Long-term effect of sleeve gastrectomy vs Roux-en-Y gastric bypass in people living with severe obesity: a phase III multicentre randomised controlled trial (SleeveBypass).

Background: Sleeve gastrectomy is the most performed metabolic surgical procedure worldwide. However, conflicting results offer no clear evidence about its long-term clinical comparability to Roux-en-Y gastric bypass. This study aims to determine their equivalent long-term weight loss effects. Methods: This randomised open-label controlled trial was conducted from 2012 until 2017 in two Dutch bariatric hospitals with a 5-year follow-up (last follow-up July 29th, 2022). Out of 4045 patients, 628 were eligible for metabolic surgery and were randomly assigned to sleeve gastrectomy or Roux-en-Y gastric bypass (intention-to-treat). The primary endpoint was weight loss, expressed by percentage excess body mass index (BMI) loss. The predefined clinically relevant equivalence margin was -13% to 13%. Secondary endpoints included percentage total kilograms weight loss, obesity-related comorbidities, quality of life, morbidity, and mortality. This trial is registered with Dutch Trial Register NTR4741: https://onderzoekmetmensen.nl/nl/trial/25900. Findings: 628 patients were randomised between sleeve gastrectomy (n = 312) and Roux-en-Y gastric bypass (n = 316) (mean age 43 [standard deviation (SD), 11] years; mean BMI 43.5 [SD, 4.7]; 81.8% women). Excess BMI loss at 5 years was 58.8% [95% CI, 55%-63%] after sleeve gastrectomy and 67.1% [95% CI, 63%-71%] after Roux-en-Y gastric bypass (difference 8.3% [95% CI, -12.5% to -4.0%]). This was within the predefined margin (P < 0.001). Total weight loss at 5 years was 22.5% [95% CI, 20.7%-24.3%] after sleeve gastrectomy and 26.0% [95% CI, 24.3%-27.8%] after Roux-en-Y gastric bypass (difference 3.5% [95% CI, -5.2% to -1.7%]). In both groups, obesity-related comorbidities significantly improved after 5 years. Dyslipidaemia improved more frequently after Roux-en-Y gastric bypass (83%, 54/65) compared to sleeve gastrectomy (62%, 44/71) (P = 0.006). De novo gastro-oesophageal reflux disease occurred more frequently after sleeve gastrectomy (16%, 46/288) vs Roux-en-Y gastric bypass (4%, 10/280) (P < 0.001). Minor complications were more frequent after Roux-en-Y gastric bypass (5%, 15/316) compared to sleeve gastrectomy (2%, 5/312). No statistically significant differences in major complications and health-related quality of life were encountered. Interpretation: In people living with obesity grades 2 and 3, sleeve gastrectomy and Roux-en-Y gastric bypass had clinically comparable excess BMI loss according to the predefined definition for equivalence. However, Roux-en-Y gastric bypass showed significantly higher total weight loss and significant advantages in secondary outcomes, including dyslipidaemia and GERD, yet at a higher rate of minor complications. Major complications, other comorbidities, and overall HRQoL did not significantly differ between the groups. Funding: Not applicable.

Factors Affecting Patient Adherence to Multivitamin Intake After Bariatric Surgery: Thematic Analysis of Qualitative Data From a Multicenter Study.

Introduction Adherence to daily intake of multivitamin supplementation (MVS) is a major challenge after bariatric surgery (BS). The aim of this study was to identify insights into patients' beliefs and experiences on adherence to MVS intake. Methods A thematic analysis of qualitative data from four high-volume bariatric centers in the Netherlands was conducted. A series of texts from the open-ended question of 1,246 patients were thematically analyzed for common or overarching themes, ideas, and patterns. Results Five key themes emerged regarding participants' suggestions on adherence to daily MVS intake: "gastrointestinal side effects to MVS intake" (n = 850, 68.2%), "negative features of MVS" (n = 296, 23.8%), "satisfaction with advice on MVS" (n = 272, 21.8%), "dissatisfaction with service provision" (n = 160, 12.8%), and "costs" (n = 93, 7.5%). Most problems were experienced when using specialized weight loss surgery (WLS) MVS. These supplements may cause gastrointestinal side effects, and costs are too high. After bariatric surgery, numerous patients strongly felt that information provision was poor in several aspects, and the aftercare pathway process did not provide sufficient support. Conclusion This study found five major themes involved in patient adherence to multivitamin intake after BS: gastrointestinal side effects to MVS intake, negative features of MVS, satisfaction with advice on MVS, dissatisfaction with service provision, and costs of specialized MVS. Challenges lie in stronger education for both patients and healthcare professionals. More personalized care could probably increase patient satisfaction, and MVS companies should look at further optimizing supplements for better tolerability and reducing costs.

Factors Affecting Patient Adherence to Multivitamin Intake After Bariatric Surgery: a Multicentre Survey Study from the Patient's Perspective.

PURPOSE: Lifelong multivitamin supplementation is recommended to prevent nutritional deficiencies. Despite this advice, deficiencies are common which may be due to poor adherence to MVS intake. The aim of this study was to identify which factors affect patient adherence to Multivitamin Supplement (MVS) intake after bariatric surgery. MATERIALS AND METHODS: A 42-item questionnaire was sent to 15,424 patients from four Dutch bariatric center. In total, 4975 patients wanted to participate of which 361 patients were excluded. A total of 4614 patients were included, and MVS users (n=4274, 92.6%) were compared to non-users (n=340, 7.4%). Most patients underwent Roux-en-Y gastric bypass (64.3%) or sleeve gastrectomy (32.3%). RESULTS: Seven hundred and ten patients (15.4%) reported inconsistent MVS use and 340 patients (7.4%) did not use any MVS at all. For inconsistent MVS users, most reported reasons included forgetting daily intake (68.3%), gastro-intestinal side effects (25.6%) and unpleasant taste or smell (22.7%), whereas for non-users gastro-intestinal side effects (58.5%), high costs (13.5%) and the absence of vitamin deficiencies (20.9%) were most frequently reported. Overall, 28.5% were dissatisfied about instructions on MVS use, attention paid to MVS use during medical consultation and the extent to which personal preferences were taken into account. CONCLUSION: The attitude of bariatric patients towards MVS use is predominantly negative. It is important to provide accurate information on different options for MVS intake and collect information about patient's personal preferences when prescribing supplements. Improving adherence to MVS intake is challenging and requires implementation of a shared decision-making process, further optimization of MVS formulas and exploring options for reimbursement.

The Influence of Different Alimentary and Biliopancreatic Limb Lengths in Gastric Bypass Patients.

PURPOSE: The aim of this study was to compare the effect of two different limb lengths after RYGB on weight loss, postoperative gastro-intestinal complications, and vitamin deficiencies. MATERIALS AND METHODS: A retrospective analyses of 100 patients after RYGB with 2 different limb lengths were done. Group A (50 patients) had a biliopancreatic limb (BPL) of 75 cm and an alimentary limb (AL) of 150 cm. Group B (50 patients) had a BPL of 150 cm and an AL of 75 cm. The effect on weight loss, body mass index, excess weight loss (EWL), total weight loss (TWL), and postoperative complications was analyzed up to 2 years postoperatively. RESULTS: Patients with a longer BPL achieved significantly more %EWL compared to a shorter BPL 2 years postoperatively (82.8 ± 31.2 versus 93.8 ± 15.1; p = 0.038). A significant difference was also seen in %TWL after 1 year (30.3 ± 10.1 versus 37.4 ± 6.9; p < 0.01) and 2 years (31.6 ± 7.5 versus 35.6 ± 8.6; p = 0.022), both in favor of group B. However, patients with a longer BPL (group B) showed significant more diarrhea and steatorrhea compared to group A (p < 0.01). CONCLUSION: BPL of 150 cm is associated with more %EWL and %TWL 2 years after RYGB. However, it is accompanied by an increase of diarrhea and steatorrhea to disadvantage off group B. Future studies need to focus on further tailoring BPL and AL lengths to achieve the best possible outcomes for patients with morbid obesity.

The Prognostic Value of the Dutch Sweet Eating Questionnaire on Weight Loss After Metabolic Surgery: a Randomized Controlled Trial.

BACKGROUND: Laparoscopic Roux-en-Y gastric bypass (LRYGB) and laparoscopic sleeve gastrectomy (LSG) have shown different weight loss results. These differences might be partly due to dumping after LRYGB, forcing sweet eaters to switch to a healthy diet. The Dutch Sweet Eating Questionnaire (DSEQ) is validated to measure sweet eating. This study aims to investigate if sweet eating measured with the DSEQ influences weight loss. METHODS: In this multicenter randomized controlled trial, patients were included between 2013 and 2017 in two Dutch high-volume hospitals, and randomized with a 1:1 ratio between LRYGB and LSG. Primary outcome measure was weight loss. Secondary outcome measure was sweet eating behavior, measured with the DSEQ. Data was collected at baseline, 1 year and 2 years postoperatively. RESULTS: Data was analyzed of 623 patients who underwent LRYGB (n = 308; 49.4%) or LSG (n = 315; 50.6%). Follow-up rates at 2 years postoperative were 67.1% for weight and 35.3% for DSEQ. At 2 years postoperative, mean BMI was significantly higher after LSG than LRYGB (respectively 30.88 versus 28.87 kg/m2, p < 0.001), and the percentage of sweet eaters was significantly higher after LSG than LRYGB (respectively 8.6% versus 2.6%, p = 0.049). None of the preoperative sweet eaters were sweet eaters 2 years after LRYGB (0.0%), versus 11.8% 2 years after LSG. No correlation was found between postoperative sweet eating behavior and %EBMIL. CONCLUSION: No significant correlation was found between preoperative or postoperative sweet eating measured with the DSEQ and weight loss. The decision-making for the procedure type is more complex than weight loss and dietary habits, and should also involve quality of life and presence of comorbidities. These factors should be addressed in future research along with longer term results. TRIAL REGISTRATION: Dutch Trial Register NTR-4741.

Matched Short-Term Results of SADI Versus GBP After Sleeve Gastrectomy.

BACKGROUND: The gastric bypass (GBP) is the most popular revisional technique after sleeve gastrectomy (SG). However, the results after revision are not always satisfactory in terms of additional weight loss and complications. The single anastomosis duodenoileal bypass (SADI) could be a valuable alternative. OBJECTIVE: This study is a retrospective matched-control study reviewing short-term results in terms of weight loss and comorbidities reduction of both SADI and GBP as a revisional procedure after primary sleeve gastrectomy. Complications and vitamin deficiencies will be evaluated as well. METHODS: Patients with a SADI procedure after a primary sleeve gastrectomy (SG) with a minimum follow-up of 1 year were included. Their results were retrospectively reviewed and matched with a cohort of GBP patient on age, BMI, and gender. Comparison was on comorbidities, weight loss, complications, and blood markers. RESULTS: A total of 64 patients were included, 32 SADI procedures and 32 matched gastric bypasses with no significant differences on baseline. No differences were found in terms of (additional) total weight loss. The operating time of the SADI was significantly longer (p = 0.007). No clinically relevant differences were found concerning comorbidities or blood markers. In the SADI group, more defecation problems were reported and fewer vitamin deficiencies were encountered. CONCLUSION: Based on a small group and short-term results, the SADI could be regarded as a safe alternative to a GBP following SG with a similar amount of additional weight loss and fewer post-operative early complications. Longer follow-up and larger studies are needed to determine its full potential.

Neuropathy by folic acid supplementation in a patient with anaemia and an untreated cobalamin deficiency: a case report.

The rising rates of bariatric surgery (BS) are accompanied by neurological complications related to nutrient deficiencies. One of the risk factors for neurological complications in BS patients is poor vitamin and mineral supplementation. Prevention, diagnosis and treatment of these disorders are necessary parts of lifelong care after BS. Particularly important for optimal functioning of the nervous system are vitamin B1 , B6 , B12 (cobalamin), E, copper and possibly vitamin B11 (folic acid). In this case report, we narrate about a patient with anaemia and multiple vitamin and mineral deficiencies after Roux-en-Y gastric bypass (RYGB) with an alimentary limb of 150 cm and a biliopancreatic limb of 100 cm. RYGB is associated with an increased risk of vitamin deficiencies, especially a vitamin B12 deficiency. The patient in this case report developed psychiatric-neurological symptoms due to folic acid supplementation in an untreated cobalamin deficiency. Second, we tried to elucidate the vitamin physiology to understand specific mechanisms after BS.

Lipoedema in patients after bariatric surgery: report of two cases and review of literature.

Lipoedema is a disorder of adipose tissue that is characterized by abnormal subcutaneous fat deposition, leading to swelling and enlargement of the lower limbs as well as the trunk. This entity is often misdiagnosed as lymphoedema or obesity and, therefore, may be overlooked and missed in patients scheduled for bariatric surgery. Patients with lipoedema who undergo bariatric surgery may have to continue to have extensive lower extremity and trunk adiposity despite adequate weight loss. In this report, we present two patients who had extensive trunk and lower extremity adiposity, one of them before and the other after the bariatric surgery.

Quality of life after Nissen fundoplication in patients with gastroesophageal reflux disease: Comparison between long- and short-term follow-up.

INTRODUCTION:: Nissen fundoplication is the golden standard for surgical treatment of gastroesophageal reflux disease (GERD). Numerous studies report excellent short-term results. However, data regarding long-term quality of life are lacking. The aim of this study is to investigate the long-term quality of life after Nissen fundoplication in patients with GERD and to compare this with the short-term results. PATIENTS AND METHODS: We retrospectively analysed all patients who underwent laparoscopic Nissen fundoplication for GERD between January 2004 and January 2016. All patients received a validated GERD-Health-Related Quality of Life questionnaire by mail to assess post-operative quality of life. Maximum quality of life is represented by a score of 75. Secondary outcome measures were complications and recurrence rate. RESULTS:: One hundred and seventy-five (77.1%) of the 227 operated patients returned the questionnaire. The median follow-up was 3.7 (0.1-10.3) years. Mean age was 51.6 (range 15-85) and 72 patients were male. We report an excellent quality of life with a median total score of 70 (range 2-75). Re-operation rate was 13.6% (23/169); the re-operation was due to recurrent reflux in 12 patients and due to persistent dysphagia in 11 patients. 91.3% of the re-operations were performed within the first 5 years after surgery. Mortality rate was zero. CONCLUSION:: We report a large series of single-centre, single-surgeon laparoscopic Nissen fundoplication. Despite the re-operation rate of 13.6%, we found excellent long-term symptomatic outcome. There was no difference between short- and long-term results.

A collective review of biological versus synthetic mesh-reinforced cruroplasty during laparoscopic Nissen fundoplication.

BACKGROUND: Laparoscopic cruroplasty and fundoplication have become the gold standard in the treatment of hiatal hernia and gastro-oesophageal reflux disease (GERD). The use of a mesh-reinforcement of the cruroplasty has been proven effective; although, there is a lack of evidence considering which type of mesh is superior. The aim of this study was to compare recurrence rates after mesh reinforced cruroplasty using biological versus synthetic meshes. METHODS: We performed a systematic review of all clinical trials published between January 2004 and September 2015 describing the application of a mesh in the hiatal hernia repair during Nissen fundoplication for both GERD and hiatal hernia. The primary outcome was the recurrence rate, and secondary outcomes were complication rate, mortality and symptomatic outcome. RESULTS: We included 16 studies and extracted data regarding 1089 mesh operated patients of whom 385 received a biological mesh and 704 a synthetic mesh. The mean follow-up was 53.4 months. The recurrence rate in the synthetic mesh group was 6.8% compared to 16.1% in the biological mesh group (P < 0.05). The complication rate was 5.1% and 4.6% (P = 0.694), respectively, and there were 12 mesh-related complications. No mesh-related mortality was reported. CONCLUSION: Mesh reinforcement of hiatal hernia repair seems safe in the short-term follow-up. The available literature suggests no clear advantage of biological over synthetic meshes. Regarding cost-efficiency and short-term results, the use of synthetic nonabsorbable meshes might be advocated.

The safety and efficiency of a fast-track protocol for sleeve gastrectomy: a team approach.

BACKGROUND: Increasing numbers of morbid obese patients has led to increased numbers of bariatric procedures. Fast-track protocols are being developed to enhance the available resources, while maintaining a safe procedure. Reported results on safety merely apply to a mixed bariatric population. The objective was to evaluate safety and efficiency of the fast-track principles in patients undergoing sleeve gastrectomy. METHODS: Retrospective observational study including patients undergoing primary sleeve gastrectomy at the Obesity Centre of the Catharina Hospital Eindhoven, the Netherlands. Conventional perioperative care (CC) (2008-2011) versus a fast-track protocol (FT) (2011-2013), using short-acting anesthetic agents, a multi-modal pain protocol to reduce opioids, and early mobilization. The main parameters for safety were intraoperative, early and late postoperative complications. Procedure time and hospital stay were used to evaluate efficiency. RESULTS: This study included 805 patients, 494 patients were subjected to the conventional care and 318 patients to fast-track protocol. A reduction of median operation time from 60 (CC) to 40 minutes (FT) (P<0.001) and a reduction in median length of hospital stay from three to two days (P=0.001), with a significant reduction in early postoperative complications (9.9% [CC] vs. 5% [FT], P=0.016) was achieved. The amount of late complications was comparable for both groups (5.1% [CC] vs. 4.4% [FT] [P=0.738]). CONCLUSIONS: Implementation of a fast-track protocol for sleeve gastrectomy is safe and efficient. It effectively reduces operation time and length of hospital stay, while improving postoperative outcome. This pleads for standard implementation of the fast-track protocol in sleeve gastrectomy.

Improved and more effective algorithms to screen for nutrient deficiencies after bariatric surgery.

BACKGROUND/OBJECTIVES: Most bariatric guidelines recommend frequent lab monitoring of patients to detect nutrient and vitamin deficiencies as early as possible. The aim of this study was to optimize the cost effectiveness of the nutrient panel, by developing an algorithm, which detects nutrient deficiencies at lower costs. SUBJECTS/METHODS: In this retrospective study, 2055 patients who had undergone Laparoscopic Roux-Y Gastric Bypass (LRYGB) and Laparoscopic Sleeve Gastrectomy (LSG) surgery at Catharina Hospital Eindhoven between January 2009 and December 2013 were included. Perioperative biochemical measurements (7 days before and 127 days after surgery) and measurements >549 days before surgery were excluded. For analysis, the most recent preoperative and postoperative measurements were selected for each biochemical parameter separately. First, the amount of moderate and severe deficiencies were calculated. Second, we investigated whether each variable (vitamins A, B1, B6, B12, D, folate, ferritin, zinc and magnesium) could predict the presence of deficiency. RESULTS: In total, 561 (LRYGB) and 831 (LSG) patients had at least preoperative and postoperative values of vitamin A, B1, B6, B12, D, folate, ferritin, zinc or magnesium. The algorithm reduces vitamin D, B12, B6, B1 and ferritin examinations by 15, 11, 28, 28 and 38%, respectively, without missing clinically relevant deficiencies. The corresponding potential cost savings was 14%. CONCLUSIONS: This study identified substantial cost savings in laboratory test for both LRYGB and LSG procedures. The potential cost reduction of 14% might even be increased to 42% when less frequent moderate deficiencies are not screened anymore, whereas >99.0 of moderate deficiencies will be detected.

Subjective outcome after laparoscopic hiatal hernia repair for intrathoracic stomach.

PURPOSE: For decades, an intrathoracic stomach (ITS) has been a definite indication for surgery due to the perceived risk of an acute volvulus with perforation, gangrene, or hemorrhage. At the present time, elective laparoscopic repair is the first choice for treatment of ITS. There is a lack of evidence in the long-term quality of life after a hiatal hernia repair for an intrathoracic stomach. METHODS: A retrospective analysis was performed on all patients undergoing a hiatal hernia repair for an intrathoracic stomach between January 2004 and January 2015. Additionally, to a hiatal closure, the patients received an antireflux procedure. Outcome measures included patient characteristics, operative details, complications, and postoperative morbidity and mortality. All patients were sent a quality of life questionnaire to assess long-term quality of life and patient satisfaction. A higher quality of life score represents a better quality of life. RESULTS: Eighty-six patients underwent laparoscopic repair for ITS, from which, one patient died during surgery. Eighty-five patients were contacted and 81 completed the questionnaire, resulting in a response rate of 95.3 %. At a median follow-up of 2.7 years (range 0.1-9.6), the mean quality of life score was 13.5 (standard deviation 2.8). The mean overall satisfaction was 8.4. There were four recurrences: three in the first 12 days after surgery and one in 2.4 years. CONCLUSIONS: Very good results in patient satisfaction and symptom reduction were achieved after a median follow-up of 2.7 years in this laparoscopic repair of the intrathoracic stomach single center experience study. The symptomatic recurrence rate was very low.

Different Supplementation Regimes to Treat Perioperative Vitamin B12 Deficiencies in Bariatric Surgery: a Systematic Review.

Vitamin B12 dosage in multivitamin supplementation in the current literature is quite variable. There is no consensus about the optimal treatment of vitamin B12 deficiency. A systematic literature search on different supplementation regimes to treat perioperative vitamin B12 deficiencies in bariatric surgery was performed. The methodological quality of ten included studies was rated using the Newcastle Ottawa scale and ranged from moderate to good. The agreement between the reviewers was assessed with a Cohen's kappa (0.69). The current literature suggests that 350 µg oral vitamin B12 is the appropriate dose to correct low vitamin B12 levels in many patients. Further research must focus on a better diagnosis of a vitamin B12 deficiency, the optimal dose vitamin B12 supplementation, and clinical relevance next to biochemical data.

Conversion to Gastric Bypass After Either Failed Gastric Band or Failed Sleeve Gastrectomy.

BACKGROUND: Roux-en-Y gastric bypass (RYGB) is still considered the gold standard in bariatric surgery. Before, adjustable gastric banding (AGB) was regarded as an alternative; nowadays, sleeve gastrectomy (SG) is a more favorable alternative. In case of unsatisfactory results, RYGB is often performed as a secondary procedure. Conversion of an AGB is associated with a high risk of complications; the hypothesis was that this would be less after conversion of an SG. METHODS: All patients undergoing conversion to RYGB after AGB or SG between 2005 and 2012 were included for retrospective analysis. Patient characteristics, operative details, postoperative complications, the relief of complaints, weight loss, reasons for failure, and evolution of known comorbidities up to 2 years were analyzed. RESULTS: A total of 178 patients were included (79.8 % female): AGB 110 (61.8 %) versus SG 68 (38.2 %). Main reasons for conversion were weight regain/insufficient weight loss (48.4 %) or dysphagia/reflux complaints (39.9 %). Surgical complications were found in 19 patients (AGB 13 vs SG 6; p = 0.530). Infectious complications occurred in 13 patients (AGB 11 vs SG 2; p = 0.135). Total body weight loss was equal between groups after 2 years (AGB 31.6 ± 11.0 % vs SG 31.6 ± 12.0 %; p = 0.998). Similar results were found in a subgroup analysis on patients undergoing conversion for additional weight loss (AGB 31.7 ± 11.7 % vs SG 27.0 ± 13.1 %; p = 0.173). CONCLUSIONS: Conversion to RYGB after failed AGB or SG showed comparable short-term results in terms of postoperative complications and weight loss.

Comparison Between Different Intramuscular Vitamin B12 Supplementation Regimes: a Retrospective Matched Cohort Study.

BACKGROUND: The incidence of vitamin B12 deficiency after bariatric surgery can range from 26 to 70 %. There is no consensus on optimal vitamin B12 supplementation in postbariatric patients. The objective of this study was to compare three different regimes. METHODS: In this retrospective matched cohort study, we included 63 patients with methylmalonic acid (MMA) levels ≥300 nmol/L. Group A (n = 21) received 6 intramuscular (im) vitamin B12 injections including a loading dose, group B (n = 21) received 3 im vitamin B12 injections without loading dose and group C (n = 21) received no im vitamin B12 injections. RESULTS: The total post-bariatric patient population consisted of 14 males (22.2 %) and 49 women (77.8 %) with a mean current body mass index of 30.6 ± 8.0 kg/m2. There was no significant difference in vitamin B12 and MMA levels between 3 groups at baseline. There was a significant difference in follow-up vitamin B12 levels of group A compared to group B (p = 0.02) and group A compared to group C (p = 0.03). In the follow-up results, there is also a significant decrease in MMA levels of group A compared to group B (p = 0.02), group A compared to group C (p < 0.001), and group B compared to group C (p < 0.01). CONCLUSIONS: In this study, a shorter injection regime is probably not sufficient to treat a vitamin B12 deficiency. An injection regime with 6 injections recovered all vitamin B12 deficiencies biochemically. MMA levels cannot recover spontaneously over time without additional im injection regime.

Improving Bariatric Patient Aftercare Outcome by Improved Detection of a Functional Vitamin B12 Deficiency.

BACKGROUND: Vitamin B12 deficiency is common after bariatric surgery. Vitamin B12 is a poor predictor of functional vitamin B12 status, since deficiencies might even occur within the reference limits. Therefore, vitamin B12 deficiencies with serum vitamin B12 levels are between 140 and 200 pmol/L remain undetected. Methylmalonic acid (MMA), however, will detect these deficiencies as accumulates due to functional intracellular vitamin B12 deficiencies. MMA is a relative expensive analysis and is therefore not generally available. To lower the costs, we only request MMA when vitamin B12 levels are between these levels. As a result, more biochemical deficiencies are found. However, it was not known whether bariatric patients with vitamin B12 levels between 140 and 200 pmol/L would benefit from supplementation. METHOD: Bariatric patients with vitamin B12 levels between 140 and 200 pmol/L with (n = 45) and without (n = 45) intramuscular hydroxocobalamin injections were compared. RESULTS: Treated patients showed a significant increase of vitamin B12 levels (P < 0.001) and a significant decrease in MMA levels (P < 0.001). Biochemical improvement occurs in both patients with and without clinical symptoms. The control group showed a significant increase of MMA levels (P < 0.001). To examine whether biochemical benefits of vitamin B12 supplementation are correlated with clinical improvement, patient records were checked for complaints. Complaints were disappeared after treatment, while no improvement was seen in untreated patients. CONCLUSION: This study shows that all bariatric patients with vitamin B12 levels between 140 and 200 pmol/L benefit clinical and biochemical from vitamin B12 supplementation, regardless the MMA levels.