"Quartz (Silica) Goodies"

In this article [Flythe et al., 2009: (http://linkinghub.elsevier.com/retrieve/pii/S0272638608016132)], Flythe et al. (2009) discussed a case of a person who developed silica (silicon dioxide) kidney stones after the ingestion of silica as an excipient in supplements. The stones stopped forming after the person discontinued the source of silica. There are actually lots of reports of silica urolithiasis [Ichiyanagi et al., 1998: (http://www.ncbi.nlm.nih.gov/pubmed/9792982); Joekes et al., 1973: (http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1588389/pdf/brmedj01539-0034.pdf)(http://www.ncbi.nlm.nih.gov/pubmed/4350443); (http://scholar.google.com/scholar?q=related:33eEpUxra-UJ:scholar.google.com/&hl=en)]. I don't think this is likely to be a big problem for a person whose kidneys are functioning normally, but it's always possible to say things like that. "A pathological disease mechanism is likely to be more pronounced in a person in a disease state." It wouldn't be very difficult to reduce the silica intake from supplements, if one wanted to. Some supplements just use magnesium stearate as an excipient in capsules or tablets. Or one could just put the silica-containing supplements in a glass of water, let the insoluble precipitate settle (silica and calcium silicate and other silicates are not very soluble in water), and drink the water but not the silica (or pour it through a coffee machine filter--I don't know--I'm not a silica chemist, but the easier thing would just be to take some brand with no silica). From what I can tell, however, the issue is not the solubility of the silica as much as it is the fact that 1-5 percent of some forms of colloidal silica can evidently be absorbed [see last page of Jugdaohsingh et al., 2000: (http://www.ajcn.org/cgi/content/full/71/4/944)(http://www.ncbi.nlm.nih.gov/pubmed/10731501)]. That means that someone can tell a person all day that silica is insoluble, but it doesn't matter. A colloidal suspension contains, by definition, an insoluble substance that's suspended in the water or other medium (it's not called a solvent because the substance isn't being solvated). A colloid is a suspension and isn't a solution. Milk is partly a colloidal substance and is basically a lot of highly-dispersed proteins and other constituents that are not solubilized. An emulsion could be called a colloidal suspension. So if the insoluble portion can be absorbed into the bloodstream or extracellular fluid in the intestinal tract, at least, it doesn't matter, in my opinion, that it can't enter solution. It's beside the point. I looked at a few articles, and it sounds like a real mess, in the sense that one doesn't even know what "form," as in oligomeric polymers or monomers, as discussed by Jugdaohsingh et al. (2000), the silica is being supplied in.

It actually doesn't sound good to me, given that silica, in vitro, can apparently promote collagen "mineralization" (i.e. soft-tissue calcification) [see discussion by Yendt, 1973: (http://www.pubmedcentral.nih.gov/picrender.fcgi?artid=1946599&blobtype=pdf)]. Most of the reports of autoimmune diseases, in association with silica "exposure," have been in people who have inhaled silica dust (it causes a granulomatous disease, basically, in the lungs, by activating the macrophages that try to phagocytose the silica crystals and can't break them down and go wild, releasing pro-inflammatory cytokines, etc.). However, Parks et al. (2002) [Parks et al., 2002: (http://service004.hpc.ncsu.edu/toxicology/websites/courses/TOX705/papers/Parks%20et%20al%202002.pdf)(http://www.ncbi.nlm.nih.gov/pubmed/12124868)] cited research (reference 16) that had shown that silica ingestion could activate macrophages in animals (meaning that the expression and release of pro-inflammatory cytokines would be increased, etc.). It obviously can be absorbed. If it weren't absorbed, one wouldn't find cases of "pure" silica-containing kidney stones in people. Even if the issue were about solubility, the GI tract is not a system at equilibrium. If 0.5 percent or whatever of a given amount of silica is absorbed (because it's soluble) in 60 minutes, say, then 0.5 percent of the remaining amount can be absorbed over the next 60 minutes or 30 minutes or whatever. Just look at the shocking case of inulin, which is still being sold [(http://hardcorephysiologyfun.blogspot.com/2009/01/disturbing-articles-on-inulin.html); (http://hardcorephysiologyfun.blogspot.com/2009/01/note-on-inulin.html)]. Here's another one showing inulin can be absorbed through the colon in rats [Ma et al., 1995: (http://www.ncbi.nlm.nih.gov/pubmed/7806033)], not just the small intestine. I'm not sure what to say, except "that's very serious business," in my opinion. It's problematic, in my opinion, to make safety determinations that are based solely, evidently, or almost solely on the supposed insolubility of a substance or on some flimsy notions about the "inviolability" of the "brush border" of the intestinal tract. I'm joking somewhat, but oh my God. It's a nonspecific immune adjuvant (Parks et al., 2002). I used to think it was essential, too, but I'm thinking that the standard "fact" about silica essentiality (that every 100th carbon, or something similar to that, in glycosaminoglycan chains is a silicon atom and that that's evidence of essentiality) isn't evidence of essentiality. That's just my opinion, but it sounds like it might just be precipitating in the extracellular matrix. Or it might be the case that some monomeric silica is being inappropriately incorporated into some of the GAG polymers? Now that I think about it, the whole thing sounds far-fetched. I doubt silica is all that harmful, but it seems like it's one of those things, like aluminum, that may not be the sole cause of a disease (such as Alzheimer's) but just shouldn't really be in foods, in my opinion. There's research showing that aluminum can exacerbate iron-mediated lipid peroxidation, for example. The FDA should have removed aluminum from the food supply 50 years ago, but that's just one of those FDA-associated horrors.