The Positive and Negative Effects of Taking Antioxidants
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SUSAN DENTZER: Many Americans have long believed in the helpful powers of substances loosely called dietary antioxidants.
MAN: Most of the time when I feel a cold coming on, I load up with Vitamin C.
SUSAN DENTZER: Some of these substances include Vitamins C and E., found in fruits like citrus fruits and leafy vegetables, as well as the nutrients beta-carotene, found in carrots, and selenium, found in seafood and meats. Although these substances actually have a range of nutritional benefits, they’re often also identified as antioxidants. That’s because they also decrease the ill effects that certain highly reactive molecules of oxygen and nitrogen have in the body. Some research has shown that the resulting damage could play a critical role in illnesses such as cardiovascular disease and cancer.
As a result, the reasoning went, consuming extra levels of antioxidants could actually thwart or reverse these damaging effects on cells. And it’s provided a powerful boost to the $14 billion a year nutritional supplement industry. But for several years now, a growing body of evidence has cast doubt on the notion that antioxidants protect the body against illnesses ranging from colds to cancer.
So today, a panel appointed by the National Institute of Medicine unveiled a new set of dietary recommendations. The Institute noted that the range of studies to date provide only limited support for the notion that antioxidants protects against illness. It added, however, that diets rich in fruits and vegetables are associated with lower risks of cancer and heart disease. But it said it isn’t at all clear that the antioxidant property of these substances provides the benefits.
What’s more, the panel said people could generally obtain sufficient levels of these foods and the nutrients in them by eating a well-balanced diet. The panel also warned specifically against possible dangers of consuming very high doses of antioxidants. For ample, it noted a higher, not lower, incidence of lung cancer in smokers who were taking extra-high doses of beta-carotene. So the panel set new upper limits on the amounts of these substances that were safe to consume; in the case of Vitamin C, a total of 2,000 milligrams a day.
GWEN IFILL: Joining us now are Dr. Susan Mayne, an associate professor of Epidemiology and Public Health at Yale University; she was a member of the committee that drafted today’s report. And John Cordaro, president and CEO of the Council for Responsible Nutrition, a trade association representing 110 major manufacturers of dietary supplements and ingredients.
Doctor Mayne, in your opinion what is the most significant finding of the study?
DR. SUSAN MAYNE, Yale University: I think the most significant finding in my mind is that we reviewed an enormous amount of scientific literature looking at whether or not these nutrients in high doses could protect again chronic diseases. And, as you’ve said already, I think our major conclusion is at there is not evidence at this time supporting a role for higher than average intake of these nutrients for the prevention of chronic diseases.
GWEN IFILL: Does that mean that it is hopeless to be taking these kinds of supplements assuming it’s going to help prevent — or does it mean that you just haven’t proven that?
DR. SUSAN MAYNE: I think that is an important point. At this point the scientific evidence is mixed. For example for some of these possible indications there were promising findings, but certainly one study or one small indication was not enough to make any kind of a policy recommendation for the general population. So we did set out a number of a very important research recommendations to support further clinical trials and other studies to get a better hand hold on what these nutrients can and cannot do.
GWEN IFILL: Mr. Cordaro as a representative of the vitamin supplement industry, what was the most significant finding for you in that report?
JOHN CORDARO, Council for Responsible Nutrition: I think the most significant find is that this was a positive step for consumers, because, number one, is that the evidence does show that there is some promise. We agree with the general finding that the evidence may not be conclusive enough to set what the specific amounts of the doses that one should consume are, and the Council for Responsible Nutrition would encourage our member companies, the federal government, and the research community to focus on those areas where we need to get more answers so we can provide more conclusive information to consumers.
GWEN IFILL: In your opinion, if a patient has been told by his or her doctor that perhaps Vitamin E would be a good way of insurance against Alzheimer’s down the road, and had been taking Vitamin E daily or weekly, would you say that person should continue to keep doing that?
JOHN CORDARO: I would say if a doctor told a patient to do that, I certainly wouldn’t stand in the way of what the doctor has said. I would say that for the general population, that one of the very significant findings of this report was the establishment of upper safe limits for these antioxidant nutrients.
GWEN IFILL: Which means what?
JOHN CORDARO: Which means that the National Academy of Sciences for the first time has provided an endpoint for consumers to understand that one should not consume these antioxidants beyond that level. It’s not that they would necessarily be harmed, but that the data that is available suggests that there could be some risk.
GWEN IFILL: Dr. Mayne, the same question to you. If someone is taking these kinds of vitamins with the assumption that perhaps it will help or at least it won’t hurt them, would you say they should stop taking them now, based on your findings?
DR. SUSAN MAYNE: I think it would depend upon what the person was taking it for, whether they were in consultation with their physician, and what the doses are. And again with regard to Vitamin E, we have set an upper limit for Vitamin E. And the studies that you were referring to with regard to Alzheimer’s, etcetera, those studies used doses greatly in excess of the upper limit. So if someone is simply taking doses with the hope of preventing some of these diseases, if they are below the upper limit of intake, I’m less concerned. If they are above it, then I would certainly want them to be doing that in consult with an physician even more ideally in the setting of a research intervention study.
GWEN IFILL: You talk about the upper limits for dosage. How do you know what is too much?
DR. SUSAN MAYNE: Well, that was part of the panel’s report. What the upper limits say is what is the upper limit that people can routinely take, that is, on a daily basis without increasing the likelihood of having some adverse events occur? So this is a dose that is set on the probability of not having an adverse event occur.
GWEN IFILL: For example, what is an adverse event that would occur as a result of one of these vitamins that are part of your study?
DR. SUSAN MAYNE: For each nutrient there was a different adverse event that we looked at. In the case of Vitamin E, it is the possible increase in the risk of hemorrhage or hemorrhagic stroke, so the upper limit was set for Vitamin E at 1,000 milligrams per day in order to avoid the likelihood of having hemorrhage be an adverse effect of too much Vitamin E.
GWEN IFILL: Mr. Cordaro, another finding of the report was so much of the vitamins which are provided in supplements can be found in a regular average balanced North American diet, so why take supplements at all?
JOHN CORDARO: It’s a good question, Gwen. The Council for Responsible Nutrition has always recommended that the consumer look to food first to try to get the nutrients that they need. Unfortunately, most of us do not select our foods in a way that allows us to get the nutrients that we need. So we have always viewed supplements as exactly that, as a complement or as an adjunct to foods that we should consume.
GWEN IFILL: Is that so, Dr. Mayne, are we really not getting all the vitamins we should for a normal diet?
DR. SUSAN MAYNE: Again it depends upon the nutrient. It depends upon the population. With some nutrients we do quite well. For example, for nonsmokers, the vast number of the population consumes the RDA level of Vitamin C already. However, with regard to smokers, they actually have a higher requirement for Vitamin C, and the data indicate that many smokers in the U.S. do not achieve the required intake levels through either diet and or supplements.
GWEN IFILL: Even though the headline seems that supplements may not be as necessary as we thought, you still recommend higher doses of E and C. Why is that?
DR. SUSAN MAYNE: The reasons for the two specific nutrients… With regard to Vitamin E, the data that has accumulated since the last time recommendations were issued — which was in 1989 — indicates that human requirements are higher than we previously thought. So you are correct. The Vitamin E RDA has increased and actually has increased rather substantially. With regard to Vitamin C, the RDA has also gone up. The previously RDA was 60 milligrams and it’s now up to 75 milligrams for women and 90 for men. There are some increases, and the reason being that the evidence supports a slightly higher intake level as a target for the American population based upon current data.
GWEN IFILL: And what does that mean, the higher intake level? Do you think that is good news for vitamin supplements, the fact that they are recommending any increases at all?
JOHN CORDARO: Yes, we do, because the Council for Responsible Nutrition has tried to be a science-based association. And we believe that we should be able to follow the science, whether it is at one end, or talking about upper limits, or where it’s talking about expanding or increasing the RDA’s for individual nutrients.
GWEN IFILL: Mr. Cordaro, there are so many health claims involving different vitamins, Vitamin A to help eyesight, I think, and Vitamin E is supposed to prevent prostate cancer and Vitamin C is supposed to help heart disease. Have all of these claims maybe outpaced the actual good that these supplements can do?
JOHN CORDARO: When we talk about claims or providing information to the consumer, a lot of the information that the consumer receives is either through… whether it’s through television or print media, but the area that can be held accountable is the manufacturer of a dietary supplement. If a manufacturer puts a claim on a label or uses it in advertising, there are very strict regulations. The U.S. Food and Drug Administration and the U.S. Federal Trade Commission requires that the manufacturer substantiate those claims.
GWEN IFILL: Dr. Mayne, the bad news for at least one vitamin supplement was beta carotene in this study. What is wrong with beta carotene? Is it just over-promised?
DR. SUSAN MAYNE: With regard to beta carotene we have lots of observational data that showed that people who eat more beta carotene from foods have a lower incidence of many chronic diseases. But beta carotene comes in the form of fruits or vegetables, and it’s hard to know is it the beta carotene or the fruits and vegetables other components? So there were several randomized clinical trials done to test whether it was really the beta carotene or is there something else in the fruits and vegetables that maybe protected, and as you mentioned previously, to our great surprise, two of those studies actually found that people who took high dose beta carotene supplements and who are smoking have more lung cancer, not less. So the clinical trials have not yet proven there is any benefit to supplementing with beta carotene. However, consuming more beta carotene, however, consuming more beta carotene from food, i.e., fruits and vegetables, was strongly endorsed by the panel.
GWEN IFILL: But as Mr. Cordaro just mentioned, people get their information about these kinds of supplements from so many sources, and beta carotene has certainly seemed to be one of the things we heard the best things about. Should people just be pulling back?
DR. SUSAN MAYNE: The recommendation from the panel is that beta carotene supplements are not advocated, and it’s because of the findings of possible increase in lung cancer in two major trials. It was not observed in a third but was seen in two — countered by the fact that there hasn’t been any evidence of benefit. So the recommendation is that beta carotene supplements are not advocated by the panel at this point for the prevention of chronic diseases.
GWEN IFILL: But Americans, Dr. Mayne, love the idea of a pill as a cure-all. Is this a caution flag?
DR. SUSAN MAYNE: It is a caution flag. I think it’s a caution flag to the whole nutrition community. Most people always believe that a little bit of a vitamin helps, if a little helps you, a lot must be better. And these large intervention studies involving more than 50,000 people in total have clearly indicated that there may not be… that assumption may not be correct; that high doses may, in fact, cause them harm.
GWEN IFILL: At what point, Mr. Cordaro, do people not just take it because it can’t hurt?
JOHN CORDARO: I mean on the point about beta carotene… I think that is a point that is worth underscoring. The responsible segment of the dietary supplement industry does not market single entity beta carotene capsules for the purpose of reducing a risk of disease. Beta carotene does have a very useful role as a mixture, or as a part of a carotenoid package as a substitute for Vitamin A, so that does have a very special… continuing special role to play.
GWEN IFILL: But what about the notion that you can’t hurt if you take too much?
JOHN CORDARO: Well, that is not a good notion. The reality is that the message that the American public should get is that they should look to food to try to get as much of a balanced diet as they can, to supplement with key nutrients, to help provide the extra nutrients that they are not getting, and that when they are using a dietary supplement, they should use the product in accordance with the label and they should not assume if a little is good, a little bit more is going to be better.
GWEN IFILL: Mr. Cordaro and Dr. Mayne, thank you very much.
JOHN CORDARO: Thank you.