Total magnesium intake and risk of frailty in older women.

Background: An adequate magnesium intake might lower the risk of frailty through its role in muscle function.

Methods: We analysed data from 81 524 women aged ≥60 years participating in the Nurses' Health Study. Total magnesium intake was obtained from repeated food frequency questionnaires administered between 1984 and 2010 and self-reported information on supplementation. Frailty was defined as having at least three of the following five FRAIL scale criteria: fatigue, low strength, reduced aerobic capacity, having ≥5 chronic illnesses and weight loss ≥ 5%. The occurrence of frailty was assessed every 4 years from 1992 to 2018. Cox proportional hazards models adjusted for lifestyle factors, medication use and dietary factors were used to assess the association between magnesium intake and frailty.

Results: During a median follow-up of 16 years, we identified 15 477 incident cases of frailty. Women with a higher intake of total energy-adjusted magnesium had a decreased risk of frailty after adjustment for lifestyle factors, medication use and dietary factors. The relative risk (95% confidence interval) for Quintile 5 (Q5) versus Quintile 1 (Q1) was 0.88 (0.82, 0.94) (P-trend < 0.001). When only energy-adjusted magnesium from the diet was considered, the inverse association was stronger (Q5 vs. Q1: 0.68 [0.56, 0.82]; P-trend < 0.001). Those reaching the recommended daily allowance (RDA) of magnesium through diet had a 14% (9%, 19%) lower risk of frailty compared with those not meeting the RDA.

Conclusions: Increased intake of foods rich in magnesium was associated with a decreased risk of frailty.