In this national population-based study conducted in Jordan in 2009, we demonstrated the prevalence of metabolic syndrome and its components among adults and their relation to low magnesium levels. We found alarmingly high prevalence rates of metabolic syndrome and its components as defined by IDF criteria. Indeed, more than one-third of all Jordanian adults met the criteria of metabolic syndrome (39.8%), with the highest burden being among women (40.7% in women and 37.4% in men). Among metabolic syndrome components, central obesity and low HDL were the most commonly occurring components of metabolic syndrome (62.6% and 65.5%, respectively). In fact, central obesity was more prevalent among women (66.5%), while low HDL was more prevalent among men (69.6%). These findings are consistent with the study conducted in Northern Jordan, using ATP definition, which reported a metabolic syndrome prevalence estimate of 36.3%, being higher in women than in men (40.9% and 28.7%, respectively). Furthermore, this study found that central obesity was the most common abnormality in women (69.1%), while low HDL was the most common abnormality in men (62.7%) (24). Interestingly, using IDF criteria, the prevalence of metabolic syndrome in Jordan was markedly higher in 2017 being 48.2% (52.9% in men and 46.2% in women) (25).
Our metabolic syndrome prevalence estimate was slightly higher than those reported in the US population from 2003–2012 (33.0%) (26) and Australian population (35.8%) (27). On the other hand, higher estimates were reported in Turkey (44.0%), Pakistan (63.7%), Tunisia (45.5%), and Emirates (48.7%) (28). The considerable variations in the prevalence rates of metabolic syndrome may be attributable to many factors, including the criteria of metabolic syndrome used, study design and sampling, the variations in age and gender structure of the population, and a combination of genetics and environmental factors.
Our results showed high rates of abdominal obesity (62.6%). This is in line with the studies conducted among the US and Greek population with abdominal obesity rates of 53% and 72%, respectively (29, 30). Interestingly, counties with high rates of metabolic syndrome demonstrated high rates of central obesity; Portugal (51.0%)(31), Turkey (56.8%)(32), Tunisia (69.5%)(33). consequently, the high prevalence of metabolic syndrome could be explained by the high prevalence of abdominal obesity. Obesity is a worldwide health problem being attributable to the increased risk of several diseases, including diabetes and cardiovascular diseases (34). It has been proposed that by 2030, obesity will reach levels of 89% and 85% in males and females, respectively (35). Therefore, the implementation of health care programs is strongly recommended to increase people’s awareness towards an adoption of a healthy lifestyle in the form of appropriate dietary habits and physical activity.
Magnesium deficiency may play an essential role in the development of metabolic syndrome. In line with this, our results revealed an independent relationship between metabolic syndrome and low serum magnesium levels. The inverse association found in the present study is supported by findings of various other studies (14–16, 36–40). Furthermore, studies have demonstrated that metabolic syndrome is less prevalent in subjects with higher levels of dietary magnesium intake (41–46). In this context, results from these studies support the hypothesis that low body magnesium status could be a potential risk factor for the development of metabolic syndrome. The present finding is not consistent, however, with the results from cross-sectional studies which revealed no association between serum magnesium and metabolic syndrome (17, 43). No association was also found between dietary magnesium intake and supplementation with metabolic syndrome in prospective and clinical randomized studies, respectively (47, 48). Additionally, hair magnesium concentration was shown to have no significant association with metabolic syndrome (19). The discrepancy between the results of the studies could be explained by differences in the sample size, variability in the characteristics of the study populations, and the geographical locations where there are differences in the lifestyle, dietary habits, and genetic phenotype among individuals. In fact, populations may have different responses to the same level of magnesium depending on the variations in genetic background (16). Interestingly, the use of different criteria for metabolic syndrome could affect the association. Indeed, a meta-analysis study found that the association was stronger in studies that used the NCEP-ATP III definition rather than the modified NCEP-ATP III, IDF, AHA/NHLBI, or WHO definitions (16). Furthermore, hair analysis is considered to be an unreliable tool for assessing trace elements and nutritional balance in individuals (49).
The relationship between serum magnesium levels and components of the metabolic syndrome is conflicting. Our study suggests an independent association between hypomagnesemia and decreased levels of HDL-cholesterol. Our finding is in agreement with the study conducted by Guerrero-Romero concluding that hypomagnesemia contributed to lower HDL (13). A case-control study of low serum magnesium level and lipid profile among patients with osteoarthritis, found that hypomagnesemia was related to decreased serum levels of HDL (p < 0.001) (50). Findings suggest that low serum magnesium levels could be incriminated in the pathogenesis of cardiovascular disease through alteration in the blood lipid composition in a way that predisposes to atherosclerosis (51). One possible explanation is that magnesium acts as a cofactor for a number of enzymes involved in lipid metabolism. Indeed, it has been postulated that magnesium intake may increase the activity of lipoprotein lipase, which is involved in the conversion of triglycerides to HDL-Cholesterol (52).
Our results revealed no significant association between low magnesium levels and central obesity. This finding is in accordance with the previous reports (53–55). In fact, it has been shown that middle-aged obese individuals can maintain normal circulating levels of magnesium, compared to type 2 diabetes and older subjects (56). We have also failed to demonstrate a cross-sectional relationship between low serum magnesium levels and hyperglycemia. Our results are supported by a 12-week clinical randomized study concluding that magnesium replacement in recommended dosage didn’t reduce insulin resistance (48). Finally, our study showed that individuals with hypertension had lower levels of serum magnesium with respect to those with normal blood pressure, but this association was no longer significant in multivariate analysis.
Although our study has the strength of being a national population-based study with a relatively large sample size, there are several limitations that deserve to be mentioned. First, since the study was cross-sectional in nature, a temporal relationship between hypomagnesemia and metabolic syndrome can’t be established, and thus we don’t know whether low magnesium concentration was a consequence of metabolic syndrome or a precipitating factor leading to its development. Second, the dietary intake of magnesium in relation to the prevalence of metabolic syndrome and its components was not assessed in the present study. Last but not least, we have used serum magnesium to indicate low magnesium status. It is important to highlight the fact that magnesium is chiefly an intracellular ion; therefore, serum magnesium is considered to be a poor indicator of body magnesium. However, serum magnesium is the most widely used measure of magnesium status in many studies to illustrate the relationship between magnesium and metabolic syndrome.
In conclusion, the prevalence of metabolic syndrome is considerably high in Jordan accounting for more than one-third of all Jordanian adults. Central obesity and low HDL were the most occurring components of metabolic syndrome. The increase in the prevalence of metabolic syndrome and its components is probably due to the adoption of westernized behaviors and sedentary life-style. Therefore, future policies and health education programs, aiming at encouraging people to adhere to the guidelines and recommendations of a healthy diet and physical activity, should be taken into consideration. Furthermore, the findings from the present study provide evidence that serum magnesium is inversely associated with the prevalence of metabolic syndrome. However, the data cannot support a causal role for hypomagnesemia in the development of metabolic syndrome because of the cross-sectional nature of the study.