DCI has been shown to work orally at least in PCOS, Type 2 diabetes, & general insulin resistance, both in human studies & anecdotally. Anecdotally, d-pinitol (Inzitol) is getting some attention in athletic/bodybuilder circles.
One of the central studies seems to be one in the New England Journal of Medicine (Nester, et al. Ovulatory and metabolic effects of d-chiro-inositol in the polycystic ovary syndrome. New England Journal of Medicine 340 (1999): 1314-1320). They used 1200 mg. oral doses of D-chiro-inositol in the form of a product-in-development called INS-1 from Insmed Pharmaceuticals. 22 women with PCOS were matched against a placebo group of 22 women also with PCOS. Conclusions: “D-Chiro-inositol increases the action of insulin in patients with the polycystic ovary syndrome, thereby improving ovulatory function and decreasing serum androgen concentrations, blood pressure, and plasma triglyceride concentrations.”
More research: Insmed was developing INS-2 for use in PCOS, diabetes, & dyslipidemia (high blood lipids) & ran Phase II clinical trials in 2001-2002. But they discontinued development of INS-2 in Sept. 2002, saying that “INS-1 was safe and well tolerated but did not achieve statistical significance on its primary efficacy measures” — in spite of earlier press releases about the same trials that said there were statistically significant improvements (in Type 2 diabetes; in obese women w/ PCOS & nondiabetics with dyslipidemia). Anecdotally, women on the Soulcysters PCOS board reported participating in the clinical trials & experiencing big improvements on INS-1 — for example, regular periods (which sometimes go by the slang term “AF” meaning “Aunt Flo”) & ovulation, lower hirsutism, better skin, no more hypoglycemia — improvements that disappeared after the trials ended & they were no longer getting the INS-1. People have also reported better weight loss. All of which makes me think that Insmed’s decision to discontinue was premature. It sure was from the POV of PCOS-sufferers. (I’m not trying to get preggers myself, but a lot of women with PCOS are, & inability to have periods or to ovulate creates a problem.)
Anecdotally, women at Soulcysters say that eating food sources of d-chiro-inositol such as “PCOS-blaster” muffins containing buckwheat bran brings improvements, & so do the oral DCI supplements from the company Chiral Balance. Chiral Balance is a small company run, I gather, by a couple of biochemists who seem to be approaching DCI supplementation from a nutritional supplement rather than drug/pharmaceutical angle. Unfortunately, it’s still expensive, & nutritional supplements aren’t usually covered by health insurance.
Other studies in humans with related to DCI — Iuorno et al. 2002 (DCI supplementation in PCOS); Baillargeon et al. 2004 (metformin for PCOS seems to increase DCI-containing inositolphosphoglycan). There still seems to be a lot of study of DCI’s mechanisms in insulin metabolism in mice & other animals too.
An alternative oral supplement is d-pinitol (3-O-methyl-chiroinositol) — which it seems d-chiro-inositol can easily be made from, possibly even in insulin resistant people. (I’m still trying to understand the science — I’m smart enough I guess, but not a biochemist.) Pinitol is found in high concentrations in some legumes (such as soy), plants, fruits, and parts of pine trees like the sugar pine. Two manufactured supplements containing it: Inzitol & ViTAL Nutrients d-Pinitol 600. (About $120 per 60-cap bottle on Amazon — just about as expensive as Chiral Balance’s DCI. But $79.95/bottle at this point from this source.)
Inzitol is found in a product called Meta-Cel, which also contained creatine & is aimed at bodybuilders. Also apparently in another bodybuilder supplement called Nitro-Tech that makes all kinds of (who knows if they’re valid) claims. Also apparently in some products from PVL Nutrients, but it’s not readily apparent which ones. A Google search on Inzitol brings up a lot of hits about the use of Inzitol in athletics, including bodybuilding, where it’s alleged to help with creatine utilization. E.g., this interview with someone at the New Zealand company that makes Inzitol.
In one human study on pinitol I found in PubMed, pinitol was found to increase levels of d-chiro-inositol in the body (14-fold increase in DCI levels with 20 mg pinitol per kg of body weight per day for four weeks in diabetic patients), but not to improve insulin sensitivity (Davis et al. 2000). Another found it didn’t help insulin sensitivity in nondiabetic older people (Campbell et al. 2004). On the other hand, Kim et al. 2007, in a study of poorly controlled Type 2 diabetics, found “fasting glucose, post-prandial glucose levels, and hemoglobin A1c were significantly decreased.” Similarly, Kang et al. 2006. (Both these latter two studies uses pinitol from soy sources, not sure what the other studies used. I believe Inzitol is manufactured from pine tree sources.)
From the best I understand, the proven low levels of d-chiro-inositol in Type 2 diabetics & women w/ PCOS (& other insulin resistant people) appears to be a deficiency caused by an inability to transform myo-inositol into d-chiro-inositol within the body. Whether that’s from some sort of genetic problem or due to environment (hyperglycemia &/or hyperinsulinemia, perhaps) isn’t clear. But I’m thinking it’s quite similar to how we as human beings are supposed to be able to change the omega-3 DHA found in flax seed into the essential omega-3s EPA & DHA. But, we’re pretty inefficient at it, & many people can’t seem to do it at all, so therefore we eat fish oil in order to get enough EPA/D
. Most people can make DCI in their own bodies, but insulin resistant people’s bodies are lousy at it; so we need supplementation.
So… this might not have that much utility as I thought it might for insulin sensitive dieters, who probably don’t have this deficiency… but for those of us who are insulin resistant, & eating moderate to high-carb diets, it might be very helpful indeed. Meantime, the bodybuilder supplement industry seems to be embracing Inzitol, though whether it’s anything more than something else to make money with — in an industry that sells all kinds of expensive supplements that may or may not be beneficial for the purposes advertised — is a question.
At any rate, for anyone who wants to experiment, seems that both DCI & pinitol are different from Metformin (glucophage) as insulin-sensitizers in that they are naturally found in the human body, & all reports seem to be that oral supplementation is well-tolerated & doesn’t give the nasty side effects Metformin sometimes does.
According to Joseph Larner, who’s been studying d-chiro-inositol for a couple of decades, DCI was “originally discovered as a component of a putative mediator of intracellular insulin action, where as a putative mediator, it accelerates the dephosphorylation of glycogen synthase and pyruvate dehydrogenase, rate limiting enzymes of non-oxidative and oxidative glucose disposal.” Further explained, most of it understandable even to non-biochemist-me, in the journal article of his I posted yesterday, D-chiro-inositol – its functional role in insulin action and its deficit in insulin resistance. International Journal of Experimental Diabetes Research 3(1) (2002): 47-60.