Diet may play a major role in magnesium and its association to type 2 diabetes.
Nutrients and their effect on diabetes prevention have become a major topic of research in numerous studies. Magnesium is of significant interest because it has been recognized that almost half of the U.S. population has a magnesium deficiency. Low magnesium intake is also known to impair insulin function. Magnesium deficiency tends to be more distinct in individuals with prediabetes and diabetes. It has also been suggested that low magnesium intake results in an increased risk of prediabetes and diabetes development. Previous studies have shown that a higher magnesium intake does in fact result in decreased diabetes risk. However, few studies have analyzed how diet and carbohydrate quality affect this relation.
The following study analyzed data from three large cohorts conducted in the U.S called the Nurses’ Health Studies (NHS and NHS2) with a total of 160,647 participants and the Health Professionals Follow-up Study (HPFS) with a total of 42,096 participants. The study aimed to determine whether a higher magnesium intake results in type 2 diabetes risk reduction and how high glycemic index (GI) diets, those low in cereal fiber and high in carbohydrates, more specifically foods high in sugar and foods made with white flower, affect this association.
Participants in the three cohorts were followed for 28 years and evaluated for onset of type 2 diabetes. Food frequency questionnaires (FFQ) completed at baseline and every 4 years were utilized to obtain specific details on dietary intake. FFQs were used to calculate GI of food items and total magnesium intake. Both dietary and supplementary magnesium were used to calculate total magnesium intake. The primary end point was to identify onset of type 2 diabetes through analyzation of biennial and supplemental questionnaires that provided medical, lifestyle, and chronic disease history. Individuals who reported type 2 diabetes on the questionnaires were required to show evidence of diagnosis and had to meet specific criteria.
According to results, participants with higher magnesium intake were older, had lower BMIs, were more physically active, less likely to be smokers, and less likely to have high blood pressure when compared to participants with lower magnesium levels. Those with higher magnesium levels ingested more supplements, whole grains, and cereal fiber, and ingested less saturated fat, trans fat, and processed meat.
A total of 17,130 participants developed type 2 diabetes throughout the 28 years of follow-up. Cox proportional hazard models adjusted for age and other variables were used to determine the relation between magnesium intake and diabetes risk. Overall, participants with higher magnesium intake across all three cohorts were associated with a 15% lower risk of developing type 2 diabetes when compared to those with lower magnesium intake (combined hazard ratio(HR) 0.85 (95% CI, 0.80 to 0.91, P<0.0001)). Researchers also concluded that there is a 4% decrease in diabetes risk for each additional 50 mg intake of magnesium per day (combined HR 0.96 (95% Cl 0.95 to 0.98)). The relation between higher magnesium intake and reduced diabetes risk was more pronounced in participants with high GI or poor carbohydrate and low cereal fiber quality diets when compared to participants with low GI diets (P<.001).
This study showed that participants with high dietary and supplemental magnesium intake experienced a reduced risk of developing type 2 diabetes. It was also determined that participants with high GI or low cereal fiber — in other words, those with poor diets — who had higher magnesium intake, had a greater reduced risk of developing type 2 diabetes. This suggests that low magnesium intake can potentially predispose high risk patients to diabetes, especially if they have poor nutritional diets. The following findings were strengthened in that the study consisted of three large cohorts that were analyzed through a long period of 28 years with numerous follow-up questionnaires and measurements of dietary intake. However, questionnaires do not precisely determine magnesium and dietary intake. Also, being an observational study, there is a possibility of residual confounding.
- Patients with high magnesium intake through diet and supplements have a lower risk of progressing to type 2 diabetes.
- Patients with poor quality carbohydrate diets benefit more from high magnesium intake in that diabetes risk reduction is more distinct.
- Low nutritional diets insufficient in magnesium may predispose patients to diabetes.
Hruby A, Guasch-Ferre M, Bhupathiraju SN, et al. Magnesium Intake, Quality of Carbohydrates, and Risk of Type 2 Diabetes: Results From Three U.S. Cohorts. Diabetes Care. 2017; 40(11): 1-8.
Graciela Nieto, Pharm. D. Candidate 2018, LECOM School of Pharmacy