Lipoic acid as a dietary supplement
Lipoic acid, also known as α-lipoic acid, is a natural compound found in every cell of the body, playing a crucial role in energy production and acting as a potent antioxidant. It is unique among antioxidants due to its ability to work in both water and fat environments, which allows it to protect various cellular components from damage caused by free radicals. While the body typically produces sufficient lipoic acid, certain health conditions, such as diabetes, may lead to lower levels, prompting interest in dietary supplementation.
Lipoic acid is primarily proposed for the treatment of diabetic neuropathy, a condition that affects the nerves, particularly in the arms and legs. It has shown some promise in improving symptoms of diabetic autonomic neuropathy, affecting heart function as well. Beyond these uses, lipoic acid may also offer potential benefits for conditions like burning mouth syndrome, hypertension, and possibly weight loss, although evidence varies in strength and consistency.
Typical dosages for therapeutic use range from 300 to 1,800 mg daily, with safety generally observed up to 1,800 mg. However, it is important to consider that lipoic acid can interact with certain medications and may not be suitable for everyone, especially those with specific health issues. As with any supplement, individuals should consult healthcare professionals before starting lipoic acid to ensure it aligns with their health needs.
Lipoic acid as a dietary supplement
DEFINITION: Essential natural substance used as a dietary supplement for specific health benefits.
PRINCIPAL PROPOSED USE: Diabetic neuropathy (peripheral neuropathy and cardiac autonomic neuropathy)
OTHER PROPOSED USES: Burning mouth syndrome, cancer prevention, cataract prevention, diabetes (blood sugar control), glaucoma, heart disease prevention, liver disease, migraine headaches, sun-damaged skin, blood pressure, weight loss
Overview
Lipoic acid, also known as α-lipoic acid, thioctic acid, and alpha-lipoic acid, is a sulfur-containing fatty acid. It is found inside every cell of the body, where it helps generate the energy that keeps humans alive and functioning. Lipoic acid is a key part of the metabolic machinery that turns glucose (blood sugar) into energy for the body’s needs.
Lipoic acid is an antioxidant, which means that it neutralizes naturally occurring but harmful chemicals known as free radicals. Unlike other antioxidants, which work only in water or fatty tissues, lipoic acid is unusual in that it functions in both water and fat. By comparison, vitamin E works only in fat, and vitamin C works only in water. This gives lipoic acid an unusually broad spectrum of antioxidant action.
Lipoic acid also may help regenerate other antioxidants that have been used up. In addition, lipoic acid can do the work of other antioxidants when the body is deficient in them.
It is thought that certain nerve diseases are at least partially caused by damaging free radicals. Because of its combined fat and water solubility, lipoic acid can get into all the parts of a nerve cell and potentially protect it against such damage. This is the rationale for studies on the potential benefits of lipoic acid for diabetic neuropathy.
Sources
A healthy body makes enough lipoic acid to supply its requirements; external sources are not necessary. External sources of lipoic acid include broccoli, potatoes, red meat, spinach, beets, and peas.
However, several medical conditions appear to be accompanied by low levels of lipoic acid (specifically diabetes, liver cirrhosis, and atherosclerosis), which suggests (but does not prove) that supplementation would be helpful. Liver and yeast contain some lipoic acid, but supplements are necessary to obtain therapeutic dosages.
Therapeutic Dosages
The typical dosage of oral lipoic acid for treating complications of diabetes ranges significantly between studies from 100 to 1,800 milligrams (mg) three times daily. Most research indicated that 300 to 600 mg daily is safe for up to six months. In studies that found benefits, several weeks of treatment were often necessary for full effects to develop.
For use as a general antioxidant, a lower dosage of 20 to 50 mg daily is commonly recommended, although there is little scientific evidence that taking lipoic acid in this way offers any health benefit. For weight loss, 300 to 1,800 mg is most often used.
Therapeutic Uses
Lipoic acid has been used for decades in Germany to treat diabetic peripheral neuropathy. This is a condition caused by diabetes in which nerves leading to the arms and legs become damaged, resulting in numbness, pain, and other symptoms. Free radicals are hypothesized to play a role in neuropathy, and on this basis, lipoic acid has been tried as a treatment. However, the evidence for benefit is largely limited to studies that used the intravenous form of this supplement.
Another set of nerves also may become damaged in diabetes: the autonomic nerves that control internal organs. When this occurs in the heart (cardiac autonomic neuropathy), it leads to irregularities in heart rhythm. There is some evidence that lipoic acid supplements may be helpful for this condition.
Preliminary and sometimes contradictory evidence suggests that lipoic acid may improve other aspects of diabetes, including blood sugar control and the development of long-term complications, such as diseases of the heart, kidneys, and small blood vessels. There is also mixed evidence concerning lipoic acid's use in weight loss, but some research supports its use in reaching and maintaining a healthy body mass index.
Mixed evidence exists for lipoic acid's benefits in treating burning mouth syndrome, a condition characterized by unexplained scalding sensations in the mouth. Weak evidence hints that the use of lipoic acid might help prevent migraine headaches. A cream containing 5 percent lipoic acid has shown promise for treating sun-damaged skin.
One animal study suggests that lipoic acid might help prevent age-related hearing loss. Similarly, weak evidence hints that lipoic acid might be helpful for glaucoma and for reducing the side effects (specifically, cardiac toxicity) of the cancer chemotherapy drug doxorubicin. Other uses for which lipoic acid has been proposed include preventing cancer and heart disease and treating or preventing cataracts.
Scientific Evidence
Diabetic peripheral neuropathy. There is some evidence that intravenous lipoic acid can reduce symptoms of diabetic peripheral neuropathy, at least in the short term. However, the evidence for oral lipoic acid remains weak and contradictory. For example, a double-blind, placebo-controlled study of five hundred people with diabetic neuropathy found that intravenous lipoic acid helped reduce symptoms over three weeks. Long-term oral supplementation did not prove effective. Benefits were seen with oral lipoic acid in a study published in 2006. In this double-blind, placebo-controlled trial, 181 people with diabetic peripheral neuropathy were given either a placebo or one of three doses of lipoic acid: 600, 1,200, or 1,800 mg daily. Over the five-week study period, benefits were seen in all three lipoic acid groups compared with the placebo group.
While this outcome may sound promising, one feature of the results tends to reduce the faith one can put in them: the absence of a dose-related effect. Ordinarily, when a treatment is effective, higher doses produce relatively better results. When such a spectrum of outcomes is not observed, the study becomes questionable. Other than this one study, the positive evidence for oral lipoic acid in diabetic peripheral neuropathy is limited to open studies of minimal to no validity and double-blind trials too small to be relied upon. There is some preliminary evidence that lipoic acid could be more effective if it were combined with gamma-linolenic acid, another supplement used for diabetic peripheral neuropathy.
Diabetic autonomic neuropathy. There is better evidence for oral lipoic acid in the form of diabetic neuropathy affecting the nerves that supply the heart: autonomic neuropathy. Not only does diabetes damage the nerves in the arms and legs, but it can also affect deep nerves that control organs, such as the heart and digestive tract.
The Deutsche Kardiale Autonome Neuropathie study followed seventy-three people with diabetes who had symptoms caused by nerve damage affecting the heart. Treatment with 800 mg daily of oral lipoic acid showed statistically significant improvement compared with the placebo and caused no significant side effects.
Burning mouth syndrome. Persons with burning mouth syndrome (BMS) feel chronic scalding pain in the mouth as if they had consumed an excessively hot drink. Although the cause of BMS is unknown, the symptoms resemble those of neuropathy, so researchers have investigated the potential benefits of lipoic acid. In a two-month, double-blind trial involving sixty people with BMS, lipoic acid significantly reduced symptoms compared with the placebo. However, three small double-blind trials failed to find any benefit for lipoic acid.
Blood pressure. An acid dose-response meta-analysis investigating the impact of lipoic acid on systolic (SBP) and diastolic blood pressure (DBP) found positive impacts of using the supplement. In eleven randomized controlled trials of over 650 people with chronic hypertension, SBP, and DBP both decreased when using a lipoic acid supplement for at least twelve weeks. Positive results were seen in doses over 800 milligrams per day. While this research requires standardization to determine confirmatory results, this finding lays a foundation for the potential of lipoic acid’s use in hypertensive patients.
Safety Issues
Lipoic acid appears to have no significant side effects at dosages up to 1,800 mg daily. Safety for young children, pregnant or nursing women, and those with severe liver or kidney disease has not been established.
Lipoic acid supplements may decrease the effectiveness of several cancer treatments, such as antitumor antibiotics, alkylating agents, and chemotherapy. Lipoic acid also reduces thyroid hormone. These supplements may also increase the blood clotting effect of anticoagulants, increasing the risk of bleeding or lowering blood sugar levels in individuals taking antidiabetes drugs.
Bibliography
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