α-Lipoic acid (ALA)

Story

Connected to · 4

cofactor · 4

Niacin
On the two large enzyme complexes that feed fuels such as pyruvate into the citric acid cycle, lipoic acid acts like a swinging arm, passing the electrons stripped off the fuel through a riboflavin-based coenzyme to NAD⁺. NAD⁺ is made from niacin (vitamin B3) and is the last to take the baton in this relay.
Thiamin
Three enzyme complexes, pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and branched-chain keto acid dehydrogenase, all need both thiamin (B1) and lipoic acid: B1 cuts a carbon-carbon bond in the fuel molecule, and lipoic acid passes the removed piece on to the next step. Without either one, these steps stall.
Riboflavin
The last subunit of these enzyme complexes takes the electrons from the lipoic acid arm and passes them first to FAD, then to NAD⁺. FAD is made from riboflavin (B2), so riboflavin runs the leg right after lipoic acid.
Pantothenic Acid
Pyruvate dehydrogenase uses both lipoic acid and coenzyme A: the two-carbon piece cut from pyruvate is handed by the lipoic acid arm to coenzyme A, forming acetyl-CoA, which can then enter the citric acid cycle. Coenzyme A is made from pantothenic acid (B5). The enzyme needs five helper molecules in all and stalls without any one of them.

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Soluble in both water and fat

EVIDENCEREVIEW 2

READ THE ORIGINAL

α-Lipoic acid () is a small molecule your body makes for itself. It is not a vitamin, and you cannot run short of it. Its real job in the body is to serve as a part on several mitochondrial enzymes that burn sugar for energy; the antioxidant effect sold on supplement labels is only a side job.

What makes it unusual is that it dissolves in both water and fat. Most antioxidants can work only in the watery part of a cell or only in the fatty part; ALA can get into both.

Your cells make it all the time, so there is no such thing as falling ill from a lack of it. Food holds only micrograms of it, while one supplement capsule holds several hundred milligrams, an amount no diet could supply. Calling it an essential nutrient is supplement marketing. The identity that does hold up is a different one: in Germany, China and some other countries it is a prescription drug for diabetic peripheral neuropathy (nerve damage in the feet and hands from high blood sugar, felt as numbness and prickling), and the evidence that it eases those symptoms comes from randomized trials. The chapter on easing diabetic nerve symptoms covers it in detail.

The one urgent case is swallowing far more than a dose at once: seizures and deaths have been described in case reports. If someone has a seizure or becomes confused after that, go to the emergency department now.

Educational content, not medical advice — consult a clinician.

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α-Lipoic acid (ALA)

Story

Connected to · 4

cofactor · 4

Niacin
On the two large enzyme complexes that feed fuels such as pyruvate into the citric acid cycle, lipoic acid acts like a swinging arm, passing the electrons stripped off the fuel through a riboflavin-based coenzyme to NAD⁺. NAD⁺ is made from niacin (vitamin B3) and is the last to take the baton in this relay.
Thiamin
Three enzyme complexes, pyruvate dehydrogenase, alpha-ketoglutarate dehydrogenase and branched-chain keto acid dehydrogenase, all need both thiamin (B1) and lipoic acid: B1 cuts a carbon-carbon bond in the fuel molecule, and lipoic acid passes the removed piece on to the next step. Without either one, these steps stall.
Riboflavin
The last subunit of these enzyme complexes takes the electrons from the lipoic acid arm and passes them first to FAD, then to NAD⁺. FAD is made from riboflavin (B2), so riboflavin runs the leg right after lipoic acid.
Pantothenic Acid
Pyruvate dehydrogenase uses both lipoic acid and coenzyme A: the two-carbon piece cut from pyruvate is handed by the lipoic acid arm to coenzyme A, forming acetyl-CoA, which can then enter the citric acid cycle. Coenzyme A is made from pantothenic acid (B5). The enzyme needs five helper molecules in all and stalls without any one of them.

Read full story

Stop 1/5

Soluble in both water and fat

EVIDENCEREVIEW 2

READ THE ORIGINAL

α-Lipoic acid () is a small molecule your body makes for itself. It is not a vitamin, and you cannot run short of it. Its real job in the body is to serve as a part on several mitochondrial enzymes that burn sugar for energy; the antioxidant effect sold on supplement labels is only a side job.

What makes it unusual is that it dissolves in both water and fat. Most antioxidants can work only in the watery part of a cell or only in the fatty part; ALA can get into both.

Your cells make it all the time, so there is no such thing as falling ill from a lack of it. Food holds only micrograms of it, while one supplement capsule holds several hundred milligrams, an amount no diet could supply. Calling it an essential nutrient is supplement marketing. The identity that does hold up is a different one: in Germany, China and some other countries it is a prescription drug for diabetic peripheral neuropathy (nerve damage in the feet and hands from high blood sugar, felt as numbness and prickling), and the evidence that it eases those symptoms comes from randomized trials. The chapter on easing diabetic nerve symptoms covers it in detail.

The one urgent case is swallowing far more than a dose at once: seizures and deaths have been described in case reports. If someone has a seizure or becomes confused after that, go to the emergency department now.

Educational content, not medical advice — consult a clinician.