Insulin resistance, whereby insufficient insulin is released to produce a normal glucose response from fat, muscle and liver cells, was significantly lower in people with metabolic syndrome with the highest average intakes of magnesium, according to findings published in Nutrients.
The study, by scientists from Yangzhou University in China and the University of Massachusetts Medical School, found that, of the 234 people included in the study, fewer than 30% of participants actually met the magnesium RDA, a statistic that corresponds with other data.
With between 70 and 80% of the US population not meeting their recommended intakes of magnesium, consumers – and the health care professionals who advise them - are waking up to the importance of the mineral.
The National Institutes of Health (NIH) lists magnesium as being necessary for more than 300 biochemical reactions in the body, from helping maintain normal muscle (with potential for sports nutrition) and nerve function, to keeping heart rhythm steady, supporting a healthy immune system, and keeping bones strong. The mineral is also needed for blood sugar management, and healthy blood pressure.
Far-reaching clinical implications
The new study involved non-diabetic people with metabolic syndrome (MetS), which is characterized by central obesity, hypertension, and disturbed glucose and insulin metabolism. The syndrome has been linked to increased risks of both type-2 diabetes and cardiovascular diseases.
The Centers for Disease Control and Prevention estimate that some 75 million Americans suffer from metabolic syndrome.
“This study observed a low percentage of participants who actually met the magnesium RDA, suggesting that increasing dietary magnesium to meet the RDA is associated with improving insulin resistance among non-diabetic individuals with MetS,” wrote the researchers.
“Since this population has a higher risk of cardiovascular disease and type-2 diabetes, dietary behaviors that have the ability to impact insulin resistance can have far-reaching clinical implications.”
The researchers assessed dietary magnesium intake for 234 people with MetS using 24-hour dietary recalls at the start of the study, and again after six and 12 months. Blood samples were taken and insulin resistance was estimated using the homeostasis model (HOMA-IR).
Results showed that dietary magnesium intake was inversely and statistically significantly associated with metabolic biomarkers of insulin resistance.
In addition, for people who met the RDA for magnesium, the risk of having elevated HOMA-IR results over time was decreased by 63%.
“Although previous studies have evaluated the protective effect of magnesium, satisfying the RDA is a simple message that can have important clinical meaning,” they wrote. “Our findings offer a unique contribution that meeting the RDA for magnesium may demonstrate a protective effect on insulin resistance.”
Magnesium in Europe
The European Food Safety Authority (EFSA) has issued positive opinions on magnesium and the maintenance of normal bone, teeth, and protein synthesis; the reduction of tiredness and fatigue; electrolyte balance; normal energy-yielding metabolism; neurotransmission, and muscle contraction.
The agency was not convinced by claims about magnesium and blood glucose, blood pressure, stress relief, protection of DNA, proteins and lipids from oxidative damage, the immune system and fat metabolism.
Despite negative opinions from EFSA, a number of meta-analysis and high-profile studies have been published in recent years supporting the mineral's benefits for metabolic pathways, blood pressure, reducing the risk of stroke, and reducing the risk of colon cancer.
2013, Volume 5, Number 10, Pages 3910-3919; doi:10.3390/nu5103910
“Dietary Magnesium Intake Improves Insulin Resistance among Non-Diabetic Individuals with Metabolic Syndrome Participating in a Dietary Trial”
Authors: J. Wang, G. Persuitte, et al.