About Metabolic Body Odor

Metabolic body odor occurs when one or more of our internal cell enzyme(s) (for example the Flavin containing mono-oxygenase 3 metabolic enzyme) is saturated by one or more smelly compounds that would normally be neutralized (in the case of FMO3, by oxidation) by this enzyme(s). This results in an unmetabolized compound entering the main circulation and exiting throughout the body.  It can also be termed as 'systemic body odor' or 'bloodborne body odor' or 'cell-enzyme saturated body odor' or other various names of the same concept. It is possible that some forms of halitosis may be metabolic sourced as well, with the toxins exiting via the alveolar breath from the lungs.

Normally someone with a metabolic odor condition will release the toxin in any way possible, for instance through the skin perspiration, through the alveolar breath (from the lungs), urine etc. This does not necessarily mean that the person is low in the enzyme(s) involved; it can be because they are consuming, absorbing, or producing too much of the smelly compound(s) that the enzyme levels are not able to neutralize (e.g. oxidizing trimathylamine). For example, many people often smell of garlic after garlic ingestion; the reason being there is an excess of the garlic compounds and the cell enzymes are unable to break down the amount; and so these odorous compounds enter the main circulation unprocessed and exits through the skin, breath, urine etc. However, with those who feel they have an ongoing metabolic body odor issue that affects their life, it seems likely there may be a genetic aspect to this, even if only slightly.

Reasons for metabolic body odors :
One or more cell enzymes not functioning at normal levels : This could be due to a genetic weakness, such as in primary Trimethylaminuria, where the person shows to not have normal capability of neutralizing odorous trimethylamine into non-odorous trimethylamine-n-oxide. Normally they will have some capability, such as 50%, 60%, 90% etc. Although in theory it could be one of many cell enzymes, the main suspects (until ruled out) would seem to be the group of xenobiotic metabolizing enzymes, especially the Flavin Monooxygenase 3 (FMO3) enzyme.  

Abnormal amounts of smelly volatile organic compounds being absorbed into the bloodstream and transported throughout the body : This is when the person is absorbing too many smelly compounds into the main circulation, basically overloading the enzymes that usually neutralize such compounds. An example of this would be smelling of curry or garlic after eating such foods. Secondary Trimethylaminuria is another example, involving a microbial imbalance, or dysbiosis.

In practice, possibly many people are a little of both the above, with the main factor being of a genetic cause, and the other factor having to do with treatable issues, such as gut dysbiosis. At the moment, metabolic body odor is not accepted as a problem by the main medical system, apart from Trimethylaminuria, which only a small amount of doctors would have heard of.

Types of metabolic body odors 

Trimethylaminuria :  Currently Trimethylaminuria is the only recognized metabolic body odor syndrome (also termed a condition or disorder) that has been documented by more than one researcher.  More can be read about TMAU on the Trimethylaminuria page of this website.

dimethylglycinuria : Only one research paper has ever been done on this, although it seems to be tested for by one or more testers. However, if metabolic body odor syndromes would be fully studied by researchers using a full volatile organic compound test, it would likely show that many more of these smelly compounds may be found in individuals. Unfortunately, TMAU is the only real test that the few testers prescribe (and some also test for DMGU), rather than a full malodorous VOC test.  Dimethylglycine is also said to have a 'fishy' smell.

Isovaleric acidemia :  This is a very serious metabolic disorder usually due to lack of the enzyme Isovaleryl coenzyme A dehydrogenase. One of the tell-tale symptoms is a sweaty feet body odor due to high levels of isovaleric acid. However, it seems probable that people with borderline 'variants' or carriers may possibly have just a transient problem with the sweaty feet odor and no other obvious symptoms. However, on the body odor forums, such cases do not seem to be common.  Link : Sweaty feet syndrome post on the MeBO sister blog

Fecal Body Odor : This is by far the most common type of metabolic body odor problem mentioned on body odor forums, and possibly even the main form of body odor. MeBO intends to focus on this syndrome in particular, since it is the most common and needs to be defined. At the moment, this body odor is a mystery. It appears that it may not be an entirely precise label, since the sufferers seem capable of a wide range of smells that also include gas, sewage, garbage, rotten egg, and many more. Perhaps people use the term fecal body odor because this is the odor associated with the most hurtful remarks (and also the most confusing).  Since there are so many smells involved, it seems the main suspect would be one or more saturated xenobiotic metabolizing enzyme(s), since these enzymes deal with a multitude of 'substrates', including toxins. FMO3 is one such enzyme of this group, and so an obvious main suspect, although perhaps more enzymes could be involved.