by Ashley Jordan Ferira, PhD, RDN
Recent research from three well-known cohorts, The Nurses’ Health Study (NHS), NHS2 and Health Professionals’ Follow-Up Study (HPFS), reveals that higher magnesium intake is associated with lower risk of type 2 diabetes (T2D), particularly in diets with poor carbohydrate quality.1
Green leafy vegetables, unrefined whole grains, and nuts are richest in magnesium, while meats and milk contain a moderate amount.2 Refined foods, like carbohydrates (carb), are poor sources of magnesium. Diets with poor carb quality are characterized by higher glycemic index (GI), higher glycemic load (GL), and lower fiber intake. These poor carbs require a higher insulin demand.
The typical American diet is low in vegetables and whole grains, resulting in reduced magnesium intake. The Recommended Daily Allowance (RDA) for magnesium is 310-320 mg/day for adult women and 400-420 mg/day for adult men.3 Half of the US population fails to meet their daily magnesium needs, and hypomagnesemia exists in 1/3 of adults.4-5 Magnesium is needed for normal insulin signaling; current research has linked insufficient magnesium intake to prediabetes, insulin resistance and T2D.4 Increased magnesium intake has been inversely associated with T2D risk in observational studies.6
Collaborators from Tufts University, Harvard University, and Brigham and Women’s Hospital, sought to investigate the impact of magnesium intake, from both dietary and supplemental sources, on the risk of developing T2D in subjects who had diets with poor carb quality and raised GI, GL, or low fiber intake.1 They followed three large prospective cohorts, NHS, NHS2 and HPFS (totaling over 202,700 participants). Dietary intake was quantified by validated food frequency questionnaires (FFQ) every 4 years, and T2D cases were captured via questionnaires. Over 28 years of follow-up, there were 17,130 cases of T2D.
Major study findings included:1
Similar to the US population estimates, 40-50% of study participants had inadequate magnesium intake. A healthful, varied diet and supplemental magnesium (especially in diets that restrict or exclude carbohydrates, dairy or meat) are essential to ensure sufficient daily magnesium intake.
Why is this Clinically Relevant?
Link to Abstract