Re: [DIYbio] Re: Antioxidant supplements are bad for you

David Murphy <murphy.david@gmail.com> writes:

>>Really ? Do you have sources about that ?
> http://www.goodreads.com/quotes/735647-two-large-trials-of-antioxidants-were-set-up-after-peto-s
> Two groups of people at high risk of lung cancer were studied: smokers, and
> people who had been exposed to asbestos at work. Half were given 3-carotene
> and vitamin A, while the other half got placebo. Eighteen thousand
> participants were due to be recruited throughout its course, and the
> intention was that they would be followed up for an average of six years;
> but in fact the trial was terminated early, because it was considered
> unethical to continue it. Why? The people having the antioxidant tablets
> were 46 per cent more likely to die from lung cancer, and 17 per cent more
> likely to die of any cause,* than the people taking placebo pills.
>
> http://www.ncbi.nlm.nih.gov/pubmed/15572756
> The Beta-Carotene and Retinol Efficacy Trial (CARET) tested the effect of
> daily beta-carotene (30 mg) and retinyl palmitate (25,000 IU) on the
> incidence of lung cancer, other cancers, and death in 18,314 participants
> who were at high risk for lung cancer because of a history of smoking or
> asbestos exposure. CARET was stopped ahead of schedule in January 1996
> because participants who were randomly assigned to receive the active
> intervention were found to have a 28% increase in incidence of lung cancer,
> a 17% increase in incidence of death and a higher rate of cardiovascular
> disease mortality compared with participants in the placebo group.
>
>
All of that is interesting but:
They are taking tablets so:
- What are the excipients
- What is the purity of the "antioxydants". Working in a phytochemistry
lab that is concerned by this question, I can tell you that the 99.9%
purity advertised is almost NEVER the case. And when you have a 95%
purity on 30mg of something, it's still 1.5mg of … something … which we
may hope it's water… Well it's not just that… And I don't talk about
mixtures of compounds advertised as a single compound because the
analytical technique used can't discriminate between them. It's like,
hey here is a nice mattress… Oh and I have 0.01% bed bugs inside it, but
it's nothing .01% tsss…
- What about the matrix effect ? Taking a pure compound from a dry
tablet is not the same matrix as taking it from food. The pH is not the
same, the sugar/lipids content is not the same (modifying
absorption/release in the gut… hey wait a minute…). And what about the
effect of the tablet on smokers ? You have all the previous elements,
someone smokes, where are the compounds and excipients ? still in his
mouth, in his gut ?

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