One may - for example - have a gene that gives one an increased chance of high cholesterol levels. However, before starting on drugs and/or supplements that can lower cholesterol levels, you'd want to check whether you actually *had* high cholesterol levels, and the LDL and HDL levels; you might also want to look into, for example, whether there would be opportunities to make lifestyle changes in order to improve matters, before moving onto supplements, drugs etc. There are also questions about general health - e.g., to be blunt, if you've got something that will kill you way before cholesterol levels, there may be a good argument for not bothering to treat them. Etc... You can't know this without having a clinical history.
Ok, I see what you're getting at there. As I recall a speaker (a medical doctor as it happens) saying at one nutrition seminar I went to "if you smoke, you can leave, nothing I tell you will help much". So I mostly agree, supplementation should not be done in isolation, however I'd also argue that in many cases an ongoing assessment procedure might cost more than the price of supplementation and with similar outcomes. Still, in general you are correct, there are plenty of non-supplement interventions that should have higher priority in most peoples lives.
You'd also want to know whether any interventions lead to improved health outcomes. In terms of treatment recommendations, what's interesting isn't just whether taking supplement X lowers cholesterol levels - but whether improved health outcomes result.
Absolutel - unfortunately due to the nature of the field itself, and regulatory restrictions, this is extremely difficult to do well. What can be done more easily is "high X is linked to increased risk of Y, taking B lowers X." - and that's why you tend to get that type of claim.
Yes, classic texas sharp-shooter stuff really.
Or there were some large-scale, well-designed RCTs included in the last Cochrane review of the effects of antioxidant supplements on mortality rates
http://www.cochrane.org/reviews/en/ab007176.html
Meta-analyses are dangerous beasties at the best of times, and this paper was a classic example of why. It quite rightly came under a deal of fire, one quick
writeup here . Can one say "self-selecting sample bias"?
It also wasn't reviewing the type of supplements I consider appropriate. In most cases I do not believe synthetic analogues can replace the effects of nutrients in food. This is one reason why epidemiological studies on fruit and vegetable consumption so often seem to show positive benefits whereas "vitamin" studies do not. The nutritional composition (and benefits) of food is far more complex than simple isolated vitamins. Many require different cofactors to work efficiently. Many of the commercialised synthetic forms don't even accurately chemically represent the natural forms. Take "Vitamin E" - 8 forms in nature, but you only need to synthesise one and stick it in a tablet to call it Vitamin E, and now there's research starting to indicate that the tocotrienol forms, once considered unusable by humans, may have significant health benefits, perhaps outstripping the classic "vitamin E".
The Nutrilite approach, which I like, is to identify plants high in particular nutrients, then selectively breed and cultivate to increase concentrations, then create a powder concentrate of the plants and put into tablet or capsule form, boosted with synthetic varients where the science supports it (ascorbic acid for example). The idea is you're getting nutrients in similar form to food, with all the accompanying cofactors. Now obviously processing always has risks of destroying some important compound we're not currently aware of, but as the knowledge improves so does the processing.
Have any supplements been withdrawn when research showed them to be ineffective for what they are sold for..?
Not withdrawn that I know of, but Nutrilite regularly reformulates their products as knowledge improves. I can't recall specific examples, but that has included removal of ingredients, yes.
I appreciate that plasma homocysteine levels correlate with certain health outcomes. It seems pretty clear that certain supplement regimes lower plasma homocysteine levels (though you wouldn't need to buy Amway's 'premium' pills to do that - cheap, generic pills can also achieve this). As far as I'm aware, though, it doesn't look like these interventions lead to significantly improved health outcomes.
Pill=lower plasma homocysteine, therefore take pill is a "magic bullet" type approach I don't prescribe to. Amway's "premium pills" aren't targeted to that approach. They actually incorporate 23 different plant concentrates as well as various other vitamins and minerals. Nutrilite does do studies comparing with the generic brands as well, and it does do a better job, as you would expect if you believe that it's better to get nutrients from food than from a chemistry lab.
Found
this monograph you might find interesting, only versus placebo though.
. Alas, no, the study isn't published for the types of reasons I gave above.
