lipoic acid

What high-lipoic acid foods can do for you:

  • help regenerate your vitamin C and vitamin E
  • maintain your antioxidant defense system
  • help regulate your blood sugar

What events can indicate a need for more high-lipoic foods?

  • high blood sugar
  • frequent colds or infections
  • eye problems like cataracts or glaucoma

Sources of lipoic include: dark green leafy vegetables, including spinach and collard greens; broccoli; animal foods such as beef steak; and organ meats such as calf's liver.

 

Description

What is this nutrient?

Lipoic acid (also sometimes called thioctic acid) is an enormously important and under-appreciated nutrient whose chemical structure was first discovered in 1951. Our bodies cannot be maximally efficient in producing energy from carbohydrates or fats without the help of lipoic acid. This nutrient is also classified as an antioxidant, and it plays a direct role in protecting our cells from oxygen damage. In addition, our supplies of several different antioxidants, including vitamins E and C, cannot be successfully maintained in the absence of lipoic acid.

An unusual feature of lipoic acid is its ability to function in a water-based or fat-based environment. Some nutrients, like vitamin E, tend to be associated with fat-based areas of the cell (like the cell membrane), and others, like vitamin C, are found primarily in water-based areas (like the inside of the cell, called the cytoplasm). Because lipoic acid can function equally well in both areas, it can support the activity of both types of vitamins.

Lipoic acid cannot be called a vitamin in the traditional sense of the word since our bodies appear capable of producing it. (Nutrition tradition says no substance can be designated a "vitamin" unless it is impossible to produce in the body). The way our cells produce lipoic acid is not entirely clear. We think it gets its two atoms of sulfur from an amino acid (part of protein) called methionine, and we think it gets the rest of its chemical structure from a fatty acid (part of fat) called octanoic acid.

How it Functions

What is the function of this nutrient?

Energy Production

Lipoic acid is nestled into one of the most critical spots in all of the body’s energy production pathways. It sits at the end of a process called glycolysis, which our cells use to create energy from sugars and starches. This same spot also occurs at the beginning of the pathways we use to create energy from fats. The placement of lipoic acid at this critical juncture in energy metabolism helps explain its clinical use with conditions like diabetes, where processing of sugar is disrupted, and also with skeletal muscle dysfunction in which muscle cells are unable to produce energy from fats.

Prevention of Cell Damage

The antioxidant function of lipoic acid has been extensively studied, and its ability to help prevent oxygen-based damage to cells is well established. The antioxidant role of lipoic acid may be the key factor in explaining its success in prevent cataract formation in animal studies. Prevention of oxygen-based damage to nerves is also a key area of clinical research on the possible use of lipoic acid.

Maintaining Supplies of Other Antioxidants

Because of its two-fold interactions with both water-soluble (vitamin C) and fat-soluble (vitamin E) substances, lipoic acid has been shown to prevent deficiency of both vitamins in both human and animal studies. Other antioxidants seem to benefit equally from the presence of lipoic acid. These antioxidants include coenzyme Q, glutathione, and NADH (a form of niacin).

Deficiency Symptoms

What are deficiency symptoms for this nutrient?

Because lipoic acid works so closely with many other antioxidant nutrients, deficiency symptoms for lipoic acid alone are difficult to pinpoint. Lipoic acid is required for the maintenance of vitamin C supplies, and symptoms of lipoic acid deficiency can imitate symptoms of vitamin C deficiency. These symptoms can include weakened immune function and increased susceptibility to colds and other infections. In research studies on animals, lipoic acid deficiency has been linked to problems with memory, decreased muscle mass, and failure to thrive (in young animals).

Toxicity Symptoms

What are toxicity symptoms for this nutrient?

Toxicity symptoms from excessive intake of lipoic acid have not been adequately studied. However, in clinical practice, this nutrient has been given in supplemental form for over 30 years in many European countries as a supportive nutrient for individuals with nervous system damage from diabetes, and no reports of toxicity have been reported in the literature in this regard.

In several animal studies, lipoic acid supplementation has been shown to reduce high blood sugar levels by increasing the activity of insulin and allowing sugar to leave the blood. For this reason, individuals with blood sugar imbalances, particularly hypoglycemia (low blood sugar) may experience toxic effects from excess intake of lipoic acid in the form of insufficient blood sugar. It is important to note that this phenomenon is not well-studied, and that doses of lipoic acid that might cause hypoglycemia are higher than those obtained through diet alone.

One animal study has shown potentially toxic effects of lipoic acid when given simultaneously with thyroid hormone. For this reason, individuals on prescription thyroid hormone medications may want to consult their health practitioner before supplementing with lipoic acid. Once again, the amount of lipoic acid used in this thyroid study was higher than the amount that would be obtained through diet alone.

Although not strictly falling into the category of toxic side effects, individuals with B-complex vitamin deficiencies – especially deficiency of vitamins B1 and B12 – should be sure to remedy these deficiencies when supplementing with lipoic acid. Some animal studies have shown a worsening of B-complex vitamin deficiencies when lipoic acid is supplemented in the absence of B-complex vitamins. (Note: All of the above factors involve supplements, not food, and many food sources of lipoic acid – like green leafy vegetables – are also sources of B-complex vitamins.)

Impact of Cooking, Storage and Processing

How do cooking, storage, or processing affect this nutrient?

At present, there are no studies showing the impact of cooking, storage, or processing on levels of lipoic acid in foods.

Factors that Affect Function

What factors might contribute to a deficiency of this nutrient?

Interestingly, because lipoic acid is found in the mitochondria (energy production units) of animal cells, individuals who eat no animal products may be at higher risk for lipoic acid deficiency than individuals who do. Vegetarians who eat no green leafy vegetables may also be at special risk, since the chloroplasts in these leaves house most of the lipoic acid.

Since lipoic acid protects proteins during aging, older individuals may be at greater risk of deficiency.

Similarly, because lipoic acid is used to help regulate blood sugar, individuals with diabetes may be at special risk of deficiency.

Individuals with poor protein intake, and particularly those with poor intake of the sulfur-containing amino acids (the building blocks of protein that contain sulfur, namely, methionine, cysteine, and taurine) may also be at higher risk of lipoic acid deficiency. The reason for this connection is simple: lipoic acid gets its sulfur atoms from these sulfur-containing amino acids.

Because lipoic acid is asorbed primarily through the stomach, individuals with stomach disorders (for example, hypochlorhydria, or low stomach acid) may also be at increased risk of deficiency.

Drug-Nutrient Interactions

What medications affect this nutrient?

At present, there are no studies indicating deficiency of lipoic acid as a result of medication use.

Nutrient Interactions

How do other nutrients interact with this nutrient?

Vitamins C and E, coenzyme Q, glutathione, and NADH all require lipoic acid for their efficient recycling in the body. Deficiency of these antioxidant nutrients will reduce synthesis of lipoic acid in the body.

Lipoic acid gets its two sulfur atoms primarily from the sulfur-containing amino acid methionine. For this reaspon, methionine deficiency can reduce the body’s ability to make lipoic acid. Deficiency of other sulfur-containing amino acids, like cysteine and taurine, can also prevent lipoic acid synthesis in our cells.

Health Conditions

What health conditions require special emphasis on this nutrient?

Lipoic acid may play a role in the prevention and/or treatment of the following medical conditions:
  • Cataracts
  • Chronic fatigue syndrome
  • Conditions involving chronic muscle fatigue
  • Diabetes
  • Glaucoma
  • HIV+/AIDS
  • Hypoglycemia
  • Impaired glucose tolerance
  • Insulin resistance
  • Liver diseases (including alcoholic liver disease)
  • Lung cancer
  • Neurodegenerative diseases of childhood, particularly Leigh’s disease
  • Radiation injury

Form in Dietary Supplements

What forms of this nutrient are found in dietary supplements?

In the vast majority of dietary supplements, lipoic acid is found in the form of alpha-lipoic acid. Once inside the body, this form of lipoic acid can be converted into a second form, called dihydrolipoic acid or DHLA. This second form is also available in supplemental form. Lipoic acid is usually available in doses of 25-50 milligrams, and many healthcare practitioners suggest a limit of 100 milligrams per day unless specifically advised for a specific condition such as diabetes.

Food Sources

Introduction to Nutrient Rating System Chart

The following chart shows the foods which are either excellent, very good or good sources of this nutrient. Next to each food name you will find the following information: the serving size of the food; the number of calories in one serving; DV% (percent daily value) of the nutrient contained in one serving (similar to other information presented in the website, this DV is calculated for 25-50 year old healthy woman); the nutrient density rating; and the food's World's Healthiest Foods Rating. Underneath the chart is a table that summarizes how the ratings were devised. For more detailed information on our Nutrient Rating System, please click here.

 

Food Source Analysis not Available for this Nutrient

Public Health Recommendations

What are current public health recommendations for this nutrient?

There are currently no public health recommendations for lipoic acid.

References

  • Barbiroli B, Medori R, Tritschler H-J, et al. Lipoic (thioctic) acid increases brain energy availability and skeletal muscle performance as shown by in vivo 31P-MRS in a patient with mitochondrial cytopathy. J Neurol 1995;242:472-477.
  • Groff JL, Gropper SS, Hunt SM. Advanced Nutrition and Human Metabolism. West Publishing Company, New York, 1995.
  • Jacob S, Henriksen EJ, Schiemann AL, et al. Enhancement of glucose disposal in patients with type 2 diabetes by alpha-lipoic acid. Arzneimittel-Forschaung 1995;45:872-874.
  • Kagan V, Serbinova E, Packer L. Antioxidant effects of ubiquinones in microsomes and mitochondria are mediated by tocopherol recycling. Biochem Biophys Res Comm 1990;169:851-857.
  • Maitra I, Serbinova E, Tritschler H-J, et al. Stereospecific effects of R-lipoic acid on buthionine sulfoximine-induced cataract formation in newborn rats. Biochem Biophys Res Commun 1996;221:422-429.
  • Midaoui AE, Elimadi A, Wu L et al. Lipoic acid prevents hypertension, hyperglycemia, and the increase in heart mitochondrial superoxide production. Am J Hypertens 2003 Mar;16(3):173-9.
  • Nichols TW Jr. Alpha-Lipoic acid: biological effects and clinical implications. Alter Med Rew 1997;2(3):177-183.
  • Packer L, Witt EH, Tritschler HJ, et al. Antioxidant properties and clinical implications of alpha-lipoic acid. Chapter 22 in: Packer L and Cadenas E. (Eds). Biothiols in health and disease. Marcel Dekker, New York, 1995;479-516.
  • Segermann J, Hotze A, Ulrich H, et al. Effect of alpha-lipoic acid on the peripheral conversion of thyroxine to triiodothyronine and on serum lipid-, protein- and glucose levels. Arzneimittelforschung 1991;41:1294-1298.

This page was updated on: 2003-12-11 19:48:44
© 2002 The George Mateljan Foundation