Alpha-lipoic acid with the chemical molecular formula C8H14O2S2 is a sulfur-containing fatty acid which, as a coenzyme, is a component of the pyruvate dehydrogenase complex in the mitochondria of almost all living organisms with cell nuclei (eukaryotes). Alpha-lipoic acid is bioactive only in the R-form, but not as an enantiomer in the S-form, which differs from the R-form only by a different stereostructure (tertiary structure). In the reduced form of R-lipoic acid, dihydrolipoic acid, which is also bioactive, the two ring-shaped sulfur bonds are broken and each is occupied by a hydrogen atom.
What are the functions of alpha lipoic acid in the body?
In every living cell of the body there are about 1,000 to over 100,000 mitochondria, organelles with their own genetic material, which are mainly responsible for energy metabolism and are therefore also called power plants of the cells. The catalytic biochemical conversions take place mainly in the matrix of the mitochondria. The most important conversion complexes are the pyruvate dehydrogenase complex and the alpha-ketoglutarate dehydrogenase complex (part of the citrate cycle). In many of the catalytic reactions, alpha-lipoic acid is involved mainly as a hydrogen and acyl group transporter.
Together with the form reduced to dihydrolipoic acid, alpha-lipoic acid forms an extremely effective redox system that acts as a radical scavenger and the most powerful antioxidant known. The system can even regenerate “spent” antioxidants such as vitamins C and E, coenzyme Q10 and glutathione. Dihydrolipoic acid has the property of chelating metals such as mercury, cadmium, iron and copper to “capture” and render them harmless. As a special feature, the fatty acid can cross the blood-brain barrier and occupy extracellular spaces. Alpha lipoic acid is therefore an effective antioxidant for the brain and peripheral and central nervous system.
How is the body supplied with alpha lipoic acid?
Alpha lipoic acid plays an indispensable and central role in many metabolic processes. Therefore, a sufficient supply of the fatty acid is enormously important for maintaining health and for supportive therapy in many diseases. It is assumed that the body can synthesize alpha lipoic acid itself in small quantities. The metabolism for the synthesis is not sufficiently clarified. Some scientists argue that alpha-lipoic acid – similar to vitamin K – is synthesized by bacteria in the human intestine.
The sulfur-containing fatty acid is found in small quantities in foods. Vegetables such as tomatoes, spinach, broccoli and others contain alpha-lipoic acid in the detectable range. Higher concentrations of about 4 – 10 mg /100 g are found in red meat and especially in offal such as heart and liver.
The amount of alpha-lipoic acid absorbed through food can only be estimated imprecisely, so that a controlled intake through dietary supplements in the form of capsules and tablets is recommended. Alpha-lipoic acid is also available as a drug for the treatment of certain diseases.
Applications and dosage of L-tyrosine
Dosage recommendations range from about 300 mg to well over 2,000 mg daily, depending on the area of application. Side effects in the event of a possible overdose are not known, except for nausea in very rare cases, but these are also observed after taking placebos. The safe upper limit is considered to be about 4,500 mg daily for a person weighing 80 kg.
The main areas of application are:
– Protection of the liver by detoxification (also in fungal poisoning) and reduction of oxidative stress.
– Diabetes mellitus, type 1 and 2: improvement of metabolic syndrome, diabetic polyneuropathy, diabetic nephropathy, diabetic retinopathy (cataract)
– Protection of peripheral and central nervous system from oxidative damage and from degenerative changes (Parkinson’s disease)
– protection of heart and blood vessels by stimulating the synthesis of the messenger substance nitric oxide (NO)
– Support in many types of cancer by suppressing inflammatory cytokines and by promoting apoptosis of cancer cells
– Anti-aging agent: The strong antioxidant effect leads to slowed cell aging
The antioxidant effect of alpha lipoic acid together with dihydrolipoic acid can be further enhanced by combining it with vitamin E.
