About Metabolic Body Odor

Metabolic body odor occurs when one or more of our internal cell enzyme(s), such as the Flavin containing mono-oxygenase3 (FMO3) metabolic enzyme, is deficient and is thus easily saturated with its substrate rendering the enzyme unable to complete its metabolic process of oxidizing the substrate to it's non-odorous state. Consequently, a significant amount of the odorous unmetabolized volatile organic compound (VOC) buildsup up in the body.  Trimethylaminuria (TMAU), Dimethylglycinuria, Isovaleric Acidemia, and others yet to be named with further research, are examples of this condition.  Metabolic body odor conditions are the result of genetic faults which causes a deficiency in one or more cell enzymes, the main enzyme affecting body odor conditions seems to be the group of xenobiotic metabolizing enzymes, particularly the (FMO3) enzyme, according to most professional literature. This condition 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 of a metabolic source as well, with the toxins exiting via the alveolar breath from the lungs. 

This faulty biochemical process, results in unmetabolized odorous volatile organic compounds (VOCs) being in the bloodstream and exiting throughout the body's cleansing organs. Normally someone with a metabolic odor condition will release the toxin from his or her body in various ways; for instance, the body will remove these VOCs through the skin's perspiration and oils, alveolar breath (from the lungs), saliva, mucous, urine, any other body fluids that produce an aura of very embarrassing and socially disruptive odor.

 However, this does not necessarily mean that all persons affected with body odor are low in the metabolic enzyme(s) in question, although some do have a milder form of the condition, resulting in more intermittent symptoms.  Nonetheless, other persons affected with body odor who have normal metabolic enzyme levels may also have odorous unmetabolized biochemicals in the body as result of a very high ingestion of the substrate and/or increased microbial overgrowth in the gut that produces an excess amount of the substrate, which the normal enzyme levels are not able to oxidize resulting in an accumulation of odorous compound(s) in the system. For example, many people often smell of garlic after garlic ingestion. The reason being there is an excess of the garlic-derived sulfur-based compounds that the cell enzymes are unable to break down to a non-odorous state; therefore, these malodorous compounds enter the main circulation unprocessed and exit through the skin perspiration and oils, alveolar breath, saliva, urine, and other body fluids.  

Other persons have uncontrollable localized odor, such as bromhidrosis in the axillae, groin area, feet, and other parts of the body that may not be due to a metabolic source.

It has also been observed and documented that hormonal changes trigger odor flare ups, as seen in women during their menstrual cycle, increased levels of adrenaline during stress, and others.

Reasons for metabolic body odors :
One or more cell enzymes not functioning at normal levels : This could be due to a metabolic disorder inherited in an autosomal recessive manner, such as in Primary Trimethylaminuria, where the person shows to not have normal capability of oxidizing odorous trimethylamine (TMA) into non-odorous trimethylamine-n-oxide (TMAO) due to genetic causes. Normally they will have some degree of substrate oxidizing capability by the metobolic enzyme, such as 50%, 60%, 90% etc. Although in theory metabolic body odor conditions could be caused by deficiency in one of many cell enzymes, the main enzyme suspects (until ruled out by much needed additional research) would seem to be the group of xenobiotic metabolizing enzymes, especially the Flavin Monooxygenase 3 (FMO3) enzyme.  

Abnormal amounts of odorous volatile organic compounds being absorbed into the bloodstream and transported throughout the body : This is when the person is absorbing too many odorous compounds into the main circulation, basically overloading the enzymes that usually oxidizes 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 the case of a microbial imbalance in the gut in Secondary Trimethylaminuria, certain types of bacteria turn choline into TMA, which is then adsorbed into the bloodstream saturating the body with high levels of TMA substrate that normal levels of metabolic enzyme, FMO3, is unable to oxidize.   

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

Types of metabolic body odors 

Trimethylaminuria :  Currently Trimethylaminuria (TMAU) 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 Dimethylglycinuria (DMGU), 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 and other odorous volatile organic compounds may be found in individuals. Unfortunately in practice, TMAU is the only test that only a few physicians 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 blog.

Fecal Body Odor : This is by far the most common type of metabolic body odor problem mentioned on body odor forums, even amongst those diagnosed for Primary and Secondary Trimethylaminuria (TMAU1 and TMAU2), and possibly even the main form of body odor worldwide. 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 an unresearched medical 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 others. Perhaps people use the term fecal body odor because this is the odor associated with the most socially hurtful remarks (and also the most confusing), or perhaps because feces contains a combination of odors and body odor conditions, probably involving more than one odorous biochemical.  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 it is an obvious main suspect, although perhaps more enzymes could be involved. Research of Fecal Body Odor has been unresearched because it would be very costly to do so, as research would involve multiple 'fronts' including a deeper understanding of the various genetic faults resulting in the various metabolic enzyme deficiencies, as well as involving the proper identification and quantification of possible contributing microorganisms that produce high levels of odorous volatile organic compounds.