U.S. Dietary Guidelines for Vitamin E
Tuesday, February 17th, 2009WASHINGTON, D.C. (November 10, 2004) – Despite the literally thousands of studies on vitamin E, many confirming its positive effects on cardiovascular health and other conditions, an article published today in the Annals of Internal Medicine that studied just a handful suggests that “high-dose” vitamin E (400 international units (IU) or more) is associated with a greater risk of dying.
Although the researchers themselves acknowledged the limitations of their study when applied to most healthy people, they have nevertheless called for a reduction in U.S. dietary guidelines for vitamin E, which currently recommend an upper limit of 1,500 IU.
The research, which analyzed clinical trial data from 19 studies, focused on nine that involved dosages of vitamin E over 400 IU. Most of the patients in the studies were over 60-years of age and had chronic health conditions, such as heart disease and Alzheimer’s. The reported increased risk of deaths associated with higher doses of vitamin E was only slightly higher than the risk among those not taking the supplement. The studies reviewed, some of which were more than 10 years old, were of varying quality and contained a wide range of dosages.
“This is arm chair science at its worst,” said David Seckman, NNFA’s executive director and CEO. “Researchers are well aware that casting doubt on any product that has had overwhelmingly positive findings is a formula for getting noticed. Unfortunately, many in the press are all too willing to lend credence to research that is not conclusive.”
For more information on vitamin E, including its health benefits, clinical applications and other science-based findings, go to: http://www.supplementinfo.org/.
http://www.naturalproductsassoc.org/site/
News2?abbr=pc_&page=NewsArticle&id=5229
Vitamin E Trials ‘Fatally Flawed’
ScienceDaily (Sep. 26, 2007) — Generations of studies on vitamin E may be largely meaningless, scientists say, because new research has demonstrated that the levels of this micronutrient necessary to reduce oxidative stress are far higher than those that have been commonly used in clinical trials.
In a new study and commentary in Free Radical Biology and Medicine, researchers concluded that the levels of vitamin E necessary to reduce oxidative stress — as measured by accepted biomarkers of lipid peroxidation — are about 1,600 to 3,200 I.U. daily, or four to eight times higher than those used in almost all past clinical trials.
This could help explain the inconsistent results of many vitamin E trials for its value in preventing or treating cardiovascular disease, said Balz Frei, professor and director of the Linus Pauling Institute at Oregon State University, and co-author of the new commentary along with Jeffrey Blumberg, at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University.
“The methodology used in almost all past clinical trials of vitamin E has been fatally flawed,” said Frei, one of the world’s leading experts on antioxidants and disease. “These trials supposedly addressed the hypothesis that reducing oxidative stress could reduce cardiovascular disease. But oxidative stress was never measured in these trials, and therefore we don’t know whether it was actually reduced or not. The hypothesis was never really tested.”
The level of vitamin E that clearly can be shown to reduce oxidative stress, new research is showing, is far higher than the level that could be obtained in any diet, and is also above the “tolerable upper intake level” outlined by the Institute of Medicine, which is 1,000 I.U. a day. OSU researchers are not yet recommending that people should routinely take such high levels, but they do say that controlled clinical trials studying this issue should be aware of the latest findings and seriously consider using much higher vitamin E supplement levels in their studies.
In lab, animal or human studies, there’s evidence that vitamin E can reduce oxidative stress, inhibit formation of atherosclerotic lesions, slow aortic thickening, lower inflammation, and reduce platelet adhesion. Some human studies using lower levels of vitamin E supplements, such as 100 to 400 I.U. a day, have shown benefits in reducing cardiovascular disease risk, and others have not. An underlying assumption was that these levels were more than adequate to reduce oxidative stress, since they far exceeded the “recommended dietary allowance” or RDA for the vitamin, a level adequate to prevent deficiency disease.
“What’s now clear is that the amount of vitamin E than can conclusively be shown to reduce oxidative stress is higher than we realized,” Frei said. “And almost none of the studies done with vitamin E actually measured the beginning level or reduction of oxidative stress.”
Proper studies of vitamin E, researchers say, must be done carefully and take into account the newest findings about this micronutrient. It’s now known that natural forms of the vitamin are far more readily absorbed than synthetic types. It’s also been discovered that supplements taken without a fat-containing meal are largely useless, because in the absence of dietary fat vitamin E is not absorbed.
Some clinical trials may wish to study the long term effect of vitamins on healthy individuals. But if a clinical trial seeks to learn the value of reducing oxidative stress, they should select patients in advance for those who have high, measurable oxidative stress — often people who are older or have a range of heart disease risk factors, such as obesity, poor diet, hypertension or other problems. Cognizance should also be taken of people with health issues that may further increase their vitamin needs, such as smokers.
“A pill count simply isn’t enough to determine the value of vitamin E,” Frei said. “We need to select people for trials properly, make sure they are taking the right form of the vitamin, at the right levels and at the right time, and then verify the metabolic results with laboratory testing.”
“Only when we do these studies right will we answer questions about the value of vitamin E in addressing cardiovascular disease,” he said. “So far we’ve been flying blind.”
A parallel, Frei said, would be presuming to test the value of a statin drug, which lowers cholesterol, without ever measuring cholesterol levels in the test subjects, neither at the beginning nor at the end of the study. Such trials would be ridiculed in the science community.
So far, that’s the way vitamin E has been studied.
The use and intake of vitamins, experts say, has traditionally been thought of in terms of overt deficiency — for example, not enough vitamin C causes scurvy. Much less research has been done on the levels that can help create optimum health. The issue is of special importance with modern populations that have very different diets, activity levels and increased lifespan, and are dying from much different causes — predominantly heart disease and cancer — than people of past generations. Adapted from materials provided by Oregon State University, via EurekAlert!, a service of AAAS.
http://www.sciencedaily.com/releases/2007/09/
070923193622.htm
New JAMA Study on Ginkgo Biloba and Alzheimer’s ‘Misses the Boat Entirely’
Tuesday, November 18, 2008
Study Too Limited and Ignores Critical Risk Factors, Says Natural Products Association
November 18, 2008, Washington, DC — A new
“This study is not irrelevant, but it can not be used to make broad conclusions about Ginkgo biloba and the general population. In fact, it misses the boat entirely in two critical areas. One, it looks exclusively at people almost 80 years old who are far more likely to have Alzheimer’s, while ignoring those in middle ages, where the risk for developing the disease rises quickly and prevention could best be analyzed. Two, it excludes completely any consideration of the strong and established role that family history plays with Alzheimer’s. You can’t do a study on the weather without looking at wind and rain,” said Daniel Fabricant, Ph.D., vice president for scientific and regulatory affairs at the Natural Products Association.
“This study is also in direct contrast to other research. Unfortunately, there is still no proven treatment to prevent Alzheimer’s, but reputable research has shown that Ginkgo biloba can play a constructive role in improving the symptoms related to this debilitating disease and possibly delaying its onset,” said Fabricant.
BACKGROUND: According to the National Institute on Aging, age is the most important known risk factor for AD. The risk of developing the disease doubles every 5 years over age 65. Several studies estimate that up to half the people older than 85 have AD. These facts are significant because of the growing number of people 65 and older. More than 34 million Americans are now 65 or older. Even more significant, the group with the highest risk of AD—those older than 85—is the fastest growing population group in the country.
A 1997 study in the U.S. suggested that a Ginkgo extract may be of some help in treating the symptoms of AD and multi-infarct dementia, but no evidence exists that Ginkgo biloba will prevent AD.
Research shows that risk for the disease becomes significant in middle age for most of the population, yet this study ignores that completely.
http://www.naturalproductsassoc.org/
site/News2?abbr=pc_&page=NewsArticle&id=10219
Stevia Hits the Big Time
The low-calorie sweetener hailed as “natural” is coming to a grocery store shelf near you. Coke will start delivering stevia-sweetened Odwalla Mojito Mambo and Odwalla Pomegranate Strawberry nationwide this week and plans to introduce Sprite Green in New York and Chicago before the end of the year. Pepsi is expected to follow with SoBe Lifewater in three flavors (black and blue berry, Fuji apple pear and yumberry pomegranate) as well as a 50% reduced calorie orange juice, Trop50. Both use Cargill’s Stevia Sweetener, branded Truvia.
The news is heating up the financial markets: will the natural low-cal sweetener sweeten profits as well? But what interests us is the safety of the new ingredient. The FDA is expected to give stevia-derived sweeteners the status of generally recognized as safe (known as GRAS in the industry), but is GRAS the same as SAFE?
Is Generally Recognized as Safe the Same as Safe?
GRAS is a short-cut to get approval for an ingredient without going through the usual array of studies on the safety and health effects intended to prove an ingredient safe. This short-cut saves industry a lot of money and potential test animals a lot of suffering, so in general it is reasonable that the agencies responsible for food safety have a method to approve ingredients based on the weight of evidence for chemicals which have been in use for many years.
GRAS has another benefit too: advocates of stevia-based sweeteners feared that sweetener manufacturer Cargill would get an approval exclusive to their highly purified version of stevia sweetener, called Truvia. But GRAS status should allow competitors to enter the market. Some stevia based sweeteners and even softdrinks are available on the market now, being marketed under the “dietary supplement” loophole, which allows sale of products with less safety testing.
But if stevia is banned in Europe and not approved for use as a food additive in the US, where is FDA getting information as a basis to decide that stevia is safe? The stevia plant has been used by inhabitants of its native growth zones for centuries. Of course, it has been used as a sweetener, but some tribes using stevia believe chewing the leaf is an effective birth control method. Which leads to obvious questions: if the plant can reduce fertility, it is certainly having health effects.
The Good News and the Bad News
Studies have suggested that stevia sweeteners can have cancer-causing effects and mutagenic effects, as well as reducing male fertility. But all the news is not bad. Preliminary study results also suggest that stevia may have positive effects beyond weight control, including vasodilation (an effect that can be therapeutic for high blood pressure) and improved regulation of blood glucose levels (possibly beneficial in relation to diabetes).
More recent human experience suggesting stevia based sweeteners are safe comes out of Japan, where the natural low calorie stevia sweeteners have been preferred over artificial sweeteners for the past four decades. Food standards agencies in Australia and New Zealand have also published stevia safe intake levels that equate to drinking two cans of diet softdrink per day (see the link for the basis for this calculation).
As is the case with trans-fats and high fructose corn syrup, scientists are about to get a lot more data for continuing studies on the safety of this sweetener. The best advice is moderation in all things, and remember that there are risks with artificial sweeteners as well. Stevia sweeteners offer an “all natural” option for people when the health risks from obesity outweigh other concerns.
http://www.treehugger.com/files/2008/12/coke-truvia-stevia-fda-safe-pepsi.php