News & Views on Systemic Body Odor and Halitosis such as trimethylaminuria TMAU. If you have fecal odors or bowel odors it may be metabolic/systemic

23 November 2011

What other enzymes could be a problem in fecal body odor ?

My energy has mainly gone in to believing that FMO3 enzyme is the chief suspect, mainly because it oxidizes such a wide range of sulfides and amines (and phosphorous containing compounds too)

But at this stage I am speculating and it would be wrong to rule out anything yet. So what other enzymes could be responsible or play a part in 'fecal body odor syndrome' ?

Methionine cycle :
methionine is one of the 2 main sulfur amino acids we need, and end products will be pretty 'sulfury'. There is a methionine cycle where it is recycled, which involve a number of enzymes. Of special interest is the Methionine adenosyltransferase enzyme, because this is documented as being associated with an odor wihtout any other health problem. Other enzymes in the cycle are associated with other serious health problems. Apparently the person is supposed to have a 'boiled cabbage odor', thought to be caused by dimethyldisulfide. Whether it can explain the wide range of 'fecal odors' is not known. However I do have an aversion to sulfury things.

Further down the Methionine breakdown pathway :
When it is not recycled, methionine can end up going down a pathway where a lot of sulfury things seem to be produced. Hydrogen Sulfide, Dimethyldisulfide, thiosulfates etc. Certainly worth keeping an eye on.

Xenobiotic metabolizing enzymes :
Enzymes that deal with 'external compounds' are often labelled as XME's. Usually the enzymes also deal with internal compounds, so have a dual function. FMO3 is regarded as one of these enzymes, along with a number of 'phase 2' conjugating enzymes. The main family of the XME's is the CYP450 group of enzymes. This is where most interest in the pharmacolgy industry is. It seems likely that most people have various capacity of these enzymes (eg 95%, 90%,80%), which could be a problem with big loads that are best suited for these pathways. The theory is that loads for CYP450 and FMO3 can go alternative slower routes (apart from TMA in the case of FMO3), and so no build up will happen. But this is unlikely. If you think of it as a highway with a lane shut off. If the traffic builds up too much, you can go different routes, but if a lane is shut off in them too, then you have a log jam.

It seems that most XEMs were also prone to modulation by compounds which in most cases would 'reduce' their function (inhibit). Grapefruit is known to inhibit the CYP3A4 enzyme present in the gut. Until recently it was thought that FMO3 could not be inhibited but it now seems to me unlikely that this is the case. Indoles in cruciferous veg have already been shown to inhibit FMO3. I'm sure there will be other compounds, perhaps even internal compounds such as biogenic amines that make up hormones.

So, the make up of a person's XEMs could play a role. If you have a lane closed in your FMO3 pathway, and a lane closed in an alternative CYP pathway, it could mean you don't handle FMO3 traffic well.

At the moment I am not too interested in other enzymes, since my feeling is that other enzymes will produce a limited 'certain' odor, such as the sweaty feet smell of isovaleric acidemia. But I could be wrong.


TMAU Stories

Get New Posts by Email

systemic BO/halitosis important links

MEBO Research malodor study 2016


FMO3 reference

Blog Archive

TMAU/FMO3 research

Systemic Body Odor links

email :

Do you have systemic body odor ?

FMO3 Survey Form

FMO3 DNA test result survey
for those who have FMO3 DNA tested
survey still OPEN

TMA blocker pill (links)

P&G - Cleveland press release aug 2015
1st mention of 'DMB pill' dec 2015
FMO3 DNA testing
Update Aug 17 :
Genos is back with it's EXOME test

Note :
Exome/Genome testing may be better option than single gene testing.

See this post : link

Note : Genos Exome Testing.

Exome testing is almost the same price now as single gene testing. Also Genos is consumer friendly, which standard DNA labs are not.

So the blog offer to test solely for FMO3 is almost obsolete, and so no longer offered.

Does Genos fully sequence FMO3 gene ?

At the moment it is not clear, but hoped this will become clear over the next few months

Note : possible 'wild west' way of testing FMO3
Use an ancestry dna site and rummage through the raw data

TMAU Webinar #5 : Preti et al