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Obesity and Iron Deficiency

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Abstract

Iron deficiency is also called hypoferraemia, and was reported at first among people with obesity several hundred years ago. However, the correlation between iron deficiency and obesity remains uncertain or unclear. (According to who? Citation needed) The article, “Obesity and iron deficiency: a quantitative meta-analysis”, evaluates the presumed relationship or correlation between iron deficiency and obesity through assessment of concentration of haematological iron markets. The evaluation continues by assessing the iron deficiency in subjects with obesity (these include participants who are overweight) and non-overweight subjects (Zhao, Zhang, Shen, Fang, Wang, & Wang, 2015). In a secondary data collection move, the authors of the article performed systematic searches in renowned databases such as Embase and PubMed.

The articles researched through these websites have been published through December 2014. The study analyzed approximately 26 case-control and cross-sectional studies. These studies included 13, 393 obese individuals and 26, 621 in the overweight category (Zhao, Zhang, Shen, Fang, Wang, & Wang, 2015). The authors then compared the mean differences of blood iron markers and odds ratio of iron deficiency between obese and non-obese participants. The comparison was done using a random-effects model. The authors established that compared with non-obese subjects, the obese subjects had lower concentration of serum iron and lower percentages of transferring saturation (Manios, Moschonis, Papandreou, Politidou, Naoumi, Peppas, & Chrousos, 2015).

From these findings, the authors drew an important conclusion that obese subjects had a significantly increased risk of iron deficiency. In studies that did not involve ferritin-based diagnosis, the authors found an association between obesity and iron deficiency. Based on the ferritin-based diagnosis and related studies in that perspective, the authors concluded that obesity has a significant association with iron deficiency (Zhao, Zhang, Shen, Fang, Wang, & Wang, 2015). Therefore, the article recommends early treatment and monitoring of iron deficiency in obese and overweight individuals. Future research studies will help in testing whether the causal relationship exists between iron deficiency and obesity. (Delete abstract and start over. Too long and reads like an abstract for the article, not your paper. Focus on what your paper covers.)

Key words: obesity, iron, deficiency, ferritin, non-obese

Introduction

A presumed association or relationship between hypoferraemia and obesity was initially questioned more than 50 years ago. In 1961, lower levels of serum iron in overweight or obese subjects was measured, by Wenzel, and compared the results with non-obese or overweight subjects. Mayer and Seltzer supported these results (Zhao, Zhang, Shen, Fang, Wang, & Wang, 2015). Due to the epidemic increase in cases of obesity globally, numerous studies have been conducted on the subject, with a specific emphasis on examining the association between iron deficiency and obesity. Classic descriptions for iron deficiency among obese people include physical inactivity, inadequate dietary iron intake, and increased iron requirements. However recent research suggests that obesity-related iron-regulatory protein hepcidin and low grade inflammation play an important role in regulating endogenous iron homeostasis. (Citation needed)

An increased risk of development of iron deficiency has been demonstrated in obese children and adults, but other research studies indicate that this association is non-existent. There is, however, a lack of clarity in whether obesity impacts the risk of developing iron deficiency. Obese or overweight people who have iron deficiency have an increased health and well-being burden (Aigner, Feldman, & Datz, 2014). Starting with the depletion of iron, iron deficiency can progress to a condition called iron-deficient erythropoiesis, and then move to the serious part of iron deficiency anaemia. The researched and listed symptoms of anaemia include reduced exercise capacity, dyspnoea, fatigue, and weakness. In obese patients, these symptoms can be a hindrance to weight loss (Aigner, Feldman, & Datz, 2014). Additionally, the connection between anaemia and iron deficiency presents risks in increased mortality and heart failure.

Research design and method

The criteria for reporting and conducting meta-analysis of the observational studies have been done in previous studies. An independent literature analysis was conducted by two authors in PubMed and Embase databases. The articles used for the meta-analysis had been published through December 2014. Only English-written articles were used for the study.

The inclusion criteria included the following applications: studies that evaluated the relationship between obesity or overweight and iron status; studies that reported mean and standard deviation of these haematological iron markers; serum ferritin, serum iron, and transferrin saturation percentage; and studies that included both an obese and /or overweight group and a non-overweight. (This is word for word from the source – need to paraphrase and cite.) In the event of multiple research articles published using the same population, the authors selected the most informative articles, mostly the recent publications. The following diagnosis of obesity or overweight for adults was included by the study: Wetzel grid method (19) or body mass index (BMI); for adolescents and children, the following diagnosis of obesity or overweight was included: BMI Z-score, BMI-standard deviation score (BMI-SDS), BMI percentage adjusted for age and gender (Zhao, Zhang, Shen, Fang, Wang, & Wang, 2015).

The diagnosis was then followed with quantitative analytical methods for determining iron status using the following methods: flame atomic spectrometry or inductively coupled plasma mass spectrometry; serum iron was measured via a colorimetric assay; the measurement of serum ferritin was done using chemiluminescent immunometric assay, immunoradiometric assay or immunoturbidimetric assay. (Again, you need to paraphrase and cite – this comes straight from the source) The study then measured sTfR using particle-enhanced nephelometry and an enzyme-linked immunosorbent assay.

In analyzing the haematological iron markets, the sample mean and size with (standard deviation) of marker concentration in the obese or overweight group were compared with participants in the non-overweight group (Zhao, Zhang, Shen, Fang, Wang, & Wang, 2015). Weighted mean difference (WMD) method was used in calculating the effect size. The random effects model was used in assessing the effect size. Multivariate –adjusted risk estimates was used in analyzing the risk of IDA and ID. Group analyses were conducted stratified by sample size and study quality, ethnicity, geographic area, the analytical diagnosis for haematological iron markers or iron deficiency diagnosis methods, the method of weight diagnosis, overweight or obese, gender, and age.

Results and discussion

A total of 4,302 of potentially related research studies from Embase and PubMed, 212 articles were screened for evaluation (Zhao, Zhang, Shen, Fang, Wang, & Wang, 2015). Using the exclusion and inclusion criteria, a total of 26 original studies are meta-analyzed. Compared with non-obese or non-overweight groups, the TS% and serum iron concentration was significantly reduced or lower in the obese or overweight groups. The meta-analysis indicated a tendency towards higher serum ferritin levels, which is a major storage for iron protein (Aigner, Feldman, & Datz, 2014). The study showed the risk of developing iron deficiency to be higher in obese or overweight subjects.

The pooled OR was at 1.31, 95 percent confidence interval which indicated a close relationship between high body weight and iron deficiency (Zhao, Zhang, Shen, Fang, Wang, & Wang, 2015). For research, studies investigated the risk of developing iron deficiency anaemia among obese or overweight participants. Subgroup analyses were conducted both on iron deficiency risk stratified by relevant factors and haematological iron markers. In majority of the subgroups, the pooled effect size of the differences between the non-overweight groups and the obese or overweight groups remained significant for the three blood markers (Zhao, Zhang, Shen, Fang, Wang, & Wang, 2015).

Ethnicity, weight diagnostic methods, and age were all found to be meaningful stratified factors in the relationship analysis between the risk of developing iron deficiency and overweight or obesity. There were significant differences on subjects who were under 18 years and those past this age. The authors found high heterogeneity in the meta-analyses conducted. The heterogeneity was associated to the inherent differences in methodologies among the selected articles which included geographical location and sample selection strategy (Zhao, Zhang, Shen, Fang, Wang, & Wang, 2015). The study conducted a sensitivity analysis which indicated no evidence on the effect of individual study in the pooled results of the total effect sizes (Gartner, Berger, Bour, El Ati, Traissac, Landais, & Delpeuch, 2013).

The results of the study showed that the prevalence of iron deficiency is higher among obese and overweight populations compared with the non-obese populations. Since the diagnosis of iron deficiency is not well defined currently, interpreting relevant results gotten from different research groups can be difficult (Gartner, Berger, Bour, El Ati, Traissac, Landais, & Delpeuch, 2013). Obesity or overweight has an association with low-grade inflammation of WAT (white adipose tissue) due to chronic activation of the innate immune systems. Because of this relationship, patients with obesity-related iron deficiency may have elevated or normal levels of serum ferritin. The stratification analysis used between obese and overweight subjects detected a weight-dependent effect on the levels of iron. This is a regurgitation of the article not an analysis of the research methods used. What was the null hypothesis? Was the sample chosen well? Etc. What are the limitations, etc. You must provide an analysis in your paper not just an overview of the article. Review the assignment instructions and make sure you are addressing each component. How would you introduce this to the religious community? How would you propose to do this study? Etc.

Conclusion

The meta-analysis conducted by the authors provides strong evidence which support an association between obesity or overweight and iron deficiency. Therefore, it is important for obese and overweight people to undergo periodical screening for their status on iron, particularly given that some of these patients may already have a hidden iron deficiency or even the early stages of iron deficiency anaemia without laboratory findings and clinical changes (Aigner, Feldman, & Datz, 2014). Long term evaluation and monitoring of haematological iron markets is strongly needed and recommended, especially among adults in specific gender and or age categories for who a significant iron intake is of extreme importance, including women of childbearing age, adolescents and school-age children (Aigner, Feldman, & Datz, 2014).

More importantly, the methods used in diagnosing iron deficiency in obese and overweight individuals must be standardized. Since serum ferritin is not a sufficient sensitive index in the diagnosis of iron deficiency in overweight and obese patients, the use of ferritin should be avoided when diagnosing iron deficiency in overweight and /or obese individuals. There is need for future studies in testing presumed causal relationship between iron deficiency and obesity.

References

Aigner, E., Feldman, A., & Datz, C. (2014). Obesity as an emerging risk factor for iron deficiency. Nutrients, 6(9), 3587-3600.

Gartner, A., Berger, J., Bour, A., El Ati, J., Traissac, P., Landais, E., ... & Delpeuch, F. (2013). Assessment of iron deficiency in the context of the obesity epidemic: importance of correcting serum ferritin concentrations for inflammation. The American journal of clinical nutrition, 98(3), 821-826.

Manios, Y., Moschonis, G., Papandreou, C., Politidou, E., Naoumi, A., Peppas, D., ... & Chrousos, G. P. (2015). Revised Healthy Lifestyle‐Diet Index and associations with obesity and iron deficiency in schoolchildren: The Healthy Growth Study. Journal of Human Nutrition and Dietetics, 28(s2), 50-58.

Zhao, L., Zhang, X., Shen, Y., Fang, X., Wang, Y., & Wang, F. (2015). Obesity and iron deficiency: a quantitative meta‐analysis. Obesity Reviews, 16(12), 1081-1093