Obesity has escalated to pandemic levels, impacting over 650 million adults globally and significantly contributing to the burden of non-communicable diseases such as type 2 diabetes, cardiovascular disease, obstructive sleep apnea, non-alcoholic fatty liver disease, and infertility. The chronic, multifactorial nature of obesity presents substantial challenges for long-term management, as lifestyle modifications and pharmacotherapy often yield limited and transient success. In this context, Metabolic and bariatric surgery (MBS) has emerged as the most effective and enduring treatment for obesity, offering significant weight loss and marked improvement or remission of obesity-related comorbidities.
The most prevalent MBS procedures include sleeve gastrectomy (SG), Roux-en-Y gastric bypass (RYGB), and one-anastomosis gastric bypass (OAGB). While these interventions offer considerable metabolic advantages, they inherently cause significant modifications to gastrointestinal anatomy and physiology, which can predispose patients to long-term micronutrient deficiencies. These deficiencies can stem from reduced dietary intake, altered gastric acid secretion, decreased intrinsic factor production, and the bypassing of critical absorptive sites in the gastrointestinal tract. Commonly affected nutrients encompass iron, vitamin B12, Vitamin B6, folate, vitamin D, calcium, and zinc. If not effectively managed, these nutrient deficiencies can lead to anemia, secondary hyperparathyroidism, osteopenia, neurological complications, immune dysfunction, and impaired postoperative recovery.
Population-based recommended dietary allowances (RDAs) and tolerable upper intake levels (ULs) tend to underestimate the nutritional requirements for postoperative patients, as they are derived from healthy cohorts. Many standard formulations may fall short due to inadequate dosages, non-bioavailable forms, or poor tolerability, which can significantly impact patient adherence to supplementation regimens. Over-the-counter multivitamins, such as Centrum®, are designed for the general population and often lack the dosing, bioavailability, or elemental forms required for post-MBS physiology, particularly following bypass procedures.
The American Society for Metabolic and Bariatric Surgery (ASMBS) recommends 8-22 mg of elemental zinc per day, depending on the procedure, and the International Federation for the Surgery of Obesity and Metabolic Disorders (IFSO) and the World Gastroenterology Organization (WGO) recommend up to 30 mg/day for OAGB patients. These values are below the national upper limit in Egypt, which is 25 mg/day.
Moreover, there is evidence indicating a discrepancy in nutrient deficiencies among different bariatric surgery patients; for instance, OAGB patients exhibit a greater prevalence of iron and zinc deficiencies compared to those undergoing RYGB or SG, thereby necessitating proportionally higher supplementation tailored to their specific needs.
Aged 18 to 65 years
Capable of providing informed consent
Willing to comply with study procedures and follow-up visits over 12 months.
Candidates must have no prior history of MBS or gastrointestinal surgery and must be scheduled for one of the three aforementioned primary procedures.
The presence of chronic conditions that may independently affect micronutrient metabolism or absorption, such as chronic kidney disease, inflammatory bowel disease, or hepatic insufficiency.
Additional exclusion criteria include pregnancy or lactation at the time of enrollment
Plans for pregnancy within the study period
Active malignancy
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Treatment groupsSee each treatment group below.