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Page 2 of 7 Çalapkorur et al. Mini-invasive Surg 2020;4:15 I http://dx.doi.org/10.20517/2574-1225.2019.51

[5,6]
improvements in surgical procedures . The goal of bariatric surgery, which is an effective treatment for
[5]
morbid obesity, is to achieve weight loss in the patient and improve his/her quality of life .

Bariatric surgery methods are classified as restrictive, malabsorptive, and combined methods according to
the effect mechanism. In restrictive methods, a small gastric sac is created to limit the amount of food the
patient can consume at one time. In malabsorptive methods, a part of the small intestine is bypassed and
consequently the absorption of nutrients decreases. In combination methods, both mechanisms are used to
[7]
achieve weight loss .

Several studies have shown that bariatric surgical procedures ensure weight loss and improvement in
metabolic parameters in morbidly obese individuals [8-10] . However, these individuals need to be evaluated
[11]
for long-term complications of the surgery . One of the most common complications after bariatric
surgery is vitamin deficiencies. Vitamin deficiencies have been observed in patients who underwent
malabsorptive surgery due to absorption disorder and in patients who underwent restrictive surgery due to
[12]
inadequate intake .

In a study conducted on subjects during the first year following a Roux-en-Y gastric bypass (RYGB),
which is a malabsorptive method, vitamin A deficiency in 11% of patients, vitamin C deficiency in 34.6%
of patients, vitamin D deficiency in 7% of patients, thiamine deficiency in 18.3% of patients, riboflavin
[13]
deficiency in 13.6% of patients and vitamin B12 deficiency in 13.6% of patients were found . Similarly,
in another study, in the first year following RYGB, vitamin D deficiency in 12% of patients, vitamin B12
[14]
deficiency in 60% of patients, and folic acid deficiency in 47% of patients were determined .
Literature data show that patients who have undergone bariatric surgery are at risk for vitamin B12,
thiamine, folic acid, and vitamin A, D, and K deficiency [15-19] . These deficiencies in patients can be observed
in a wide range together with systematic and neurological findings. Therefore, regular monitoring of
[20]
vitamin levels as well as initiating supportive treatment in the case of deficiency is very important .

This review aims to provide information about vitamin deficiencies seen after bariatric surgeries and
prevention methods in the light of the literature.

WATER-SOLUBLE VITAMINS
Thiamine
It is reported that thiamine deficiency, which usually occurs within 4-6 weeks after surgery, is observed
[12]
in approximately 30% of patients . For this reason, the European Federation of Neurological Societies
recommends postoperative monitoring of the thiamine levels of patients for at least 6 months and, where
[21]
necessary, performing parenteral thiamine supplementation .
A 100-mg oral thiamine supplementation twice a day is the standard treatment for thiamine deficiency.
Patients with symptoms of Wernicke’s encephalopathy or acute psychosis need to be kept under medical
surveillance in the hospital. These patients should receive at least 250 mg/day thiamine intramuscularly or
intravenously for 3-5 days [20,22,23] . If thiamine deficiency after bariatric surgery cannot be treated with oral
thiamine supplementation, it is associated with excessive bacterial growth in the small intestine. Antibiotic
[15]
treatment is needed to overcome this deficiency, which is called bariatric beriberi .
Riboflavin
[13]
Biochemical rather than clinical riboflavin deficiency was reported after bariatric surgery . If there are findings
associated with riboflavin deficiency such as dermatitis, stomatitis, and glossitis in patient, and riboflavin
deficiency is also observed biochemically, riboflavin deficiency should be eliminated with 5-10 mg/day oral
riboflavin supplementation [20,23,24] .