Navigation Links
Vitamin E's lack of heart benefit linked to dosage
Date:8/22/2007

Nashville (Tenn.) - The reported failure of vitamin E to prevent heart attacks may be due to underdosing, according to a new study by investigators at Vanderbilt University Medical Center.

The findings, published early online in Free Radical Biology and Medicine, suggest that these earlier studies all had a fundamental flaw the doses used werent high enough to have a significant antioxidant effect. In fact, no studies have ever conclusively demonstrated the dose at which vitamin E can be considered an antioxidant drug, the researchers report.

Oxidant injury, or oxidative stress, occurs when highly reactive molecules called free radicals attack and damage cellular proteins, lipids (fats) and DNA. Free radicals, which are byproducts of normal metabolism, are produced in excess in certain disease states, including heart disease.

Epidemiological data and animal studies suggested that antioxidant compounds like vitamin E, vitamin C and beta-carotene might offer some protection against heart attack in individuals at risk.

But subsequent controlled clinical trials of vitamin E which showed little to no benefit from the vitamin stymied that hope.

Multiple human trials looking at the effect of vitamin E supplementation on coronary events and atherosclerosis have all failed, said Jack Roberts, M.D., the T. Edwin Rogers Professor of Pharmacology, professor of Medicine, and lead author on the study.

Were talking about trials that examined quite high doses, added Jason Morrow, M.D., F. Tremaine Billings Professor of Medicine & Pharmacology and chief of the Division of Clinical Pharmacology. Short of a couple of studies, there was no benefit in terms of prevention of cardiovascular events and deaths.

These results caused many to discount vitamin E supplementation as a cardioprotective treatment, but Morrow and Roberts suspected that the studies had been poorly designed. All of the trials simply gave a dose of vitamin E and looked for end points such as heart attack occurrence. But Morrow and Roberts found a critical piece of information missing.

All of these studies were designed in a way that they never assessed the ability of the dose of vitamin E tested to effectively reduce oxidant stress, Morrow said.

Without determining whether the dose of vitamin E given was exerting sufficient antioxidant effects, the previous clinical trial results were flawed, the researchers said.

In the new study, Morrow and Roberts determined the optimum antioxidant dose of vitamin E using an assay they developed to measure compounds formed by oxidative stress processes, called F2-isoprostanes. This measure, said Roberts, has been independently validated as the best measure of oxidative stress status in vivo.

The researchers first determined how long it took for a very high dose of vitamin E 3200 IU/day to suppress oxidative stress in individuals at risk for cardiovascular disease.

To their surprise, it took 16 weeks for this dose which is more than 100 times the recommended daily intake and about four times higher than doses used in most previous clinical studies to maximally suppress F2-isoprostane formation.

In another group with similar cardiovascular risk factors, the researchers administered varying doses (0, 100, 200, 400, 800, 1600, and 3200 IU/day) over the 16-week period to find the minimum effective dose.

They found that it was necessary to give at least 1600 IU per day to cause a significant reduction in oxidative stress twice that used in some of the previous clinical trials.

It was clear that large doses and doses in excess of what all clinical studies had used were necessary, Morrow said.

Even with this massive dose of vitamin E, you only observe a 50 percent reduction in F2- isoprostanes, added Roberts. So in my opinion, vitamin E is not the spiffy antioxidant everybody thinks it is its a pretty poor antioxidant.

Because the long-term safety of such high doses is unknown, we are not touting taking vitamin E in large doses, Morrow said. We are saying that, in the design of clinical trials, one needs to have good surrogate biochemical markers.

Based on their findings, the investigators suggest that measures like F2-isoprostane measurement should be incorporated into any future studies of antioxidants in atherosclerosis prevention.

And since oxidative stress has been linked to numerous other diseases, including Alzheimers disease, Morrow suggests that F2-isoprostane measurement really ought to be incorporated into studies assessing disease prevention by antioxidants in general.


'/>"/>

Contact: Craig Boerner
craig.boerner@vanderbilt.edu
615-322-4747
Vanderbilt University Medical Center
Source:Eurekalert

Related medicine news :

1. Vitamin B12 can help in detecting cancers
2. Vitamins-The answer to Heart Disease?
3. Vitamin E, the latest warrior against diabetes
4. Vitamin Shields Brittle Bones
5. Beer vitamin protects heart
6. B Vitamin protects and lowers toxicity of Arthritis Drug
7. B Vitamin Supplementatoin Saves Money and Lives
8. Eat Vitamin C and stay young
9. Vitamin C for the heart
10. Vitamin B for Hepatitis
11. Vitamins reduce pre-eclampsia
Post Your Comments:
*Name:
*Comment:
*Email:
(Date:5/31/2016)... ... ... The successful implementation of “lean manufacturing” in various fields has inspired many ... challenges compared to manufacturing environments. , In order to provide a way to ... the Lean Lab Checklist . This checklist will help users gain an overview ...
(Date:5/31/2016)... ... May 31, 2016 , ... Like jewels in a ... already know – London is home to Ontario’s leading day spa and one of ... Fayez Tamba began with a unique concept to combine spa services with hair ...
(Date:5/31/2016)... ... ... The Global Wellness Summit (GWS), an annual conference for international ... travel, spa and beauty in Europe. The organization asked its partner experts in Europe ... researchers - to forecast where wellness is headed in Europe. Predictions range from European ...
(Date:5/31/2016)... CA (PRWEB) , ... May 31, 2016 , ... WaterField ... for digital-minded professionals, announces the waxed-canvas and leather Duo Dopp Kit , the ... waxed canvas or ballistic nylon, the Duo is smartly designed for Dad’s ...
(Date:5/31/2016)... ... , ... In his latest video, renowned AstroNumerologist Jesse Kalsi ... presidential candidate Donald Trump as an example, Kalsi describes the way AstroNumerology conveys ... adding numbers up,” says Kalsi. “It is about looking at each individual number, ...
Breaking Medicine News(10 mins):
(Date:5/31/2016)... India , May 31, 2016 ... boomer population coupled with surging prevalence of deaths from chronic ... By Application, By Region, By Country): Opportunities and Forecasts (2016-2021) ... By Application Orthopaedic, Cardiovascular, Plastic Surgery, Wound Care); By Region-North ... - US, UK, Germany , ...
(Date:5/31/2016)... ZIONA, Israel , May 31, ... medicine company utilizing its proprietary plant-based rhCollagen technology for ... authorization from the Chief Scientist of Israel,s ... of its NIS 12 million development project for 2016. The ... higher than last year,s authorized grant, which totaled NIS ...
(Date:5/31/2016)... , Isansys  Lifecare, a new generation digital healthcare company, ... patient monitoring platform, as it ships more systems to hospitals in ... Scotland and Norway , ... earlier this year, is now being used in ground-breaking clinical ... new technology significantly enhances the user experience and provides higher ...
Breaking Medicine Technology: