Lipoic acid is a naturally occurring antioxidant our bodies make by adding sulfur to caprylic acid, the fatty acid found in milk, especially goat's milk and coconut oil. The enzymes in the human body that synthesize lipoic acid always assemble the molecule so that it has a rightward "twist." That's why you see references to R-lipoic acid as the active form of the antioxidant.
The industrial process used to make lipoic acid in
creates both rightward (R-) and leftward (S-, for sinister) twisting forms of the chemical, collectively called alpha-lipoic acid. If you buy alpha-lipoic acid, you'll get a mixture of about 40% R-lipoic acid, which your body can use, and 60% S-lipoic acid, which your body can't use in the same ways that it uses the lipoic acid it makes on its own. Recent research, however, finds that both forms of the antioxidant have some health benefits. China
R-lipoic acid reduces insulin resistance. It makes the inner environment of the cell safer for "burning" glucose for fuel, so the cell becomes more sensitive to insulin and takes glucose out of the bloodstream. This lowers blood sugar levels, sometimes noticeably, but not enough that any diabetic is at risk of "falling out" or suffering hypoglycemia as a result of taking the supplement.
S-lipoic acid gets a bad rap from the supplement makers who sell pure R-lipoic acid (made by a different manufacturing process in
), but it also is of some benefit to diabetics. It won't lower blood sugar levels and it does not help reverse insulin resistance, but it seems to protect nerve and eye tissues from the effects of high blood sugar levels. R-lipoic acid lowers blood sugar levels, and S-lipoic acid protects against the effects of high blood sugar levels. Taking them together, as "alpha-lipoic" acid, this supplement is scientifically proven to help relieve the stinging, burning, and numbness caused by neuropathy. Italy
The SYDNEY 2 Trial tested dosages of 600, 1200, and 1800 mg of alpha-lipoic acid a day. It found that 600 mg a day was the best dosage for controlling the symptoms of diabetic neuropath. Taking 1800 mg a day greatly reduced the effectiveness of the antioxidant, and sometimes caused heartburn, nausea, and diarrhea. Regular users of alpha-lipoic acid know that taking a high dosage of the supplement, which contains sulfur, results in pungent, sulfurous urine.
If you take R-lipoic acid, which costs a lot more, you get the same benefit with a lot less. Just 300 mg a day is enough. You will get a much more immediate effect on your blood sugar levels, but a slower effect on neuropathy symptoms. If you take R-lipoic acid, it also helps to take acetyl-L-carnitine (up to 2,000 mg a day), biotin (100 mgs of biotin for every 1,000 mg of alpha-lipoic acid), and nicotinamide (up to 500 mg a day, but no more, to avoid flushing and skin breaking out). These additional supplements work with lipoic acid inside the cell to quench free radicals, make it safer for the cell to burn sugar, and reduce insulin resistance.
Bansal V, Kalita J, Misra
. Diabetic neuropathy. Postgrad Med J. 2006 Feb;82(964):95-100. UK
Ziegler D, Ametov A, Barinov A, Dyck PJ, Gurieva I, Low PA, Munzel U, Yakhno N, Raz I, Novosadova M, Maus J, Samigullin R. Oral treatment with alpha-lipoic acid improves symptomatic diabetic polyneuropathy: the SYDNEY 2 trial. Diabetes Care. 2006 Nov;29(11):2365-70.