alzheimer's disease.^[4]

That said, the findings from the summarized study provide evidence that magnesium might play a role in maintaining brain health, but more research from higher-quality studies is needed to further explore this hypothesis.