Friday, October 14, 2011

Is Zinc Supplement really required after Gastric Bypass Surgery ?

Plasma zinc levels drop as absorption of the mineral decreases after Roux-en-Y gastric bypass (RYGBP) surgery, according to findings published in the October Issue of the American Journal of Clinical Nutrition.

"RYGBP decreases intestinal capacity to absorb zinc and increased amounts of this element should be used," Dr. Manuel Ruz from the University of Chile in Santiago told Reuters Health in an email. "We are not sure what the right amount is at this moment, but certainly it should be somewhere around 25-30 mg/d on a regular basis." Dr. Ruz and colleagues assessed zinc status and zinc absorption before and 6, 12 and 18 months after RYGBP in 67 women.

The women were randomly assigned to two groups: group A received a standard vitamin and mineral supplement (with 7.5 mg/d elemental zinc), and group B received a specially designed vitamin and mineral supplement that provided at least the recommended daily allowance of selected nutrients (with 15 mg/d elemental zinc). Both groups also received daily calcium and vitamin D supplementation.
he level of zinc supplementation had no effect on any of the indices of zinc status, so the groups were combined for further analyses.

Plasma zinc, erythrocyte membrane alkaline phosphatase activity, and the rapidly exchangeable zinc pool (EZP) were significantly lower 12 and 18 months after RYGBP. Erythrocyte metallothionein remained unchanged throughout the study, and hair zinc unexpectedly increased at 6 and 12 months (but not at 18 months) after surgery.Zinc absorption decreased from 32.3% before surgery to 13.6% by 6 months after surgery and recovered slightly to 21.0% by 18 months.

Dr. Ruz said zinc status should be measured routinely after RYGBP."Unfortunately, there are not good and reliable methods to do so. However, repeated (every 3 or 6 months) serum or plasma zinc could help. It is important to avoid the presence of inflammation when analyses are carried out (plasma zinc is reduced under these conditions)."

"Chronic high zinc intakes can be toxic," Dr. Ruz cautioned. "In fact, the immune system is affected. Therefore, my guess is that supplements should not exceed 50 mg/day. We don't have experimental data yet to be sure about the upper limit of intake under these conditions, so the 50 mg/d should be considered just an approximation."He said his group is currently studying the effects of higher-dose zinc supplements after RYGBP.

"Besides we are looking into the effects of other types of bariatric surgeries, particularly sleeve gastrectomy," Dr. Ruz added. "Results are expected to be published in early 2012."

Source - Medscape news website

1 comment:

  1. Thank you for the detailed article. I have been taking gastric bypass supplement after my surgery and they contain the required levels of zinc.