Friday, March 12, 2010

Guest post by Matthew Constantin, PhD (biochemist)

The Importance of Multivitamin Supplementation Following Bariatric Surgery

In a peer-reviewed article entitled “Nutritional Deficiencies following Bariatric Surgery: What have we learned?”, Richard Bloomberg, MD of the Mount Sinai School of Medicine, and his team study the importance of nutritional supplements following bariatric surgery. Research shows that following bariatric surgical procedures, vitamin and nutrient deficiencies are common. A close examination of these deficiencies after weight loss surgery shows that supplements should be a standard post-operative element so that potential nutritional complications will be minimized [1].

Roux-en-Y gastric bypass (RYGBP), biliopancreatic diversion with duodenal switch (BPD-DS), and biliopancreatic diversion without duodenal switch (BPD) are three commonly performed bariatric surgeries. These surgical interventions work by reducing the size of the stomach (restriction) and preventing the absorption of food in the gastrointestinal tract (malabsorption).

While bariatric surgery results in significant weight loss, the malabsroptive nature of the operation can severely compromise the ability of the body to absorb vital nutrients, such as protein and iron, causing nutritional deficiencies. Restrictive techniques, such as gastric banding or sleeve gastrectomy, are less likely to cause nutritional deficiencies comparing to malabsorptive techniques. This is because restrictive procedures do not directly affect food absorption in the small intestine. If a deficiency occurs after a restrictive procedure, this is usually the result of food intolerance or the tendency of the patient to avoid certain nutrient-rich foods postoperatively. This article focuses on the effect of malabsorptive procedures (RYGBP, BPD-DS and BPD) on the absortion of protein, iron, vitamin B12, folate, calcium, vitamin D, thiamine and fat-soluble vitamins.

Nutrients Deficiencies


Protein deficiency after bariatric surgery has been well documented. This is most likely the result of bypassing of the small intestine where protein is absorbed in the body. Protein deficiency occurs usually in BPD and BPD-DS surgeries. A study done by Marceau et al [2] found that there was a high incidence of protein deficiency after BPD and BPD-DS surgeries with 11% of patients having serum albumin levels lower than 3.5 g/dL. The normal serum albumin levels for adults are 3.5-5.0g/dL. In another study, 3.7% of patients who underwent BPD needed to be re-hospitalized because of the severe protein deficiency they presented. Dietetic counseling and increased protein intake aided in preventing further recurrences of the deficiency.


Iron deficiency can occur in both restrictive and malabsorptive operations. In the case of malabsorptive procedures, iron deficiency results from the fact that the duodenum and proximal jejunum (the part of the small intestine right after the stomach) is bypassed. Iron deficiency has been shown to increase in RYGBP patients during the first 5 years postoperatively [3]. Other studies however, such as the one by Rabkin, who studied BPD-DS patients, have found that iron levels were normal over a period of 3 years [4].

Vitamin B12 and Folate Deficiency

Bariatric surgery usually affects the absorption of vitamin B12 and folate. B12 is absorbed in the terminal ileum, the portion of the small intestine the stomach is connected to in the BPD procedure. Almost one third of all patients studied by Halverson and colleagues were deficient in B12 and two thirds were deficient in folate, one year after gastric bypass [5]. It is noteworthy that patients can present deficiency in these two nutrients even if their vitamin levels are normal preoperatively. Studies have shown that regular supplementation with B12 and folate after the surgery can prevent deficiency of these two vitamins.

Vitamin D And Calcium Deficiency

Vitamin D is absorbed in the jejunum and ileum, while calcium is absorbed in the duodenum and proximal jejunum. Since bariatric operations result in bypassing of these segments of the small intestine, vitamin D and calcium deficiencies are a common phenomenon in weight loss surgery patients. Calcium deficiency can lead to potential bone loss and increase the long-term risk of osteoporosis. In fact, some retrospective studies have shown evidence of postoperative metabolic bone disease. Calcium and vitamin D deficiency rates can be as high as 50% [6], and while many morbidly obese patients already suffer a lack of these nutrients pre-operatively, the deficiency is exacerbated after the surgery. Often, supplementation may not be enough to correct low calcium and abnormal vitamin D levels. A study of BPD patients by Slater et al showed significant deficiencies in calcium and vitamin D, despite supplementation [7].

Thiamine (Vitamin B1) Deficiency

The deficiency of this vitamin is relatively rare. Studies have shown that thiamine deficiency occurs in only 1 every 5800 bariatric patients [8]. Treatment with thiamine (intravenously or intravascularly) resolves the deficiency as quickly as one day and no more than four months after the surgery.

Other Fat-Soluble Vitamin Deficiencies

Vitamin A

Levels of Vitamin A were found to be low in 61% of patients undergoing BPD with or without duodenal switch, despite the fact that 4 out of 5 patients were compliant with vitamin supplementation.

Vitamin E

Vitamin E deficiency is uncommon and occurs after malabsorptive operations, usually BPD. Patients who receive multivitamin supplementation can effectively sustain normal levels of vitamin E after the surgery. A study by Slater showed that 96% of BPD patients who were taking vitamin supplements had normal levels of vitamin E even 4 years postoperatively.

Vitamin K – Magnesium – Zinc

There has been no substantial evidence to suggest deficiency of vitamin K after surgery.

Magnesium levels do not seem to be significantly affected by bariatric surgery. One study found that magnesium concentration remained normal 4 and 10 years after BPD surgery, while another one found that only 5% of patients had low magnesium levels 2 years after surgery.

Zinc deficiencies have been found in as many as 50% of BPD-DS patients and in only 10.8% of BPD patients. Interestingly, 80% of these patients where taking multivitamins.


Clearly, there is a great deal of clinical research that indicates that vitamin and nutrient deficiencies do occur after bariatric procedures. It is because of this that the use of supplements may be more commonly recommended after the surgeries. Additionally, it seems that more research should be done to investigate the impact of such supplements on the deficiencies and the resolution rates.


1. Bloomberg, RD, Fleishman, A, Nalle, JE, Herron, DM, Kini, S. Nutritional Deficiencies following Bariatric Surgery: What Have We Learned? 2005. Mount Sinai School of Medicine. Obesity Surgery 15: 145-154.

2. Marceau S, Biron S, Lagace M et al. Biliopancreatic diversion, with distal gastrectomy, 250 cm and 50 cm limbs: long-term results. Obes Surg 1995; 5: 302-7.

3. Skroubis G, Sakellaropoulos G, Pouggouras K et al. Comparison of nutritional deficiencies after Roux-en-Y gastric bypass and after biliopancreatic diversion with Roux-en-Y gastric bypass. Obes Surg 2002; 12: 551-8.

4. Rabkin RA, Rabkin JM, Metcalf B et al. Nutritional markers following duodenal switch for morbid obesity. Obes Surg 2004; 14: 84-90.

5. Halverson JD. Micronutrient deficiencies after gastric bypass for morbid obesity. Am Surg 1986; 52: 594-8.

6. Brolin RE, LaMarca LB, Kenler HA et al. Malabsorptive gastric bypass in patients with superobesity. J Gastrointest Surg 2002; 6: 195-203; discussion 4-5.

7. Slater GH, Ren CJ, Siegel N et al. Serum fat-soluble vitamin deficiency and abnormal calcium metabolism after malabsorptive bariatric surgery. J Gastrointest Surg 2004; 8: 48-55; discussion 4-5.

8. Chang CG, Adams-Huet B, Provost DA. Acute postgastric reduction surgery (APGARS) neuropathy. Obes Surg 2004; 14: 182-9.

About the Author

Matt Papa, PhD, has dedicated a great deal of his research time to better understand the elements of bariatric surgery as well as the benefits and complications. He is excited he was given the opportunity to share some scientific facts with the BlubberyBlogger community. In his website he presents research findings  and posts practical information on the topic of weight loss surgery, and offers a coupon for Medifast and a coupon code for Nutrisystem.



Matthew said...

Lynn, thanks for posting my article. It's an honor for me to be connected to this wonderful community of people who are fighting the good fight.

Jen said...

Thanks for that info Lynn, it's very interesting. At my 12 month bandiversary, I had my blood tests done and I was only low in folate. Interesting because my nails are so brittle and my hair continues to fall out, so there must be something going on! I have just brought a liquid vitamin supplement today in an attempt to ensure I am getting enough nutrients.

*** Matt said...

Hi Jen,
it's really great that your blood tests are good!