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When Losing Weight Means Losing Your Eyesight

Weight-loss surgery is an effective way to shed pounds, but it often comes with unexpected—and undiscussed—side effects.
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According to the Centers for Disease Control and Prevention (CDC), more than one-third of Americans are clinically obese. People who fall in this diagnostic category are more likely to have high blood pressure, high cholesterol, and type 2 diabetes, which means losing weight could be life saving. That, however, is not an easy task. While the CDC recommends a noble commitment to healthy eating and exercise, weight-loss surgery has been positioned as a more effective solution to the obesity problem in the US. But for one woman who was seeking to slim down in Texas, the procedure came with a scary side effect.


A case report recently published in the Journal of the American Medical Association outlines the terrifying scenario: The woman, in her 40s, visited an ophthalmology clinic after experiencing vision loss, eye pain, and eye lesions. She later found out that her eyesight problems were a symptom of a vitamin A deficiency. She developed the deficiency after she underwent a weight-loss—or bariatric—surgery known as a "duodenal switch," which reduces the size of the stomach and creates a bypass around the small intestine.

Generally, surgical weight loss has been lauded as a fix that actually works; there are several types of bariatric surgeries, and they work by restricting food intake. It is primarily women who choose to have the procedure. Where many people who want to shed and keep off weight find themselves stuck in a constant cycle of dieting and weight gain, patients who undergo bariatric surgery are said to enjoy sustained results. A 2012 study published in the New England Journal of Medicine even showed that participants who had the procedure were better able to manage their type 2 diabetes than those on medication alone. Seventy-five percent of participants who had gastric-bypass surgery went into remission, compared to zero percent on medical therapies.

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However, that weight loss surgeries can cause vitamin deficiencies—which can cause severe health effects—is not often discussed. The American Society for Metabolic and Bariatric Surgery, in fact, claims that it's a myth. The ASMBS concedes that the procedure increases the risk of nutrient deficiencies, but adds that these negative effects can be counteracted with supplements. "Health problems due to deficiencies usually occur in patients who do not regularly follow-up with their surgeon to establish healthy nutrient levels," the association claims. But independent reports say that vitamin deficiencies—including B6, folate, vitamin C, and vitamin A—are inherently common. While "[b]ariatric surgery can be effectively used to achieve sustainable weight-loss in morbidly obese patients," a 2012 study on vitamin absorption after bariatric surgery concluded, "it simultaneously brings forth important functional consequences on nutrient deficiencies and drug absorption that clinician's [sic] must be aware of."

Troublingly, another study found that "nutritional deficiencies are unrecognized in approximately 50% of patients who undergo gastric bypass surgery." In 2008, a woman who previously had bariatric surgery was hospitalized after experiencing rapid heartbeat, dehydration, low blood pressure, and weakness. It was only after she collapsed that the ultimate cause was found: a thiamine deficiency. And in the case of the Texas woman who experienced vision loss after she had the procedure, supplements didn't prevent her from ultimately having a vitamin deficiency. Kyle Kirkland, who authored the case report, told CBS that the patient had been taking a multivitamin but that it "was not enough to keep her from getting severe vitamin A deficiency," which is otherwise rarely seen in developed countries. "Oral vitamin A was not enough to reverse [her vision loss]," Kirkland told Broadly in an email. "[She had to] receive vitamin A through an IV."

One study, which followed up with patients four years after they had bariatric surgery, found that 65 percent of patients experienced a vitamin A deficiency within four years of undergoing a biliopancreatic diversion—one type of the surgery—with and without the duodenal switch procedure.

This all sounds bad—but what does it mean? "Vitamins are primarily absorbed in the small intestine," Kirkland explained. "Bariatric procedures such as [the] duodenal switch bypass a significant portion of the small intestine to induce weight loss." As a result, vitamin absorption is also bypassed. "Patients should be aware of the possibility that oral supplementation may not be sufficient to prevent vitamin deficiencies."

Although there have been several reports of vision loss following various bariatric procedures, the Texas woman is the second reported case after the duodenal switch.