April 22, 2016

Bariatric Surgeons Don't Do Nutrition

Bariatric surgeons are finding out that they have problems in many patients that they have operated on and this is the high risk of vitamin D deficiency and insufficiency among bariatric surgery patients. Both referring physicians and bariatric specialists need to take a greater role in personalizing vitamin D supplementation regimens in these patients.

Even most referring physicians aren't aware of the importance of early vitamin D intervention or may not be addressing the issue in the most effective manner. Even with the latest medical research, doctors specializing in bariatric surgery do not yet know the best vitamin D supplementation regimen for these patients. As a result, the referring physicians and bariatric specialists should be working together to closely monitor and tailor an individualized supplement regimen for each patient.

The best method of treating vitamin D malnutrition pre- and post-bariatric surgery is to deliver a higher daily dose of vitamin D and then adjust to the appropriate blood 25(OH)D readings, which will require personalized medicine and treatment from both referring physicians and bariatric specialists. Personalized vitamin D supplementation will prevent both under- and overtreatment in bariatric surgery patients and is likely also important for many other patient populations who are at risk for vitamin D deficiency, including people who have obesity or in those who are overweight.

Until recently, vitamin D deficiency after bariatric surgery was thought to be due to side effects of the procedure, i.e., poor absorption of fat-soluble nutrients. It has been determined now that vitamin D deficiency stems of pre-surgery malnutrition with up to 98 percent of bariatric surgery candidates having vitamin D deficiency. This malnutrition persists after surgery despite supplementation and weight loss, which theoretically releases vitamin D stored in the fat.

The primary concern over vitamin D deficiency is that the risk of deficiency is even greater after bariatric surgery when these patients may be less able to absorb vitamin D, and, thus, treatment before surgery may be more effective. Improving vitamin D status before surgery may also improve healing and shorten the length of stay in the hospital following bariatric surgery.

What is an optimized vitamin D level in a patient before or following bariatric surgery? According to the 2013 American Society for Metabolic and Bariatric Surgery guidelines, physicians should bring blood concentrations to greater than 30 ng/mL of 25-hydroxyvitamin D, the circulating form of vitamin D. The society recommends achieving these readings by delivering the standard daily dose of at least 3,000 IU, test the patient's blood, adjust the dose, test again and repeat until the patient's vitamin D readings are optimized. A physician may consider giving high doses of vitamin D -- 50,000 IU one to three times weekly or even daily -- if necessary for patients following surgery. The recommendations from the society sound like a ringing endorsement for personalized medicine.

A key consideration in vitamin D supplementation that physicians need to be aware of is the form of vitamin D given. Vitamin D3 is made in the skin during sun exposure and is found in over-the-counter supplements, whereas vitamin D2 is uncommon in the diet and found in high-dose prescription vitamin D supplements. In a meta-analysis of 57 studies, patients given vitamin D3 had an 8.08-ng/mL larger improvement in 25(OH)D readings over the same dose of vitamin D2 -- meaning vitamin D3 proved more effective. Despite this, many doctors inadvertently prescribe vitamin D2 to their bariatric surgery patients. Many doctors do not realize that writing a prescription for vitamin D will likely yield vitamin D2, and many also do not know the difference in effectiveness between these two forms. I recently showed that 87% of our bariatric surgery candidates prescribed high-dose vitamin D were given vitamin D2, despite that many patients only get a short window for preoperative treatment.

As for the appropriate dosing regimen, of 25 separate studies testing different regimens, none of these studies reported consistently optimized vitamin D readings in patients. These studies ranged from a daily multivitamin to high doses of vitamin D (50,000 IU monthly or weekly) and various combinations of daily and high doses. These findings from my recent review echo the society's recommendations, yet no studies giving dosages up to 5,000 IU daily reached optimized vitamin D readings universally. However, some patients did reach blood concentrations over the recommended 30 ng/mL. Would the best course of treatment really be to increase the standard dose for all, or should we only increase the dosage for those patients who are still below the recommended concentration?

With this discussion, I also have to wonder if the other vitamins and minerals are monitored and kept at the correct levels as I have seen other studies reporting deficiencies in other vitamins as well.

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