|Year : 2022 | Volume
| Issue : 2 | Page : 97-104
An evaluation of micronutrient status in severe obesity and follow-up assessment after bariatric surgery: A retrospective single-center study
Saba Amin Khan1, Astha Sachan1, Prasanna Ramana Arumugaswamy2, Archna Singh1, Sandeep Aggarwal2, Rakhee Yadav1
1 Department of Biochemistry, All India Institute of Medical Sciences, New Delhi, India
2 Department of Surgical Disciplines, All India Institute of Medical Sciences, New Delhi, India
|Date of Submission||02-Jul-2022|
|Date of Acceptance||19-Aug-2022|
|Date of Web Publication||21-Sep-2022|
Dr. Rakhee Yadav
Department of Biochemistry, All India Institute of Medical Sciences, New Delhi - 110 029
Source of Support: None, Conflict of Interest: None
Background: Micronutrient deficiency is common in obesity despite surplus weight and high caloric intake. Further exacerbation is often seen after bariatric surgery due to the resultant dietary restrictions, and physiological and anatomical alterations. Owing to the rising prevalence of obesity in India with a simultaneous surge in bariatric surgeries, an account of micronutrient status is required. This will help in identifying susceptible individuals and setting up priorities for prevention and intervention. Subjects and Methods: A retrospective study was designed to analyze the data collected before and until 1 year (3, 6, and 12 months) after bariatric surgery in individuals with severe obesity (body mass index ≥35 kg/m2, n = 150). We included the assessment of nutritional parameters, namely, serum iron, ferritin, total iron-binding capacity, Vitamin B12, folic acid, homocysteine, calcium, phosphorus, Vitamin D, and parathormone along with anthropometric and routine biochemical investigations. Results: Deficiency of Vitamin D was most prevalent (52%) at baseline, followed by anemia (21%). Ferritin deficiency was 9.3%, followed by iron (8.0%), Vitamin B12(7.3%), and folate deficiency (4.7%) at baseline. There was a remarkable improvement in Vitamin D deficiency (26%), whereas the percent prevalence of other micronutrients has shown deterioration in 12 months after bariatric surgery. No significant difference existed in the prevalence of micronutrient deficiency between laparoscopic sleeve gastrectomy (n = 75) and laparoscopic Roux-en-Y gastric bypass surgery (n = 75) over the 12-month follow-up period. Conclusion: Micronutrient deficiencies persisted after bariatric surgery underlining the need for fine adjustment of supplementations and monitoring compliance to ensure the best patient outcomes.
Keywords: Bariatric surgery, micronutrients, obesity, Vitamins
|How to cite this article:|
Khan SA, Sachan A, Arumugaswamy PR, Singh A, Aggarwal S, Yadav R. An evaluation of micronutrient status in severe obesity and follow-up assessment after bariatric surgery: A retrospective single-center study. J Bariatr Surg 2022;1:97-104
|How to cite this URL:|
Khan SA, Sachan A, Arumugaswamy PR, Singh A, Aggarwal S, Yadav R. An evaluation of micronutrient status in severe obesity and follow-up assessment after bariatric surgery: A retrospective single-center study. J Bariatr Surg [serial online] 2022 [cited 2022 Dec 4];1:97-104. Available from: http://www.jbsonline.org/text.asp?2022/1/2/97/356578
| Introduction|| |
The pandemic of obesity has caused a mounting burden on health-care systems across nations. The Global Burden of Disease Study (2017) emphasized the adverse impact of obesity on health outcomes stating that overweight/obesity has been the cause of 7.2% of the overall mortality. In India, the National Family Health Survey India-4 (2015–2016) characteristically revealed a surge in the prevalence of obesity which is more pronounced in urban settings, sometimes as high as 43%–44%, and especially in young adults.
Despite being considered a disease of surplus, obesity often co-exists with micronutrient deficiency. Although undetermined, several plausible reasons have been put forth such as the consumption of energy-dense, nutritionally depleted, and ultra-processed food. Furthermore, excess adipose tissue deposition hampers the bioavailability, synthesis, and metabolism of several minerals and vitamins. Additionally, antioxidant vitamin depletion becomes imminent with oxidative stress and the chronic inflammatory state of obesity.
To date, bariatric surgery has been the most successful, efficient, and long-term treatment option to manage weight loss and comorbidities associated with severe obesity. Evidence from the literature suggests that micronutrient deficiency is often a neglected long-term issue after bariatric surgery. Irrespective of the type of surgical procedure, postsurgical reduced gastric volume and alterations in gut anatomy become responsible for a shift in normal absorption of micronutrients as well as variation in the regulation of appetite, hunger, and satiety.
Yet, bariatric surgery as a treatment option is increasingly preferred over traditional weight loss programs in the past few years due to sustained weight loss. Currently, most bariatric surgeons follow the consolidated clinical recommendations endorsed by the American Society for Metabolic and Bariatric Surgery to optimize postoperative outcomes and improve the nutritional status of individuals undergoing bariatric surgery.
Data are scarce regarding micronutrient deficiencies in a setting of the rising prevalence of obesity with a subsequently increased number of bariatric surgeries performed in India. Since the Indian food culture, dietary habits, body type, and even obesity phenotype are significantly different from Western countries, it becomes imperative to establish evidence about the micronutrient status in our scenario. In 2015, the Center for Obesity and Digestive Surgery published putative nutritional recommendations for bariatric/metabolic surgeries specific to the Indian population based on population-based data collected from 2740 Indians with obesity. They provided data on common micronutrient deficiencies such as Iron, Vitamin B12, Calcium, and Vitamin D3 in a majority of Indians with obesity and asserted that robust supplementation is recommended.
However, there is paucity in the literature for such a revelation in the individual with severe obesity undergoing bariatric surgery. We have taken a retrospective analysis of the micronutrient status of such individuals at our Tertiary Care Center in the National Capital and focussed on describing the prevalence of deficiencies. Their trajectories after bariatric surgery were also followed at three different time points (3, 6, and 12 months). The analysis of most of the important parameters such as serum iron, ferritin, total iron-binding capacity (TIBC), Vitamin B12, folic acid, homocysteine, calcium, phosphorus, Vitamin D, and parathormone (PTH) at each time point of the study was comprehensively taken into account.
| Subjects and Methods|| |
Study design and setting
We designed a retrospective hospital-based study collaborating the Department of Biochemistry with the Department of Surgical Disciplines. We included the data of 150 participants (adults >18 years of age and body mass index [BMI] ≥35 kg/m2) who underwent bariatric surgery between the period of January 2018 and January 2020. The inclusion was to entail 75 individuals with obesity who underwent laparoscopic sleeve gastrectomy (LSG) and 75 others who underwent laparoscopic Roux-en-Y gastric bypass surgery (LRYGB). Those who were previously operated on or those whose data records were missing were excluded from the study.
Data were collected from hospital records for 10 micronutrient parameters for evaluation in our study. These parameters are part of the routine nutritional assessment done for those undergoing bariatric surgery. Serum levels of iron, ferritin, TIBC, Vitamin B12, folate, homocysteine, calcium, phosphorus, Vitamin D along with PTH, fasting plasma glucose, insulin, and glycated hemoglobin (HbA1c) were recorded before surgery (baseline) and at each of the three specific follow-up points, i.e., at 3, 6, and 12 months, respectively.
Surgical intervention-prerequisite and procedures
All surgeries were performed laparoscopically following the International Federation for the Surgery of Obesity and Metabolic Disorders-2011 guidelines. Individuals were selected for a bariatric surgical procedure if they had BMI ≥40 kg/m2 or BMI ≥35 kg/m2 along with any obesity-associated comorbidity. The type of surgical procedure was chosen considering BMI, comorbidity profile, liver function test, and the presence or absence of Gastroesophageal reflux disease. However, the final decision was taken only after discussing and ensuring that the individual had understood the advantages and disadvantages of the procedure. All procedures were performed by a single bariatric surgeon with experience of more than 15 years. Preoperatively, the individuals undergoing bariatric surgery were consulted with a team of dieticians/nutritionists, endocrinologists, surgeons, and psychologists. For such individuals who presented with micronutrient deficiencies at baseline, preoperative supplementations were prescribed based on serum levels of micronutrients, BMI, associated comorbidities, and date of the surgery.
Postoperative follow-up and supplementation
To prevent micronutrient deficiencies, which usually occur after bariatric surgery, the individuals undergoing surgery were prescribed vitamin supplementation regularly. All study participants were prescribed two tablets of commercially available fixed-dose Vitamin preparations per day. Each tablet contained iron: 11.25 mg, calcium: 300 mg, and Vitamin B12: 140 μg. In addition to this, participants were also given one iron tablet daily (45 mg), starting from 2 weeks of LRYGB. Furthermore, Vitamin B12 injections were given once weekly for 10 weeks, followed by once every 3 months for Vitamin B12 deficiency.
Bodyweight and height were measured using a digital scale with a precision of up to 300 g under standard conditions. BMI was calculated as per the formula weight in kilogram divided by squared of height in meters. Waist circumference (narrowest diameter between the xiphoid process and iliac crest) was taken to determine central obesity (abdominal obesity). Percentage total weight loss (%TWL) and percentage excess weight loss (%EWL) at each follow-up were calculated using following formulas: %TWL = (weight loss/preoperative weight) ×100 and %EWL= (weight loss/baseline excess weight) ×100 where weight loss = preoperative weight– weight at follow-up visit; baseline excess weight = preoperative weight-ideal weight. Ideal weight was calculated using an ideal BMI, as the ideal BMI cutoff point has been demonstrated to be 25 kg/m2.
Laboratory analysis-routine and micronutrient assessment
Standard laboratory protocols were followed for routine biochemical and micronutrient profile estimation, and the approved reference ranges were employed to determine the nutritional deficiency., Fasting serum samples were used to measure calcium and phosphorus with an automated analyzer (Beckman Coulter) as per manufacturer protocol. Serum Vitamin levels (Vitamin D, B12), as well as serum folate and Insulin, were estimated by an immunoassay-based electrochemiluminescent technique (Cobas-Roche diagnostic). Hemoglobin and serum Iron were estimated using the colorimetric method, while ferritin levels were measured by a latex-based immunoturbidimetric method. Serum HbA1c was determined using high-pressure liquid chromatography. Fasting Plasma Glucose was measured by the glucose oxidase-peroxidase method (Randox Laboratories, Crumlin, UK) according to the manufacturer's protocol.
To describe the demographic, anthropometric characteristics, and biochemical parameters of patients, the data were summarized and analyzed using Prism-GraphPad (GraphPad Software Inc, Version 8.0.1, San Diego, California, USA). Data was tested for normality using Shapiro–Wilk/Kolmogorov–Smirnov test. Continuous, parametric data were expressed as mean ± standard deviation of the mean (SD), and qualitative (categorical) variables were expressed in percentage. Paired Student's t-test was used to compare the normally distributed variables between study groups. The Chi-square test was used for comparing qualitative (categorical) data. A P < 0.05 was considered to represent a statistically significant difference between the groups.
| Results|| |
Clinical characteristics of the study participants
Baseline demographic characteristics are outlined in [Table 1]. The majority of participants were women (72%); men constituted 28% of the whole study group (n = 150) and the mean age of participants was 41.92 ± 9.95 years. Hypertension (58%) was identified as the most common associated comorbidity in our study, followed by Type-2 diabetes mellitus (51%).
|Table 1: Clinical characteristics of the study participants (n=150; body mass index ≥35)|
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Anthropometric profile of the study participants
The mean BMI of all the participants (n = 150) in our study at baseline was 47.9 ± 7.3 kg/m2, which got significantly reduced to 31.1 ± 5.0 kg/m2 in 12 months of follow-up after surgery. We also found significant changes in body weight, percentage % TWL, and % EWL at 3-, 6-, and 12-month postsurgery as summarized in [Table 2]. Similarly when we divided our study participants based on the type of surgery they underwent, both the subgroups (LSG; n = 75 vs. LRYGB; n = 75), LRYGB showed significantly more weight loss at the initial 3 months but later on followed similar trends and the differences were comparable at each time points of assessment after surgery.
|Table 2: Changes in anthropometric characteristics, biochemical parameters, and micronutrient profile of study subjects (n=150; body mass index ≥35) from baseline to 1 year of follow-up postoperatively|
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Biochemical parameters of the study participants
Baseline fasting plasma glucose, fasting insulin, and HbA1c were 113.0 ± 20.6 mg/dL, 20.2 ± 9.2 μU/L, and 6.5 ± 1.5, respectively, which significantly reduced to 94.5 ± 11.2 mg/dL, 10.7 ± 8.1 μU/L, and 5.7 ± 0.6, respectively, in 12 months after surgery in all participants (n = 150). A significant improvement (P < 0.001) was found in insulin response just 3 months after surgery.
Micronutrient status of the study participants
[Table 2] shows the mean value (with SD) of all selected micronutrient parameters for the whole study group (n = 150), while the percentage prevalence of their deficiency based on respective cutoffs is shown in [Table 3].
|Table 3: Percentage prevalence (%) of micronutrient deficiency in study subjects (n=150; body mass index≥35) from baseline to 1 year of follow-up postoperatively|
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Vitamin D was the most common deficiency at baseline with 52% of all the participants having Vitamin D <20 ng/mL. However, this percent prevalence went down to 26% at 12 months postsurgery. A significant increase in the mean value of Vitamin D from 22.8 ± 11.1 ng/mL to 29.1 ± 10.8 ng/mL; (P < 0.001) in 12 months after surgery was seen. We found elevated levels of serum PTH (70.6 ± 18.3 pg/mL) at a baseline, which reduced significantly over 12 months postoperatively (60.2 ± 11.3 pg/mL).
The mean value of hemoglobin at baseline for all the study participants (n = 150) was 12.9 ± 1.3 g/dL which lies within the normal range, however, a significant difference existed between genders (female 12.4 ± 1.0 g/dL and male 14.2 ± 1.0 g/dL; P < 0.05). Preoperative mean serum iron, serum ferritin, and TIBC were 65.0 ± 24.2, 55.7 ± 39.8, and 339.0 ± 69 μg/dL, respectively, which significantly reduced to 57.6 ± 23.4 μg/dL (P < 0.001), 54.6 ± 22.0 μg/dL (P < 0.001), and 357.0 ± 73 μg/dL (P < 0.05) in 12 months after surgery. It reflects that hemoglobin and iron profile deteriorated significantly in 12 months after bariatric surgery regardless of the type of surgical procedure used [Table 4]. Similarly, the mean value of serum Vitamin B12, serum folic acid, and serum homocysteine was also reduced 12 months after surgery.
|Table 4: Comparison of micronutrient profile between the two sub-groups based on the type of surgical procedure performed, i.e., Laparoscopic sleeve gastrectomy (n=75) and laparoscopic Roux-en-Y gastric bypass (n=75) from baseline to 1 year of follow-up postoperatively|
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[Table 4] shows comprehensive data for two surgical subgroups, i.e., LSG (n = 75) and LRYGB (n = 75) concerning all the measured biochemical and micronutrient parameters. Although significantly more weight loss was noticed in the LRYGB group at 3 months (P < 0.05) of follow-up, at the end of 1 year both the groups had a similar outcome. Barring serum calcium, phosphorus, and PTH, both the groups were comparable for micronutrient status, and no significant difference existed in the prevalence of micronutrient deficiency between them at various time-point over a 12-month follow-up period.
| Discussion|| |
Bariatric surgery is the most efficacious option available today to manage obesity on a long-term basis. According to the Obesity Surgery Society of India, the number of bariatric surgeries performed has increased nearly 100 times between 2004 and 2019; with around 20,242 bariatric surgeries performed in 2018 in India. Surgical treatment results in a significant decline in mortality and morbidity in individuals with obesity. However, there is always a risk of developing nutritional deficiencies because complications of this surgery have often been neglected.
In our analysis, where a significant reduction in weight and an improvement in associated comorbidities were seen, a trend of persistent micronutrient deficiencies following both LSG and LRYGB was observed. Several studies have shown more pronounced nutritional deficiency after LRYGB which is understandable because in this type of surgery the whole duodenum and proximal jejunum are bypassed resulting in malabsorption of several nutrients., However, there had been contrary reports where no significant difference in nutritional deficiencies between LSG and LRYGB was observed. Thus, a more complex phenomenon must be an underlying player rather than just an anatomical alteration that needs to be addressed. A change in the local gut hormonal as well as neuronal regulation and transformation of the gut microbiome are emerging as prominent mechanisms in developing micronutrient deficiency after bariatric surgery.
The analysis of our data for micronutrients at the baseline level revealed multiple micronutrient deficiencies in individuals with obesity undergoing bariatric surgery. The most common deficiency was Vitamin D in 52% of study participants, followed by anemia in 21%. A similar trend in the prevalence of several micronutrient deficiencies at baseline was observed by Lefebvre et al., and Johnson et al., in their studies, respectively.,
Vitamin D deficiency is not uncommon at baseline in the majority of individuals with obesity undergoing surgery. In fact, in a meta-analysis of 51 observational studies, 29 studies showed mean baseline Vitamin D levels below 30 ng/ml and the other 17 studies had levels ≤20 ng/ml. In most of these studies, the level of Vitamin D remained below 30 ng/ml after bariatric surgery despite various Vitamin D replacement regimens, followed by centers. An improvement in the levels of Vitamin D from 22.8 ± 11.1 ng/dL (at baseline) to 29.1 ± 10.8 9 (at 1 year postoperatively) in our study can be attributed to an appropriate and calibrated dosage of Vitamin D supplementation and probably, with considerable weight loss after surgery, the stored Vitamin D was released resulting in increased serum levels. Moreover, it is postulated that Vitamin D gets sequestered in adipose tissue reducing bioavailability, and also, some potential inhibitory effects of high levels of leptin and interleukin-6 on Vitamin D synthesis are observed in obesity.
Vitamin D plays a key role in bone metabolism by regulating Calcium homeostasis and directly or indirectly modulating PTH levels. Vitamin D deficiency leads to raised levels of serum PTH. In our study also, secondary hyperparathyroidism was found in 40% of our study participants at baseline which came down to 14% at 12 months postoperatively. Several studies have attributed an independent association between high serum levels of PTH and BMI and an increased risk of metabolic syndrome. Nevertheless, serum calcium and phosphorus levels remained within the normal range at baseline as well as after bariatric surgery in our study.
The evaluation of the iron profile in our study incorporated an assessment of serum Iron, Ferritin, and TIBC. About 21% of our participants had low hemoglobin, which increased to 33% in 12 months after surgery. About 72% of these participants were women mostly in the reproductive age group who have a higher risk of developing iron deficiency. Individuals undergoing bariatric surgery for obesity are often at dual risk of developing anemia of chronic disease as well as anemia due to iron deficiency. The percentage prevalence of iron deficiency was 12.8% before surgery which increased to 20.6% after a year of surgery. This trend corroborated with many of the previous studies where the prevalence of iron deficiency after bariatric surgery was estimated to vary from 30% to 60%. Anemia is widespread in the Indian population, recent data show that the prevalence of anemia in Indian women aged 15–49 years is 53%, and 23% of Indian men aged 15–49 years are anemic. The root of this problem lies in our inapt dietary patterns, which are low in iron content and has components that are known to interfere with the bioavailability of Iron. This further gets aggravated in obesity due to a chronic low-grade inflammatory state which affects the systemic iron levels. Such individuals have an increased level of acute-phase proteins and pro-inflammatory cytokines which trigger the release of hepcidin, a systemic regulator of iron homeostasis. Thus, both iron absorption and mobilization of stored iron are affected, resulting in iron deficiency anemia. An important indicator of the body's iron stores is Ferritin, the percentage prevalence of whose deficiency in our study was 9.3% at baseline and increased to 16.7% at 12 months postoperatively. A similar picture of worsening in ferritin levels has been described by Ferraz et al. in their studies on individuals undergoing bariatric surgery. Ferritin being an acute phase reactant itself is increased in inflammatory conditions; therefore, it cannot reflect the accurate picture of iron deficiency in a disparate setting witnessed in obesity. When we compared the iron profile between the two groups of surgeries, we did not find any significant difference. This was contrary to our expectations because Krzizek et al. in a study on 1216 participants concluded that SG has a lower rate of anemia with iron and ferritin deficiency compared to RYGB as the main sites of iron absorption (the duodenum and proximal jejunum) are bypassed. However, a metanalysis by Kwon et al. suggested that there is no significant difference between the two groups of surgery with respect to iron deficiency anemia.
The status of another important hemopoietic micronutrient; Vitamin B12, revealed a drop from the levels of 291.7 ± 88.4 to 283.0 ± 97.8 in 1 year after surgery. Vitamin B12 is a common nutritional deficiency in individuals with obesity undergoing bariatric surgery. A metanalysis by Nunes et al. showed that Vitamin B12 deficiency gets exacerbated after bariatric surgery, especially after RYGB. However, no significant difference between LSG and LRYGB with regard to Vitamin B12 deficiency was observed in our study which was similar to what Moizé et al. concluded in the comparative study on nutritional deficiencies following SG and RYGB. Postoperative Vitamin B12 deficiency is due to the decreased secretion of intrinsic factor resulting from loss of parietal cells in gastric mucosa and decreased gastric acidity, which is essentially required to release the protein-bound form of Vitamin B12. Folate deficiency is not commonly reported in most studies, considering that it can be absorbed in most parts of the gastrointestinal tract. Nevertheless, its optimal level is required for proper cell growth and division, methylation, neurodevelopment, and reproductive and cardiovascular health. According to some investigations, the presence of folate deficiency mostly indicates noncompliance to multivitamin supplementation. This might be one of the reasons as we also found reduced folate levels 12 months after surgery.
An important compound closely related to both Vitamin B12 and folate is homocysteine, as their metabolisms are interlinked. The deficiency of Vitamin B12 and folate reflects the variation in levels of homocysteine. We found that significantly elevated levels of serum homocysteine following surgery were negatively correlated with both Vitamins. Hyperhomocysteinemia is known to be an independent predictor of cardiovascular risk. Where, bariatric surgery endorses an amelioration of the cardiovascular comorbidities in obesity, the presence of hyperhomocysteinemia revokes such effects. This paradoxical scenario needs attention and it has been suggested that despite routine multivitamin supplementation if the level of homocysteine remains elevated, it is worth considering the administration of methylated form of folic acid and Vitamin B12.
Despite an extensive search, we could not find many reports on the Indian population addressing the issue of micronutrient deficiency in individuals with obesity undergoing bariatric surgery. Only recently Misra et al. showed a worsening of multiple micronutrient deficiencies after bariatric surgery. This data pertain to south India which when compared with the north Indian population, has distinctive dietary and lifestyle patterns. Besides, such a comprehensive account of 10 micronutrients has not been put forth yet.
The analysis of our data showed a higher percentage prevalence of vitamin and micronutrient deficiency both at the pre- and post-operative stage, indicating that the supplementation dosage followed currently should be closely monitored and finely adjusted to manage the individual nutritional requirements.
Limitation of the study
Owing to the retrospective nature of our study, we could not take into consideration the actual compliance of the individuals with prescribed supplementation, which become a major limitation of our analysis.
| Conclusion|| |
An important insight has been drawn into the fact that correction of preexisting nutritional deficiencies might be decisive in preventing postoperative micronutrient deficiencies. The status of such micronutrients must be followed up in the long term and adherence to the compliance of the prescription must be ensured to achieve a holistic outcome of bariatric surgery.
This research did not receive any specific grant from funding agencies in the public, commercial, or nonprofit sectors. We would like to thank all of the participants without whom this study would not have been possible.
Financial support and sponsorship
Department of Biochemistry and Department of Surgical Disciplines, All India Institute of Medical Sciences, New Delhi.
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2], [Table 3], [Table 4]