Patients face vitamin deficiencies years after bariatric surgery

A new review explains why dangerous vitamin deficiencies - from vision loss to life-threatening complications - harm patients years after weight-loss surgery and how closer monitoring could save lives.

Although bariatric surgery is an effective treatment for severe obesity, it can lead to nutritional deficiencies. Researchers conducted a systematic review to understand what nutritional deficiencies occur after bariatric surgery, what factors contribute to them, and what prevention strategies are available. The review is published in the journal Clinical Obesity.

Bariatric surgery: an effective intervention for severe obesity

According to a 2022 report, one in eight people in the world live with obesity. Obesity is a complex disease characterized by excess accumulation of fat in the body, which has negative effects on health. People with severe obesity are often recommended to undergo bariatric surgery, which is commonly referred to as weight loss surgery and involves changes in the digestive system.

Bariatric surgery is a cost-effective intervention with benefits that extend beyond weight loss. For example, the procedure has been shown to be helpful in alleviating type 2 diabetes, improving hypertension, and reducing cardiovascular disease. Despite the benefits, bariatric surgery is also associated with certain complications, such as nutritional deficiencies. Previous studies have shown that micronutrient deficiencies can occur even years after surgery.

Given the complications of bariatric surgery, the European Association for the Study of Obesity (EASO) has recommended lifelong post-operative follow-up. It advises patients to take daily micronutrient supplements and to be screened regularly for nutritional deficiencies. In England, the National Institute for Health and Care Excellence (NICE) requires patients to be followed up by specialist bariatric services for at least 2 years. After this, patients are advised to undergo nutritional screening and receive appropriate supplementation as part of a shared care model.

Despite EASO and NICE recommendations, only around 5% of patients receive adequate long-term follow-up in primary care. Lack of access to specialist services, funding and inadequate training of care staff contribute to inadequate post-operative care. This leaves patients vulnerable to nutritional deficiencies, which can significantly impact their health.

Previous studies have identified multiple deficiencies in long-term follow-up after bariatric surgery, including vitamin E, D, A, K, and B12. However, the current review highlights that vitamin D deficiency was the most commonly reported (23 cases), followed by vitamin A (15 cases) and copper (14 cases), and that common deficiencies such as iron and anemia are likely underreported because case reports typically focus on rare or more severe outcomes.

It is essential to study real clinical cases of patients after surgery to identify nutritional deficiencies and the problems they face during follow-up. This strategy will help to identify factors contributing to deficiencies and reasons for treatment variability.

About the review

This systematic review included all adults who had undergone various types of bariatric surgery, such as gastric band placement, sleeve gastrectomy, gastric bypass, and duodenal switch, and who developed postoperative deficiencies in one or more micronutrients included in national monitoring recommendations. Less common procedures, such as jejunal bypass, vertical banded gastroplasty, single anastomosis gastric bypass, and combinations, such as sleeve gastrectomy with duodenal switch, were also reported in a few cases.

Only patients who had undergone bariatric surgery ≥ 2 years previously were included in the study, as this is the period during which patients are transferred from specialist services to primary care. All relevant articles published from January 2000 to January 2024 were retrieved from MEDLINE and EMBASE databases.

The Impact of Vitamin Deficiency in Patients After Bariatric Surgery

A total of 83 cases were retrieved that met the inclusion criteria described in 74 articles. Most of the selected cases were from the United States, followed by Italy, Belgium, Spain, the United Kingdom, France, Greece, Australia, Germany, Israel, Austria, Denmark, Taiwan, Brazil, Canada, and the Netherlands.

Approximately 84% of participants were women, 16% were men, and their ages ranged from 22 to 74 years. It should be noted that pregnant, postpartum, and lactating women were also included in the review. Some of these cases included serious complications in infants, including intracranial hemorrhage, microphthalmia, premature birth, and even death, highlighting the severity of untreated deficiency in this group.

The majority of participants underwent Roux-en-Y gastric bypass (RYGB), followed by biliopancreatic diversion (BPD), classic gastric bypass, laparoscopic gastric band placement, duodenal switch, and jejunal bypass. A limited number of patients also underwent sleeve gastrectomy, single-anastomosis gastric bypass, vertical banded gastroplasty, and sleeve and duodenal switch combinations. The time since surgery ranged from 2 to 40 years.

Of the 83 cases, 65 had a single identified deficiency that resulted in clinical complaints; the remainder described multiple deficiencies. Among the 65 cases, patients demonstrated deficiencies in vitamins A, D, copper, zinc, vitamin B12 and folate, thiamine and selenium.

Patients with vitamin A deficiency often developed ophthalmologic symptoms such as night blindness, decreased vision, corneal ulceration, eye pain, and photophobia. They were given oral vitamin A supplements, intramuscular (IM), or intravenous (IV) replacement via total parenteral nutrition (TPN). Some patients were given vitamin A eye ointments or other ophthalmic agents.

Patients with copper deficiency also had deficiencies in vitamin A, iron, zinc, vitamin D, and vitamin B6. These patients developed chronic liver failure along with neurologic (eg, neuropathic pain, paresthesia, weakness, sensory loss, ataxia, gait disturbance, and falls) and ophthalmologic (eg, vision loss and blurring) symptoms. Treatment with oral micronutrient supplements was beneficial.

Some patients had vitamin D deficiency alone, while others had a combination of deficiencies. These patients were more likely to suffer from musculoskeletal symptoms such as joint and bone pain, decreased mobility, muscle weakness, osteoporosis, and secondary hyperparathyroidism. Patients were given vitamin D supplements in a variety of routes, forms, and dosages, but underdosing and misdiagnosis were common problems.

Patients with zinc deficiency often developed dermatologic manifestations, and patients with vitamin B12 and folate deficiency had recurrent erythematous ulcers, dyspnea, and fatigue. Thiamine deficiency caused Wernicke encephalopathy and neurologic signs. Selenium deficiency was not isolated as the sole primary deficiency in any patient; it was present only as part of several deficiencies.

Pregnant and postpartum women predominantly developed deficiencies of vitamins A, K, B12 and zinc, which affected fetal growth and development.

Unbalanced diet, inadequate vitamin support, excessive alcohol consumption, delayed diagnosis, inadequate follow-up, lack of knowledge among health care providers, and inadequate patient education have been identified as factors contributing to vitamin deficiency and negative health outcomes after bariatric surgery.

The review highlights that some deficiencies, if not identified early, lead to permanent disability or even death, illustrating the importance of early detection and intervention. The study highlights the need for early identification and correction of deficiencies to prevent adverse patient outcomes.