Bariatric surgery has become a more frequently utilized option for many people dealing with intractable obesity. Losing weight benefits health in many ways, including improving blood sugar control and heart health.

Bariatric surgery means that you’ve made a lifelong commitment to taking recommended dietary supplements along with eating a healthy diet.

Bariatric Surgery

There are three main types of bariatric surgery: Roux-en-Y gastric bypass, adjustable gastric banding, and biliopancreatic diversion/duodenal switch. All types of bariatric surgery reduce the body’s ability to absorb nutrients.

It’s hard enough for people in the general population to fully meet their nutritional needs without supplementation, but even harder for someone who has undergone bariatric surgery.

It is important to understand that you are no longer able to get your nutritional needs met through diet alone – no matter which type of bariatric surgery you choose. This is because the surgery reduces the ability of the body to absorb nutrients.

Studies have shown that nutritional deficiencies are common in bariatric patients. The nutrient deficiencies most commonly found in bariatric patients include iron and B vitamins (B12, B1, folate and vitamin B6). Other common deficiencies include protein, essential fatty acids, calcium and vitamins A, C, D, K, and E.[i]

Nutritional deficiencies in bariatric patients include low iron[ii]  and certain neurological dysfunctions.[iii]

Which Vitamins to Choose?

Because absorption can be an issue with people who have bariatric surgery, bioavailability of the nutrients in the supplement you choose is important. Vitamins come in different forms (or types) and you need the ones most easily absorbed.

Following surgery, a chewable, liquid, or powdered form of nutrients is the best choice.

Recommended Lifetime Supplementation for Bariatric Patients:

  • A Multivitamin/Multimineral: For people with adjustable gastric banding, 100% of the Daily Value (DV) from a vitamin and mineral supplement is recommended. For people with Roux-en-Y gastric bypass and biliopancreatic diversion/duodenal switch, 200% of the Daily Value (DV) is recommended.[iv] Some supplements are designed to contain 200% in a single serving, but it is also acceptable (and even preferable) to take your supplements more than once a day to increase absorption.

In addition to a multivitamin/multimineral:

  • Calcium: Added calcium is a good idea for anyone, but especially for gastric bypass patients. Once again, it is best to take calcium in divided doses (2-3 times a day).
  • B-vitamins: The B-vitamins (especially vitamin B12) is important for people with gastric bypass. An additional B-vitamin supplement is a good idea.
  • Vitamin D: is a common shortfall nutrient and is easy to supplement.
  • Iron: Another common deficiency is iron. Women who are still menstruating are at greatest risk and need to consider adding in an iron supplement.
  • Omega 3: Fish oil is a good source of Omega 3 fatty acids that are much needed in people after bariatric surgery. Gel caps or chewable forms are acceptable.

Protein is another important need for people with gastric bypass, so a meal replacement protein shake is a great idea.

Stay Ahead of the Game

The important thing to remember about nutrition is that it is easy to fall behind and difficult to correct. When your blood tests show your Vitamin D level is low, it can take months to bring levels back up to normal. Other nutrients are the same.

It is essential to make daily supplementation a life-long habit. A liquid or powdered multivitamin is your best choice. Look for a product that not only provides you vitamins and minerals but ideally also protein and dietary fiber.

As always, discuss any supplementation with your physician.


[i] Xanthakos SA. Nutritional deficiencies in obesity and after bariatric surgery. Pediatr Clin North Am. 2009 Oct;56(5):1105-21. PMID: 19931066.

[ii] Brolin RE, LaMarca LB, Kenler HA, Cody RP. Malabsorptive gastric bypass in patients with superobesity. J Gastrointest Surg. 2002 Mar-Apr;6(2):195-203. PMID: 11992805.

[iii] Berger JR. The neurological complications of bariatric surgery. Arch Neurol. 2004 Aug;61(8):1185-9. PMID: 15313834.