Neurologic Disorders Caused by Micronutrient Deficiencies

Metabolic and bariatric surgery (MBS) procedures have undoubtedly improved the health and quality of life of millions of people globally. In 2014, it was estimated that 150,000 of these procedures were performed in the US alone.1 While these types of surgeries are considered safe, they do pose some risks related to postoperative micronutrient deficiencies, especially if preoperative nutrition status is deficient.

Neurological disorders as a result of nutrient deficiencies are one such risk. These conditions affect the nerves, potentially impacting organ function. They can include a variety of symptoms and are caused by a deficiency in various vitamins and minerals including:2-4

  • Thiamin
  • Vitamins B12, B6, and E
  • Folate
  • Copper

Studies confirm that for bariatric surgery patients, neurological disorders are primarily the result of vitamin/mineral deficiencies,2 and immediate diagnosis and prompt treatment are critical for preventing long-term, irreversible damage.1 Neurologic complications can occur as a result of vitamin and mineral deficiencies several weeks, months, or years after any MBS procedure and can negatively impact quality of life.

What exactly are these disorders?

In recent years, a new condition—“bariatric beriberi”—has been termed. It is the result of low thiamin levels and can lead to devastating consequences such as muscle paralysis and heart failure. If thiamin levels are not improved, it can become life-changing. Other neurological conditions that can result from nutrient deficiency include Wernicke’s encephalopathy and Korsakoff syndrome. Wernicke’s encephalopathy is a neuropsychiatric condition caused by the depletion of thiamin in brain cells, and Korsakoff syndrome is a chronic memory disorder caused by thiamin deficiency.7

Myth: Neurologic disorders resulting from nutrient deficiencies are unique to malabsorptive procedures

Gastric bypass, which is both restrictive and malabsorptive, is the procedure most associated with micronutrient deficiencies (specifically, folate, B12, and thiamin)3 linked to neurological complications.  However, it is unsafe to assume that restrictive-only procedures do not put one at risk for nutritional deficiency that can ultimately result in devastating neurological complications. In fact, the most recent reports suggest that one out of every three bariatric patients has a thiamin deficiency prior to surgery.1 The best way to avoid a thiamin deficiency is through consistent dietary intake and supplementation along with frequent monitoring of nutrient status, by a health care provider, via lab draws.

When do these conditions occur after MBS?

Researchers and clinicians have recognized that each condition tends to be associated with unique nutrients at certain stages postoperatively:

  1. Wernicke encephalopathy (due to thiamin deficiency) is among the more c­ommon early complications.
  2. Myelopathy and myeloneuropathy (resulting from vitamin B12 or copper deficiency)2 are considered late complications.
  3. Polyneuropathy is associated with inadequate B12, B6, and vitamin E and tends to be a late complication.

Similarly, it is generally accepted that:

  1. Thiamin deficiency can develop in the first weeks or months following surgery.
  2. B12 deficiency may occur anywhere from a few years to many years following surgery.
  3. Copper deficiency generally is a late-developing complication (several to many years after surgery).5

As with health in general, prevention is key. And in the case of neurological disorders resulting from nutrient deficiencies, prevention means ensuring adequate micronutrient status for optimal nerve health. Knowing your preoperative micronutrient status and following a postoperative lab schedule to evaluate for adequacy are important steps in taking necessary precautions toward prevention of one of these potentially irreversible conditions.

Consistency is another critical component. Although most patients have good intentions, many discontinue their surgeon-recommended vitamin and mineral supplement recommendations after many years’ worth of normal lab results, believing that risks are now behind them. However, reducing recommended intakes and/or discontinuing supplementation can lead to these unfortunate conditions. Maintaining a regular supplement regimen is therefore an important step in reducing the risk for neurological complications that can occur long after the procedure.

By following the American Society for Metabolic and Bariatric Society’s guidelines6 below for oral supplementation and following up with their health care provider lifelong, MBS patients help prevent harmful neurologic conditions related to nutrient deficiencies. Current guidelines for preventing nutrient deficiencies that affect nerve health suggest the following:

Thiamin 12 mg daily (minimum), 50 mg from B-complex supplement or multivitamin once or twice daily (preferred)
Vitamin B12  350–500 mcg daily
Vitamin B6 100-200% DV daily
 Vitamin E 15 mg daily
Folate 400-800 mcg daily
800-1000 mcg daily (women of childbearing age)
Copper* 200% of RDA (2 mg/d) BPD/DS or RYGB
100% of RDA (1 mg/d) SG or LAGB

*In the post-MBS patient, supplementation with 1 mg copper is recommended for every 8-15 mg of elemental zinc to prevent copper deficiency.

BPD/DS: Biliopancreatic Diversion with Duodenal Switch, RYGB: Roux-en-Y Gastric Bypass, SG: Sleeve Gastrectomy, LAGB: Laparascopic Adjustable Gastric Band



  1. Berger JR & Singhal D. The neurologic complications of bariatric surgery. Handb Clin Neurol. 2014;120:587-94.
  2. Kumar N. Neurologic complications of bariatric surgery. Continuum (Minneap Minn).2014 Jun;20(3 Neurology of Systemic Disease):580-97.
  3. Saab R, El Khoury M, & Farhat S. Wernicke’s encephalopathy three weeks after sleeve gastrectomy. Surg Obes Relat Dis.2014 Sep-Oct;10(5):992-4.
  4. Dudorova EY, Damulin IV, Khatkov IE. [Neurological complications due to vitamin deficiencies after bariatric surgery]. Ter Arkh.2015;87(12):117-121.
  5. Rudnicki SA. Prevention and treatment of peripheral neuropathy after bariatric surgery. Curr Treat Options Neurol. 2010 Jan;12(1):29-36.
  6. Parrott, Julie et al. American Society for Metabolic and Bariatric Surgery Integrated Health Nutritional Guidelines for the Surgical Weight Loss Patient 2016 Update: Micronutrients. Surg Obes Relat Dis. 2017 May;13(5):727-741.
  7. Alzheimer’s Association. Korsakoff Syndrome. Alzheimer’s Association,