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Post-op malnutrition

Vitamin and mineral deficiencies after LSG: A huge challenge

There are several known nutritional deficiencies following bariatric surgery, but the type of deficiency depends on the type of surgery
By identifying patient's nutritional deficiencies earlier, they are given an opportunity to reduce their deficiencies prior to surgery when their GI tract can absorb multivitamin supplements

Despite the many benefits of bariatric surgery, one of the long-term complications remains underreported and in some cases more worryingly, untreated. Vitamin and mineral deficiencies are one of most common complication after bariatric surgery. These shortages in essential micronutrients can lead to anaemia, hair loss and osteoporosis, as well as profound consequences reducing a patient’s quality of life, and in more severe cases, life expectancy. Although guidelines exist on nutritional deficiencies1, there is still a lack of awareness and education in both patients and doctors. In fact, research has shown that 57% of patients are micronutrient deficient within the first year of surgery.2

Bariatric News spoke with Dr. Edo Aarts, Surgical Resident and Head Bariatric Research, Rijnstate Hospital and Vitalys Clinic in Arnhem, the Netherlands, about vitamin and mineral deficiencies after bariatric surgery and specifically laparoscopic sleeve gastrectomy, and why all healthcare professional involved in bariatric surgery need to be educated about the importance of pre- and post-surgical evaluation of nutritional deficiencies.

Most post-surgical after care is done by surgeons, but post-nutritional care has only come to the forefront in the last ten years. Previously, patients were unlikely to receive post-operative care nutritional deficiency advice, despite the fact that nutritional problems are common and can continue for the duration of a patients’ lifetime after surgery. According to Dr. Aarts, this is why it is very important patients receive lifelong nutritional deficiency assessments.

There are several known nutritional deficiencies following bariatric surgery, but the type of deficiency depends on whether a patient has undergone restrictive surgery, such as the gastric sleeve, or restrictive and malabsorptive procedures such as the biliopancreatic diversion and gastric bypass procedures.

Sleeve gastrectomy

It has long been thought that deficiencies mostly occurred in procedures with a malabsorptive component, like the rouxen-y gastric bypass or the biliopancreatic diversion, only. The risk for developing deficiencies after non-bypass bariatric surgery like the sleeve gastrectomy was considered low and patients were often not even tested for deficiencies.3 However, research shows that in the restrictive types of surgery deficiencies occur almost as much.3,4

Dr. Edo Aarts

“We know that the malabsorptive component of the gastric bypass leads to deficiencies in micronutrients such as iron and vitamin B12. In addition, after a gastric bypass the ‘carrier’ intrinsic factor – which is need for the absorption of vitamin B12 – is no longer released, so there is only passive absorption,” said Dr. Aarts. “After a sleeve gastrectomy, there is usually less intake so a patient cannot eat sufficient amounts of food to obtain the adequate levels of nutrients and minerals, and patients do not have sufficient amounts of gastric acid in the stomach to convert the iron in the food into their digestive system. So even though a patient consumes ample amounts of iron it will not be absorbed and transferred from iron 3+ into iron 2+ sufficiently.”

Research by Capoccia et al. showed that following laparoscopic sleeve gastrectomy a significant proportion of patients developed vitamin B12 and folate deficiency.4 Even though Capoccia did not report any iron deficiency in this patient group, Dr. Aarts and colleagues did report an iron deficiency in 43% of the patients who had received the same procedure. In addition, anaemia was seen in 26% of patients and significantly low B12, folate, iron and vitamin D levels in this group of sleeve gastrectomy patients.3

“There is no doubt that in practice the levels of nutritional deficiencies after sleeve gastrectomy are higher than those reported in the literature. There is an urgent need to increase awareness of this problem by reporting the actual levels of nutritional deficiencies in the published literature,” said Dr. Aarts. “In our series, 28% of patients were anaemic, but the literature states only a few percent of anaemia cases per year. This is incorrect, nutritional deficiency rates after sleeve gastrectomy are grossly underreported. The sleeve gastrectomy is the number one operation in the world at the moment and the most common complications at the moment are due to deficiencies as a result of the procedure. Some patients who have undergone a sleeve gastrectomy are told they do not need supplementation, this is 100% untrue.”

 “There are a lot of things we do not know about nutritional deficiencies after bariatric surgery, and especially the sleeve gastrectomy, so more research needs to be carried out before we can say that the guidelines are sufficient.”

Overall, he said there are two primary causes of nutritional deficiency following bariatric surgery: 1) a lack of food intake and 2) changes to the gastrointestinal tract due to the surgery. The latter results in the difficulty of the absorption of food nutrients into the bloodstream of the patient’s body.

However, following weight loss surgery many patients suffer from nutritional deficiencies, while others do not have this problem. According to Dr. Aarts, there are a number of factors explaining this phenomenon, but in general it is not due to different alterations of the gastro intestinal (GI) tract that restricts the patient’s ability to absorb vitamins and minerals, but rather the patient’s lifestyles and their eating habits after surgery.

For example, those patients who have a diverse diet (fruit, vegetables, cereal, bread etc.) following surgery do have better nutritional intake compared to those patients who have a limited and unbalanced diet. Following surgery, some morbidly obese patients will lose weight, because they are restricted in the amount of food they can eat, however they are not consuming the most healthy types and/or the best variety of foods. As a result, they are not providing their bodies with the (adequate amounts of) essential nutrients required to stay healthy – resulting in the deficiencies seen in many of our patients.

“If you combine a poor diet with a reduction in the malabsorptive capabilities of the GI tract, following surgery, this compounds a patient’s nutritional deficiencies. This combination is why many patients present with nutritional deficiencies within the first year of surgery,” he explained.

He added that there is also a difference between male and female patients – premenopausal female patients do not have the same iron reserves of their male counterparts because many of the female patients are still fertile and lose iron due to their menstrual cycle.

“This is the same as in the general population, but of course this lack of iron is exacerbated after bariatric surgery,” he added.

In his experience, the most common deficiencies are iron, vitamin B12, folic acid and vitamin D. Vitamin D is particularly important for bone density, but this deficiency goes unnoticed by patients as it takes years before it becomes a real problem. For example, osteoporosis is now a significant problem among those bariatric patients who have undergone surgery 15-20 years ago, Dr. Aarts explained.

Pre-operative assessment

By performing pre-operative nutritional assessments at his centre, Dr. Aarts and colleagues have reported that one in four obese patients have nutritional deficiencies and are malnourished due to a lack of diversity in their diet. Furthermore, because these patients rarely leave their house, many present with vitamin D deficiency.

“We must keep in mind that it is much easier to provide multivitamin supplements before surgery, because the GI tract has not been altered, for this reason it is imperative that patients have pre-operative testing to identify which nutritional deficiencies they have, so they can be treated pre-operatively.”

He added that it is much more difficult to supplement patients after surgery. Therefore, by identifying their nutritional deficiencies earlier, patients are given an opportunity to reduce their deficiencies prior to surgery when their GI tract can absorb multivitamin supplements well yet.

“We know that testing for nutritional deficiencies prior to surgery and prescribing supplements before surgery give patients the opportunity to build up the vitamin and mineral levels in the body, which results in a reduction in post-operative complaints such as fatigue. The evidence shows that patients are far less likely to suffer from short- and long-term nutritional deficiencies when provided with adequate pre-operative nutritional supplements.”

For over ten years, Dr. Aarts has been researching vitamin and nutritional deficiencies in bariatric surgical patients. He soon noticed that a large amount of time and expense was spent on nutritional supplements for patients after bariatric surgery. As a result, he has started to develop different multivitamins for gastric bypass patients. In 2008, he started working with the Dutch company, FitForMe (Rotterdam, The Netherlands).

The result of this collaboration was the product WLS Forte, launched in 2009, a specially designed multivitamin supplement formulation for gastric bypass patients. In 2011, Dr. Aarts and colleagues at Rijnstate Hospital started the Vitaal Study, a randomised clinical trial in which the researchers evaluated the effectiveness of WLS Forte compared with standard multivitamin supplement (sMVS). The latter contained approximately 100% of the recommended daily allowance (RDI) for iron, vitamin B12, and folic acid. WLS Forte contains vitamin B12 14000% (RI – reference intake), iron 500% RI, and folic acid 300% RI.

In total, 148 patients (74 in each group) underwent a gastric bypass and the effect of the daily consumption of one-a-day multivitamins was recorded. The results showed that sMVS treatment was associated with a decline in ferritin (-24.4 ± 70.1 μg/L) and vitamin B12 (-45.9 ± 150.3 pmol/L) over 12 months, whereas in WLS Forte patients, ferritin remained stable (+3.2 ± 93.2 μg/L) and vitamin B12 increased significantly (+55.1 ± 144.2 pmol/L). The number of patients developing ferritin or vitamin B12 deficiency was significantly lower with WLS Forte compared with sMVS (p< 0.05). Iron deficiency was reduced by 88% after WLS Forte compared with sMVS.5

A year later, 148 sleeve patients were randomised to receive either WLS Optimum (n=74) or a standard multivitamin (n=74). The WLS Optimum is a specially designed multivitamin supplement formulation for sleeve gastrectomy patients, with different dosages WLS Forte. The one-year results revealed that the patients who had WLS Optimum presented with almost no iron and B12 deficiencies, compared to approximately 12% of patients with iron and B12 deficiencies in the earlier versions of WLS Optimum multivitamin supplements. Taking into account the lack of both vitamin B12 and iron, the especially designed multivitamin supplement for gastric bypass (WLS Forte) increases the RI amounts by 14,000% and 500%, respectively (Table 1).

For gastric sleeve patients (WLS Optimum), the recommended daily amounts of both vitamin B12 and iron were increased by 400% and 1,500%, respectively (Table 2).

Compliance, education and standards of care

“We know that compliance in this group of patients is poor, so if they have to take two capsules a day it is very rare that they will take both. For this reason, we specifically designed both WLS Forte and Optimum products to be a single, one-a-day capsule, as this would optimise compliance. As a result, we have seen compliance rates almost double, just by reducing their intake to a single capsule a day.”

Although the vast majority of multivitamin supplements are taken orally, patients who present with severe nutritional deficiencies are prescribed intravenous (IV) vitamin therapy. Dr. Aarts stressed that this is more invasive, more expensive and time consuming for the patients and the Dutch healthcare system, more time consuming and certainly less comfortable for the patient compared with taking a one-a-day easy-to-swallow capsule.

“This is why it is imperative that patients are educated about the dangers of nutritional deficiencies and the importance of maintain complying with their regimen. Patients who do not attend follow-up sessions are the ones who are not compliant – we need to find ways to identify these patients.” he said. “The one-a-day capsule has also resulted in a remarkable increase in the number of patients complying with their regimen, which has allowed us to reduce their follow-up appointments from once every six months to once every year. This is more convenient for the patients and saves the patients and healthcare provider considerable time and expense. Each time we identify a patient with nutritional deficiencies they have to attend the clinic an additional three times.”

In the Netherlands, it is estimated that these additional visits cost each deficient patient an extra €370 a year.

“I believe that we should look for nutritional deficiencies only in some key vitamins and minerals because if you do not have any nutritional deficiencies in these main areas it is very unlikely you will have nutritional deficiencies in the smaller micronutrients. By concentrating on the key nutrients it would save a lot of time, effort and expense for the patients and healthcare provider. We need to develop standards of care for our bariatric patients so that it is easier for patients and healthcare professionals to ascertain exactly what nutritional supplements are being provided. More needs to be done to educate physicians, surgeons, nutritionists, nurses, dieticians, endocrinologists etc. about nutritional deficiencies before and after bariatric surgery, about the different types of supplements and how to care for a patient who underwent bariatric surgery ten years previously, who is admitted to the intensive care unit and presenting with severe nutritional deficiencies,” he concluded. “There are a lot of things we do not know about nutritional deficiencies after bariatric surgery, and especially the sleeve gastrectomy, so more research needs to be carried out before we can say that the guidelines are sufficient.”

Dr. Aarts will be presenting the fouryear results from WLS Optimum study – (H10.2/O.168: Vitamin and mineral deficiencies after Sleeve Gastrectomy: four-year results of an RCT) at 16:45 in the Albert Suite, on Friday 1st September, at the XXII IFSO World Congress in London, UK.

At XXII IFSO World Congress, in London, UK, FitForMe will be launching the optimized WLS Optimum and WLS Forte. In addition to these products, Dr. Aarts and his colleagues, and FitForMe have also developed the WLS Maximum, a multivitamin for use after biliopancreatic diversion or duodenal switch. The company will soon be introducing WLS Primo, a specially designed multivitamin supplement formulation for mini-gastric bypass or one single anastomosis gastric bypass patients. To find out more information, please visit the FitForMe stand, no. 9, the Flemming Area, in the Exhibition Hall.


For more information, please visit:

  1. Mechanick JI, Youdim, A, Jones DB, Garvey WT, Hurley DL, McMahon MM, Heinberg LJ, Kushner R, Adams TD, Shikora S, Dixon JB, Brethauer S. AACE/TOS/ASMBS Guidelines. Clinical Practice Guidelines for the perioperative Nutritional, Metabolic and Nonsurgical Support of the Bariatric Surgery Patient – 2013 Update: Cosponsored by American Association of Clinical Endocrinologists, The Obesity Society, and American Society for Metabolic & Bariatric Surgery. 2013. Surg Obes Relat Dis 9, 159-191
  2. Gehrer S, Kern B, Peters T, Christofiel-Courtin C, Peterli R. 2010. Fewer nutrient deficiencies after laparoscopic sleeve gastrectomy (LSG) than after Laparoscopic Roux-Y-Gastric Bypass (LRYGB) – a prospective study. Obes.Surg vol.20, no.4: pp447-453
  3. Aarts EO, Janssen IMC, Berends FJ. 2011. The gastric sleeve: losing weight as fast as micronutrients? Obes Surg. 21:207-11
  4. Capoccia D, Coccia F, Paradiso F, Abbatini F, Casella G, Basso N, Leonetti F. 2012. Laparoscopic gastric sleeve and micronutrients supplementation: our experience. J Obes 2012:1-5
  5. Optimization of vitamin suppletion after Roux-en-Y gastric bypass surgery can lower postoperative deficiencies: a randomized controlled trial. Dogan K1, Aarts EO, Koehestanie P, Betzel B, Ploeger N, de Boer H, Aufenacker TJ, van Laarhoven KJ, Janssen IM, Berends FJ. Medicine (Baltimore). 2014 Nov;93(25)

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