Alpha Lipoic Acid

Technical Background

Alpha lipoic acid, also known as thioctic acid, is a vitamin-like antioxidant¹ that is easily absorbed through the gut and transported across cell membranes, offering protection against a wide variety of free radicals both inside and outside the cell.²
Once in the bodys tissues, alpha lipoic acid can be converted to dihydrolipoic acid (DHLA), an equally potent free radical scavenger.
Alpha lipoic acid and DHLA provide additional benefits beyond their direct antioxidant activities. Both act to regenerate, and thus prolong the activity of, other antioxidant molecules including Vitamin C, glutathione, CoQ10, and, indirectly, Vitamin E.³ Both can act as metal chelators, binding up excess copper, iron, mercury and cadmium, thus limiting the negative impacts of these heavy metals on the body.^4,5 Finally, there is evidence that alpha lipoic acid and DHLA have effects on regulatory proteins and on genes involved in normal cell growth and metabolism.⁶
Several experimental and clinical studies have shown that, given the above attributes, alpha lipoic acid has potential therapeutic uses in preventing and/or treating such conditions as diabetes, atherosclerosis, cataracts, heavy metal poisoning, neurodegenerative diseases, and HIV infection.⁷

Sources and Recommended Intake

Alpha lipoic acid is produced naturally by most organisms including humans. It is present in most foods that we eat. Potatoes provide a particularly significant dietary source.
No Recommended Daily Intake has been set. Nor has the issue been adequately studied. Some researchers believe that the amount needed for therapeutic antioxidant activity exceeds that produced by our bodies and consumed in a normal diet. As such, alpha lipoic acid is a strong candidate for supplementation. Maintenance doses of 10-25 mg per day are suggested. Therapeutic doses of up to several hundred milligrams per day have been used.

Abstracts

Filina AA, Davydova NG, Endrikhovskii SN, Shamshinova AM. Lipoic acid as a means of metabolic therapy of open-angle glaucoma. Vestn Oftalmol 1995 Oct-Dec;111(4):6-8. A total of 45 patients (90 eyes) with stages I and II open-angle glaucoma (OAG) were examined, 26 of these were administered lipoic acid in a daily dose of 0.075 g for 2 months and 19 were given 0.15 g daily for 1 month. Control group consisted of 31 patients with OAG who were administered only local hypotensive therapy. Vision acuity and visual field were checked up, tonometry, tonography, and campimetry carried out, and levels of nonprotein SH-groups and activity of gamma-glutamyl transpeptidase measured in the lacrimal fluid. Improvement of the biochemical parameters, visual function, and of the coefficient of efficacy of liquid discharge was more expressed in the patients administered lipoic acid in a daily dose of 0.15 g. Color campimetry results indicate improved sensitivity of the visual analyzer under the effect of treatment. Improvement was attained in approximately 45-47.5% of examined eyes, and was more often seen in patients with stage II OAG: in 57-58% eyes. The effect of lipoic acid may be explained by its antioxidant properties and direct influence on ocular tissue metabolism.

Ziegler D, Hanefeld M, Ruhnau KJ, Meissner HP, Lobisch M, Schutte K, Gries FA. Treatment of symptomatic diabetic peripheral neuropathy with the anti-oxidant alpha-lipoic acid. A 3-week multicentre randomized controlled trial (ALADIN Study). Diabetologia 1995 Dec;38(12):1425-33. Anti-oxidant treatment has been shown to prevent nerve dysfunction in experimental diabetes mellitus, thus providing a rationale of potential therapeutic value for diabetic patients. The effects of the anti-oxidant alpha-lipoic acid (thioctic acid) were studied in a 3-week multicentre, randomized, double-blind placebo-controlled trial (Alpha-Lipoic Acid in Diabetic Neuropathy; ALADIN) in 328 non-insulin-dependent diabetic patients with symptomatic peripheral neuropathy who were randomly assigned to treatment with intravenous infusion of alpha-lipoic acid using three doses (1200, 600, or 100 mg ALA) or placebo (PLAC). Neuropathic symptoms (pain, burning, paraesthesiae, and numbness) were scored at baseline and at each visit (days 2-5, 8-12, and 15-19) prior to infusion. In addition, the Hamburg Pain Adjective List, a multidimensional specific pain questionnaire, and the Neuropathy Symptom and Disability Scores were assessed at baseline and day 19. According to the protocol 260 (65/63/66/66) patients completed the study. The total symptom score in the feet decreased from baseline to day 19 by -4.5 +/- 3.7 (-58.6%) points (mean +/- SD) in ALA 1200, -5.0 +/- 4.1 (-63.5%) points in ALA 600, -3.3 +/- 2.8 (-43.2%) points in ALA 100, and -2.6 +/- 3.2 (-38.4%) points in PLAC (ALA 1200 vs PLAC: p = 0.003; ALA 600 vs PLAC: p < 0.001). The response rates after 19 days, defined as an improvement in the total symptom score of at least 30%, were 70.8% in ALA 1200, 82.5% in ALA 600, 65.2% in ALA 100, and 57.6% in PLAC (ALA 600 vs PLAC; p = 0.002). The total scale of the Pain Adjective List was significantly reduced in ALA 1200 and ALA 600 as compared with PLAC after 19 days (both p 0.01). The rates of adverse events were 32.6% in ALA 1200, 18.2% in ALA 600, 13.6% in ALA 100, and 20.7% in PLAC. These findings substantiate that intravenous treatment with alpha-lipoic acid using a dose of 600 mg/day over 3 weeks is superior to placebo in reducing symptoms of diabetic peripheral neuropathy, without causing significant adverse reactions.

References

¹ Suzuki, Y.J., M. Tsuchiya, and L. Packer. 1991. Thioctic acid and dihydrolipoic acid are novel antioxidants which interact with reactive oxygen species. Free Rad. Res. Commun., 15: 255-263
² Packer, L., E.H. Witt, and H.J. Tritschler. 1996. Antioxidant properties and clinical applications of alpha-lipoic acid and dihydrolipoic acid. Pp. 545-591. In. E. Cadenas and L. Packer (eds). Handbook of Antioxidants. Marcel Dekker, Inc., New York.
³ Podda, M., H.J. Tritschler, H. Hlrich, and L. Packer. 1994. a -lipoic acid supplementation prevents symptoms of vitamin E deficiency. Biochem. Biophys. Res. Commun., 204: 98-104.
⁴ Sigel, H. and B. Prijs. 1978. Stability of binary and ternary complexes of a -lipoate and lipoate derivatives with Mn 2+, Cu2+, and Zn2+ in solution. Arch. Biochem Biophys. 187: 208-214.
⁵ Ou, P., H.J. Tritschler, and S.P. Wolff. 1995. Thioctic (lipoic) acid: a therapeutic metal-chelating antioxidant? Biochem. Pharmacol., 50: 123-126.
⁶ Packer, L., E.H. Witt, and H.J. Tritschler. 1996. Antioxidant properties and clinical applications of alpha-lipoic acid and dihydrolipoic acid. In. E. Cadenas and L. Packer (eds). Handbook of Antioxidants. Marcel Dekker, Inc., New York. p 562-4.
⁷ Packer, L., E.H. Witt, and H.J. Tritschler. 1996. Antioxidant properties and clinical applications of alpha-lipoic acid and dihydrolipoic acid. In. E. Cadenas and L. Packer (eds). Handbook of Antioxidants. Marcel Dekker, Inc., New York. p 566-81.