Review, Inside New Zealand "documentary" Are Vitamins Killing You?
It confirmed what I've always known, that TV cannot report responsibly on inherently complex matters of science or history. Instead of explaining things scientifically in the detail required to give an honest version of events, time is wasted on trivia, soundtracks, action shots that add nothing to the data presented, and the data itself is so often wrong. Thus, last night we were taught that vegetables are a source of vitamin D, that vitamin B is a single vitamin, with the chemical structure of thiamine and a single list of positive and negative effects, that there is no difference between retinol and beta carotene, that vitamin deficiency syndromes in New Zealand are too rare to be worth mentioning, and so on.
Potential pro-oxidants in supplement form are excesses of iron and copper. One of the participants in the program was supplementing iron without a diagnosed deficiency, but her iron levels were not taken, because the show was about vitamins!
Thus a chance to warn the audience about the proven pro-oxidant dangers of high iron levels was missed.
Much was made of a statistical analysis of 60 antioxidant papers (chosen from the many hundreds available) called the 2008 Cochrane Collaboration, yet we were given no detail about what kind of data this actually represented. If we had been told that most of the negative statistics for vitamin E came from a single 28 day, very high-dose trial in terminal cancer patients, and that the doctor conducting this trial has since revised her conclusions (due to important differences between the treatment group and the controls), we might have wondered about the relevance of this to the average vitamin taker. The useful information we might have taken from the CARET study, that it is not wise for smokers to supplement high doses of all-cis beta-carotene, was not shared with us. The positive results for antioxidant supplements from the longest-running large trials to date, the Doctors study and the Nurses study, which were ignored by the Cochrane doctor, were also ignored by the doctors on the Inside New Zealand show.
Arguments were made which cancelled each other out, in a "cake and eat it" style. Thus, supplementing vitamins supposedly gives false security so people do not eat as well, yet positive results of studies using voluntary vitamin takers can be disregarded because studies show that such vitamin takers eat better than anyone else. Okay then...
A sensible view might be that studies using voluntary vitamin takers are far more representative of the real effect that vitamins are having on such populations than the studies used by the Cochrane Collaboration, which favoured people in medical care for various reasons being given high doses of a single vitamin, yet not being told to improve their diets or lifestyles to bring them in line with those of the average vitamin taker. Amongst the many choices made that tended to skew the results of that analysis, the decision was taken to ignore all studies in which no-one died (thus pushing otherwise "insignificant" results towards statistical significance), and to measure "death from all causes" (including accidents), meaning that no useful conclusions could be drawn about the actual health effects of the vitamins.
Because, for example, high doses of vitamin E or beta-carotene can potentially lower intake of one another, and other fat-soluble antioxidants, by competing for absorption, especially in a low-fat diet. This seems to be be a real risk, and it is eaily avoided - mostly by sensible diet. We could have been told about this risk, but that would have meant explaining a scientific principle, the kiss of death for entertainment TV. Because when it comes down to it, entertainment, not information was the point of this program.
Post Script: 2012
You might remember how the Cochrane Collaboration did a meta-analysis of antioxidant supplements some years back and found they increased mortality?
Here, some different authors re-analyse THE EXACT SAME DATA and come to the opposite conclusion.
Huh?
How come the newspapers and TV never reported - this?
Nutrients. 2010 Sep;2(9):929-49. Epub 2010 Aug 30.
Reexamination of a meta-analysis of the effect of antioxidant supplementation on mortality and health in randomized trials
Biesalski HK, Grune T, Tinz J, Zöllner I, Blumberg JB.
SourceDepartment of Biological Chemistry and Nutritional Science, University of Hohenheim, Garbenstrasse 28, D-70593 Stuttgart, Germany. biesal@uni-hohenheim.de
Abstract
A recent meta-analysis of selected randomized clinical trials (RCTs), in which population groups of differing ages and health status were supplemented with various doses of β-carotene, vitamin A, and/or vitamin E, found that these interventions increased all-cause mortality. However, this meta-analysis did not consider the rationale of the constituent RCTs for antioxidant supplementation, none of which included mortality as a primary outcome. As the rationale for these trials was to test the hypothesis of a potential benefit of antioxidant supplementation, an alternative approach to a systematic evaluation of these RCTs would be to evaluate this outcome relative to the putative risk of greater total mortality.
Thus, we examined these data based on the primary outcome of the 66 RCTs included in the meta-analysis via a decision analysis to identify whether the results provided a positive (i.e., benefit), null or negative (i.e., harm) outcome.
Our evaluation indicated that of these RCTs, 24 had a positive outcome, 39 had a null outcome, and 3 had a negative outcome. We further categorized these interventions as primary (risk reduction in healthy populations) or secondary (slowing pathogenesis or preventing recurrent events and/or cause-specific mortality) prevention or therapeutic (treatment to improve quality of life, limit complications, and/or provide rehabilitation) studies, and determined positive outcomes in 8 of 20 primary prevention studies, 10 of 34 secondary prevention studies, and 6 out of 16 therapeutic studies. Seven of the eight RCTs with a positive outcome in primary prevention included participants in a population where malnutrition is frequently described. These results suggest that analyses of potential risks from antioxidant supplementation should be placed in the context of a benefit/risk ratio.
http://www.ncbi.nlm.nih.gov/pubmed/22254063
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It confirmed what I've always known, that TV cannot report responsibly on inherently complex matters of science or history. Instead of explaining things scientifically in the detail required to give an honest version of events, time is wasted on trivia, soundtracks, action shots that add nothing to the data presented, and the data itself is so often wrong. Thus, last night we were taught that vegetables are a source of vitamin D, that vitamin B is a single vitamin, with the chemical structure of thiamine and a single list of positive and negative effects, that there is no difference between retinol and beta carotene, that vitamin deficiency syndromes in New Zealand are too rare to be worth mentioning, and so on.
Potential pro-oxidants in supplement form are excesses of iron and copper. One of the participants in the program was supplementing iron without a diagnosed deficiency, but her iron levels were not taken, because the show was about vitamins!
Thus a chance to warn the audience about the proven pro-oxidant dangers of high iron levels was missed.
Much was made of a statistical analysis of 60 antioxidant papers (chosen from the many hundreds available) called the 2008 Cochrane Collaboration, yet we were given no detail about what kind of data this actually represented. If we had been told that most of the negative statistics for vitamin E came from a single 28 day, very high-dose trial in terminal cancer patients, and that the doctor conducting this trial has since revised her conclusions (due to important differences between the treatment group and the controls), we might have wondered about the relevance of this to the average vitamin taker. The useful information we might have taken from the CARET study, that it is not wise for smokers to supplement high doses of all-cis beta-carotene, was not shared with us. The positive results for antioxidant supplements from the longest-running large trials to date, the Doctors study and the Nurses study, which were ignored by the Cochrane doctor, were also ignored by the doctors on the Inside New Zealand show.
Arguments were made which cancelled each other out, in a "cake and eat it" style. Thus, supplementing vitamins supposedly gives false security so people do not eat as well, yet positive results of studies using voluntary vitamin takers can be disregarded because studies show that such vitamin takers eat better than anyone else. Okay then...
A sensible view might be that studies using voluntary vitamin takers are far more representative of the real effect that vitamins are having on such populations than the studies used by the Cochrane Collaboration, which favoured people in medical care for various reasons being given high doses of a single vitamin, yet not being told to improve their diets or lifestyles to bring them in line with those of the average vitamin taker. Amongst the many choices made that tended to skew the results of that analysis, the decision was taken to ignore all studies in which no-one died (thus pushing otherwise "insignificant" results towards statistical significance), and to measure "death from all causes" (including accidents), meaning that no useful conclusions could be drawn about the actual health effects of the vitamins.
Because, for example, high doses of vitamin E or beta-carotene can potentially lower intake of one another, and other fat-soluble antioxidants, by competing for absorption, especially in a low-fat diet. This seems to be be a real risk, and it is eaily avoided - mostly by sensible diet. We could have been told about this risk, but that would have meant explaining a scientific principle, the kiss of death for entertainment TV. Because when it comes down to it, entertainment, not information was the point of this program.
Post Script: 2012
You might remember how the Cochrane Collaboration did a meta-analysis of antioxidant supplements some years back and found they increased mortality?
Here, some different authors re-analyse THE EXACT SAME DATA and come to the opposite conclusion.
Huh?
How come the newspapers and TV never reported - this?
Nutrients. 2010 Sep;2(9):929-49. Epub 2010 Aug 30.
Reexamination of a meta-analysis of the effect of antioxidant supplementation on mortality and health in randomized trials
Biesalski HK, Grune T, Tinz J, Zöllner I, Blumberg JB.
SourceDepartment of Biological Chemistry and Nutritional Science, University of Hohenheim, Garbenstrasse 28, D-70593 Stuttgart, Germany. biesal@uni-hohenheim.de
Abstract
A recent meta-analysis of selected randomized clinical trials (RCTs), in which population groups of differing ages and health status were supplemented with various doses of β-carotene, vitamin A, and/or vitamin E, found that these interventions increased all-cause mortality. However, this meta-analysis did not consider the rationale of the constituent RCTs for antioxidant supplementation, none of which included mortality as a primary outcome. As the rationale for these trials was to test the hypothesis of a potential benefit of antioxidant supplementation, an alternative approach to a systematic evaluation of these RCTs would be to evaluate this outcome relative to the putative risk of greater total mortality.
Thus, we examined these data based on the primary outcome of the 66 RCTs included in the meta-analysis via a decision analysis to identify whether the results provided a positive (i.e., benefit), null or negative (i.e., harm) outcome.
Our evaluation indicated that of these RCTs, 24 had a positive outcome, 39 had a null outcome, and 3 had a negative outcome. We further categorized these interventions as primary (risk reduction in healthy populations) or secondary (slowing pathogenesis or preventing recurrent events and/or cause-specific mortality) prevention or therapeutic (treatment to improve quality of life, limit complications, and/or provide rehabilitation) studies, and determined positive outcomes in 8 of 20 primary prevention studies, 10 of 34 secondary prevention studies, and 6 out of 16 therapeutic studies. Seven of the eight RCTs with a positive outcome in primary prevention included participants in a population where malnutrition is frequently described. These results suggest that analyses of potential risks from antioxidant supplementation should be placed in the context of a benefit/risk ratio.
http://www.ncbi.nlm.nih.gov/pubmed/22254063
