Alpha-lipoic acid is an antioxidant, which is a powerful substance that may help slow the aging process and fight disease. More commonly known antioxidants are vitamins A, C, and E. Antioxidants work by attacking "free radicals," waste products created when our bodies turn food into energy. Free radicals cause harmful chemical reactions that can damage cells, making it harder to fight off infections and lowering defenses against cancer and heart disease. In fact, free radical damage may be the basis for the aging process.

Antioxidants work by attaching to free radicals and neutralizing them. Free radicals are useful in small amounts, but when there are too many of them in our bodies, they can cause problems. Today there are more and more sources of free radicals in our environment—for example, ultraviolet rays, radiation, and toxic chemicals in cigarette smoke, car exhaust, and pesticides.

Alpha-lipoic acid (also called thioctic acid) works together with other antioxidants such as vitamins C and E. It is important for growth, helps the body produce energy, and aids the liver in removing harmful substances from the body. Alpha-lipoic acid (ALA) also prevents cell damage, controls blood sugar, and removes toxic metals from the blood. In animal studies, alpha-lipoic acid improved brain function as well. Because it is both water- and fat-soluble, ALA can function in almost any part of the body, including the brain.

Alpha-lipoic acid has been used to treat chronic hepatitis because it relieves stress on the liver and helps it rid the body of toxins. It is the standard treatment for Amanita poisoning (Amanita is a highly poisonous mushroom). Alpha-lipoic acid can help lessen the toxic effects of drugs used during surgery and for pain control afterwards. A recommended dose for this purpose is two 100-mg capsules three times daily, with meals, one week before surgery and for two weeks after the operation.

Unlike other substances, alpha-lipoic acid can pass easily into the brain, and studies have shown that ALA has protective effects on brain and nerve tissue. ALA is promising as a treatment for stroke and other brain disorders involving free-radical damage. Animals treated with alpha-lipoic acid had a four times greater survival rate after a stroke.

In more than one study, treatment with ALA helped reduce pain, burning, itching, tingling, and numbness in people who had nerve damage caused by diabetes. Other studies have shown that alpha-lipoic acid speeds the removal of glucose (sugar) from the blood of people with diabetes, and leads to improved heart function.

Good food sources of alpha-lipoic acid include spinach, broccoli, beef, yeast, kidney, and heart.

Alpha-lipoic acid is available in capsule form.

Alpha-lipoic acid is made by the body and is available in foods. It can be purchased in various dosages—from 30-mg to 100-mg tablets. Currently there are no established recommended doses. ALA manufacturers suggest one or two 50-mg capsules daily as a dietary supplement.

People with diabetes should consult with their health care provider before taking alpha-lipoic acid because it has been associated with hypoglycemia (low blood sugar). If you are pregnant or nursing, consult your health care provider before taking any supplement.

In an animal study, alpha-lipoic acid supplements reduced side effects, particularly toxicity to the ear, associated with the antibiotics, amikacin and gentamicin. Additional studies are needed to confirm these effects in humans. Similarly, the use of alpha-lipoic acid supplements in animals protected against toxic side effects associated with the use of both cisplatin and cyclophosphamide. Consult with your healthcare provider before taking alpha-lipoic acid supplements if you are taking any of these medications.

Rats given alpha-lipoic acid supplements had altered thyroid hormone function, but improved cholesterol levels. You would be wise to refrain from using alpha-lipoic acid supplements except under the supervision of a healthcare provider. Blood hormone levels and thyroid function tests should be monitored closely in patients taking thyroid hormones, such as levothyroxine, with alpha-lipoic acid.

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