In recent years, increasing attention has been paid to the group of vitamins,
minerals, and enzymes known as antioxidants. Some of the better known
antioxidants are vitamins A, C and E, beta-carotene, selenium, and melatonin.
Antioxidants play an important role in preventing aging-related degenerative
conditions through their actions in fighting free radicals. Free radicals are
wastes generated by the regular metabolic processes in the cells. Free radicals
are normally present in the body and actually serve useful purposes, such as
aiding in the production of hormones and activating enzymes. However, when there
is an excess of free radicals in the body, they become destructive.
In addition to being by-products of normal metabolic processes, free radicals
also can result from exposure to radiation, toxic chemicals (such as those
contained in cigarette smoke, automobile exhaust, and other environmental
pollutants), and from overexposure to the sun's rays. Free radicals are atoms or
molecules that contain unpaired electrons. They tend to bind to other molecules,
causing chemical reactions that can be destructive to the body. They can damage
cells, interfere with the immune system, and contribute to degenerative diseases
such as cancer and cardiovascular disease. In fact, free radical damage may be
the basis for the aging process. Antioxidants bind with these reactive molecules
to counteract their harmful effect.
The antioxidant alpha-lipoic acid (also called thioctic acid) is made by the
body and directly supports detoxifying abilities of the liver. It enhances the
antioxidant functions of vitamins C and E and glutathione. Alpha-lipoic acid has
growth-stimulating properties, prevents cell damage, regulates blood sugar, and
chelates toxic metals out of the blood. In animal studies, it has been shown to
enhance cognitive function as well. It is also involved in the production of
muscular energy and directs calories toward energy production. Because it is
both water- and fat-soluble, alpha-lipoic acid is able to function in almost any
part of the body, including the brain.
Dietary sources of alpha-lipoic acid include the following:
Alpha-lipoic acid, along with glutathione, is one of the thiol antioxidants.
It is a carboxy acid with two sulfur atoms in its molecule, and occurs as an
amide in plant and animal tissues.
Alpha-lipoic acid is available commercially in capsule
Because alpha-lipoic acid relieves stress on the liver and directly supports
its detoxifying functions, it has been used in the treatment of chronic
hepatitis and Amanita (a particularly toxic mushroom) poisoning. It is able to
bind to toxic metals and is used for heavy metal detoxification. Alpha-lipoic
acid can help eliminate toxic effects of anesthesia, analgesics, or other drugs
used in the course of surgery, and to ease subsequent pain. A recommended dose
is two 100-mg capsules tid one week before surgery and two weeks
The thiols are central to antioxidant defense in the brain. Alpha-lipoic acid
has a low molecular weight; it is readily absorbed from nutritional sources and
crosses the blood-brain barrier. Current research indicates that alpha-lipoic
acid and its metabolite dihydrolipoate have protective effects on brain and
neural tissue. Preliminary human studies support conclusions of animal and in
vitro studies showing a role for alpha-lipoic acid in the treatment of stroke
and other brain disorders involving free radical damage. In an animal study,
treatment with alpha-lipoic acid was associated with a four-fold increase in
Alpha-lipoic acid has shown great promise in the treatment of nerve
dysfunction in diabetics. Diabetes mellitus is associated with free radicals;
studies with diabetics have revealed oxidative stress loads. In more than one
study, treatment with alpha-lipoic acid has significantly reduced the pain,
burning, paresthesia, and numbness associated with diabetic neuropathy.
Alpha-lipoic acid has also been shown to increase glucose transport in
diabetics, and to lead to improved heart rate variability.
|Dosage Ranges and Duration of
Currently, no recommended dosages have been established for alpha-lipoic
acid. Alpha-lipoic acid manufacturers suggest one or two 50-mg capsules daily as
a dietary supplement.
Studies investigating the effects of alpha-lipoic acid on nerve damage
related to diabetes found no side effects at the dosage levels they were
Diabetics should take ALA with caution as it can cause
Supplementation with alpha-lipoic acid (100 mg/kg/day) in rats treated with
amikacin significantly reduced cochlear damage caused by ototoxic doses of this
drug (Conlon et al. 1999). Treatment with alpha-lipoic acid (25 mg/kg/day) also
ameliorated the oxidative stress caused by gentamicin (100 mg/kg/day) in rats
(Sandhya and Varalakshmi 1997). Gentamicin-induced oxidative stress is thought
to underlie the potentially serious renal side effects associated with this
A study comparing alpha-lipoic acid at several different doses (25 to 100
mg/kg), with and without cisplatin, concluded that the alpha-lipoic acid
conferred significant protection against cisplatin ototoxicity at all dose
levels in rats (Rybak et al. 1999). This effect was associated with improvements
in glutathione metabolic markers and reduced oxidative stress.
Preclinical evidence suggests that alpha-lipoic acid may protect against the
cytotoxic effects induced by cyclophosphamide (Faust et al. 1994).
Supplementation with alpha-lipoic acid significantly reduced the incidence of
cyclophosphamide-induced diabetes in mice.
In rats, alpha-lipoic acid (7.5 mg/100 g/day) inhibited enzymatic conversion
of triiodothyronine (T3) to thyroxine (T4) (Segermann et
al. 1991). Alpha-lipoic acid supplementation with T4 also had an
apparent synergistic effect on serum cholesterol, producing significantly
greater depression than T4 alone. Blood hormone levels and thyroid
function tests should be monitored for this potential
Conlon BJ, Aran JM, Erre JP, et al. Attenuation of aminoglycoside-induced
cochlear damage with the metabolic antioxidant alpha-lipoic acid. Hear
Faust A, Burkart V, Ulrich H, et al. Effect of lipoic acid on
cyclophosphamide-induced diabetes and insulitis in non-obese diabetic mice.
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antioxidant alpha-lipoic acids. Free Radic Biol Med. 1997;22:359-378.
Rybak LP, Husain K, Whitworth C, et al. Dose dependent protection by lipoic
acid against cisplatin-induced ototoxicity in rats: antioxidant defense system.
Toxicol Sci. 1999;47:195-202.
Sandhya P, Varalakshmi P. Effect of lipoic acid administration on
gentamicin-induced lipid peroxidation in rats. J Appl Toxicol.
Segermann J, Hotze A, Ulrich H, et al. Effect of alpha-lipoic acid on the
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Copyright © 2000 Integrative Medicine
CommunicationsThis publication contains
information relating to general principles
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