Hi Steve and all,
Yes there’s no doubt that there are substances that increase and those that decrease during aging in mammals (at least). Both lists of chemicals are however incomplete as we don’t know all of the substances in the blood and have no way of knowing whether they increased or decreased. So for example – membrane-bound ‘exosomes’ – packages of miRNA (important in controlling the extent of translation of messengers) are released into the blood and and taken up by other cells. Those other cells have their behaviors (in terms of translation) changed by the exosomes taken up. So two years ago you might never have heard of miRNA containing exosomes. Do they increase or decrease during aging? That is not even an ask-able question as the contents of those exosomes undoubtedly change during aging – as the miRNA populations are known to change during aging (and in other circumstances as well – like cancer). Are there other things apart from miRNA-containing exosomes that we don’t know about? Who knows (and anyone that assumes they do is making an assumption that many others have made throughout the years and have been shown wrong based on later discoveries of new blood-borne factors). So I wouldn’t presume…. On the other hand there is a way to change old blood so that it exactly mirrors young blood – and preliminary experiments shows that it works to produce rejuvenation. If anyone is interested – and I think this is the real beginning of our ability to control aging – please read my paper, “Studies that shed a new light on aging” at http://ift.tt/1EfWK85 or if that’s no good just do what I did and Google, “Harold Katcher studies that shed a new light on aging” – it comes right up.