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Micronutrient Deficiencies After Bariatric Surgery

As I’ve often blogged before, currently bariatric surgery is the most effective long-term treatment for the majority of patients with severe obesity. Nevertheless, as I have also blogged about on several occasions, obesity surgery is far more than just about surgery and all surgical patients will require lifelong monitoring of their nutritional status. 

A paper by Padmini Shankar and colleagues from the Georgia Southern University, just published in Nutrition, nicely outlines the many micronutrient deficiencies that can occur in patients who have undergone bariatric surgery.

Their systematic review shows that bariatric surgery patients are particularly at risk for deficiency of: vitamins B(12), B(1), C, folate, A, D, and K, along with the trace minerals iron, selenium, zinc, and copper.

As they point out, some of these nutritional deficiencies can be particularly critical for women who become pregnant after surgery (by no means a rare event): iron, vitamin A, vitamin B(12), vitamin K, and folate deficiencies are all associated with maternal and fetal complications, including severe anemia, congenital abnormalities, and low birth weight and failure to thrive.

Importantly, simply taking the usual dose of an over-the-counter multivitamin and mineral supplement does not provide adequate amounts of certain nutrients such as vitamin B(12), iron, or fat-soluble vitamins and most patients will require additional doses of prophylactic supplementation life-long to maintain optimal micronutrient status.

Clearly, all bariatric surgery patients would benefit from regular monitoring of serum nutrient levels starting at 3 mo after surgery and periodically thereafter.

As many bariatric patients start out with significant micronutrient deficiencies, correcting these prior to surgery may also not be a bad idea. 

Edmonton, Alberta


  1. Do micronutirent deficiencies occur with all forms of bariatric surgery? Does, for example, gastric banding, which leaves the digestive tract in place, result in the same micornutirent deficiencies as more radical surgeries?

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  2. I had RNY in Sept. 08.
    Since then, according to my surgeon’s directions, I have been taking: 1 B-12 / 2 multivit. / D3 / Calcium with D and Iron … I also have regular blood tests to make sure there are no deficiencies.
    Before surgery, I NEVER took any of these because my alimentation (grains, vegetables, fruits) provided all the minerals and vitamins needed…RNY saved my life… I will continue to follow my surgeon’s directions.

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  3. HI, I am over 6 years post op (rouxeny) and I am trying to get the balance of the micronutrients right. However, this is challenging, as in NZ my specialist (endocrinologist) does not seem to take changes in labs seriously. I used to have good access to medical journals – as I was studying. But I do not have that access now.
    What do you recommend, I have been low in iron and vitamin D and zinc. These are now in the low “normal” range. I appear to have hyperparathyroidism and I have increased my Vtamin D and now the endocrinologist doesn’t want to see me till next year. Are my bones thinning as we speak?


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