martes, 17 de diciembre de 2013

TACT: No CVD Benefit With High-Dose Multivitamins

MIAMI BEACH, FL — A high-dose regimen that includes 28 vitamins and minerals given to stable patients with a history of MI does not reduce their future risk of cardiovascular events, according to the results of a new analysis[1].
The results, from the second arm of the 2x2 factorial Trial to Assess Chelation Therapy (TACT), funded by the National Heart, Lung, and Blood Institute (NHLBI) and National Center for Complementary and Alternative Medicine (NCCAM), were first presented at the American College of Cardiology 2013 Scientific Sessions and are now published online December 16, 2013 in the Annals of Internal Medicine.
The trial showed no benefit of multivitamin therapy in 1708 patients who received the supplements.
Stop wasting money on vitamin and mineral supplements.
"I'm a completely conventional cardiologist," Dr Gervasio Lamas (Mount Sinai Medical Center, Miami Beach, FL), the lead investigator of TACT, told heartwire . "I don't prescribe vitamins, and I tell my patients not to waste their money on them. But when I think of vitamin, I think of a microgram or a milligram, a nutritional supplement, which is used to replete a nutritional deficiency. But when you get these vitamins and minerals and you bring these up to very high dosages, and then you mix them, I think you do have unpredictable effects that can't be judged based on first principles."
For Dr Eliseo Guallar (Johns Hopkins Bloomberg School of Public Health, Baltimore, MD), Dr Saverio Stranges (University of Warwick, Coventry, UK), Dr Cynthia Mulrow (Annals of Internal Medicine, Philadelphia, PA), and Drs Lawrence Appel and Edgar Miller (Johns Hopkins School of Medicine, Baltimore, MD), the addition of the TACT data to the literature provides yet more evidence that the time has come to "stop wasting money on vitamin and mineral supplements."
"Although available evidence does not rule out small benefits or harms or large benefits or harms in a small subgroup of the population, we believe that the case is closed—supplementing the diet of well-nourished adults with (most) mineral or vitamin supplements has no clear benefit and might even be harmful," state the editorialists. "These vitamins should not be used for chronic disease prevention. Enough is enough."
Studying Mega Doses of Vitamins Used With Chelation
As reported by heartwire , the other, more controversial arm of the TACT trial found investigators and other experts at a bit of a loss when the study showed chelation therapy, an alternative-medicine mainstay, modestly improved clinical outcomes in patients after an acute MI. The difference in the primary end point—a composite of all-cause mortality, MI, stroke, coronary revascularization, and hospitalization for angina—reached the trial's specified threshold for statistical significance.
In this study, the TACT investigators randomized patients 50 years of age or older who had an MI at least six weeks prior to treatment with high-dose multivitamins and multiminerals, including vitamins A, C, and E, as well as selenium and magnesium, or to placebo.
Lamas explained that the multivitamins and multiminerals used in their analysis were standard doses used by centers practicing chelation therapy. Patients undergoing the controversial treatment were given large doses of oral vitamins and minerals, nearly all of which exceed the daily recommended values. For example, 1200 mg of vitamin C, 25 000 IU of vitamin A, 400 IU of vitamin E, 200 mg of niacin, and 800 µg of folate were prescribed, and these amounts all exceed the daily recommended dosages.
Adherence rates were low in the trial, however, with 46% of patients discontinuing the treatment during the study. In total, 76% of participants completed one year of treatment and only 47% of participants in the active-treatment arm completed three years. Dropout rates were also high, with 17% of patients withdrawing from the study.
The primary end point occurred in 27% of patients in the multivitamin arm and 30% of patients in the placebo group. In terms of risk reduction, there was a nonsignificant 11% reduction in the primary end point (TACT was powered for a 25% reduction in risk). Based on the data, Lamas said patients should not be taking vitamin or mineral supplements for cardiovascular-disease prevention


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