Suberate (suberic acid)

Suberate, the salt of suberic acid (octanedioic acid), is a dicarboxylic acid with eight carbon atoms – an organic acid formed during the breakdown of fatty acids. Suberate is measured in urine. In the evidence profiles on burnout, exhaustion, stress, depression, long/post-COVID and migraine it belongs to the group “mitochondrial dysfunction”, together with lactate, pyruvate, citrate and L-carnitine. Small amounts are excreted all the time. The value shows whether the mitochondria keep up with the breakdown of fatty acids or whether the body falls back on an alternative route.

How suberate is formed in the body

Fatty acids are one of the most important energy sources, especially for the heart and muscles. Normally they are channelled into the mitochondria with the help of L-carnitine and broken down there step by step in β-oxidation into acetyl-CoA, which enters the citric acid cycle. Among other things, this requires vitamin B2 in the form of FAD and vitamin B3 in the form of NAD. If more fatty acids arrive than the mitochondria can process, or if β-oxidation is slowed, enzymes in the endoplasmic reticulum oxidise the fatty acids from the other end (ω-oxidation). This produces dicarboxylic acids, which are shortened in the peroxisomes – to adipic acid, suberic acid and sebacic acid, which are excreted in urine.

Raised suberate – what happens in the body?

A raised value shows that the alternative route is being used more. This can have two reasons: particularly large amounts of fatty acids are released – for example during fasting, with a very low-carbohydrate, ketogenic diet, with prolonged physical exertion, with poorly controlled diabetes or after eating medium-chain fats (MCT oil). Or β-oxidation in the mitochondria is slowed, for example with a lack of L-carnitine or vitamin B2 or – rarely – with congenital disorders of fatty acid breakdown. In the second case the cells gain less energy from fat and depend more on sugar. This can show as rapid exhaustion, low exercise tolerance and muscle weakness. Lactate, pyruvate and carnitine help with interpretation.

Low suberate – what does it mean?

A low value is the normal case. It shows that the mitochondria cope with the fatty acids arriving via β-oxidation and that the alternative route via ω-oxidation is hardly needed. An independent meaning of very low values has not been established scientifically. Because excretion depends strongly on how many fatty acids are currently being broken down, the circumstances of sampling also play a role: after a carbohydrate-rich meal the body mainly uses sugar, and little suberate is formed. The value is therefore considered not on its own but together with the other markers of energy metabolism.

The interpretation is given in your report.