Worried about body odor?

You are not alone. According to pre-COVID surveys, over one third said the fear of smelling unpleasant left them feeling unhappy and unattractive. Many people who survived COVID-19 worry about their body odor getting worse post-infection.

A team of researchers from Virginia Commonwealth University surveyed 322 individuals with loss of smell or taste as a result of confirmed COVID-19 infection and found that about half of them felt depressed and worried about their body odor [Coelho et al., 2021].  Extrapolating results of other surveys, this translates into about 20% of those who got through COVID-19.  

The most frequently reported phantom smell (likely not actually there) is the odor of smoke or burned food [Frasnelli et al, 2004]. Interestingly, these are also the most frequently reported types of smells that long-COVID sufferers can't perceive, when others detect them. 

Temporary loss of smell is common. About 20% of population experience it sometime before the age of 75. This number increases to ~80% in older age. 

Loss of smell associated with viral infections, especially COVID-19 is much more prevalent. Sometimes it's the only symptom associated with this infection. A meta-analysis of published reports reveals that the overall prevalence of alteration of the sense of smell or taste following COVID-19 infection ranges between 31% and 67% in severe and mild-to-moderate symptomatic patients, respectively. Fortunately, in most (70-80%) cases it comes back in 6 month or longer. A higher recovery rate was highlighted for subjects who underwent influenza vaccination. 

REFERENCES

Coelho DH, Reiter ER, Budd SG, Shin Y, Kons ZA, Costanzo RM. Quality of life and safety impact of COVID-19 associated smell and taste disturbances. American Journal of Otolaryngology. 2021 Jul 1;42(4):103001.

Frasnelli J, Landis BN, Heilmann S, Hauswald B, Hüttenbrink KB, Lacroix JS, Leopold DA, Hummel T. Clinical presentation of qualitative olfactory dysfunction. European Archives of Oto-Rhino-Laryngology and Head & Neck. 2004 Aug;261(7):411-5. 

Maiorano E, Calastri A, Robotti C, Cassaniti I, Baldanti F, Zuccaro V, Stellin E, Ferretti VV, Klersy C, Benazzo M. Clinical, virological and immunological evolution of the olfactory and gustatory dysfunction in COVID-19. American Journal of Otolaryngology. 2022 Jan 1;43(1):103170.

Vaira LA, De Vito A, Lechien JR, Chiesa‐Estomba CM, Mayo‐Yàñez M, Calvo‐Henrìquez C, Saussez S, Madeddu G, Babudieri S, Boscolo‐Rizzo P, Hopkins C. New onset of smell and taste loss are common findings also in patients with symptomatic COVID‐19 after complete vaccination. The Laryngoscope. 2021 Nov 26.

COVID-19 and vaccine reactogenicity in MEBO/PATM community

Infections have been shown to alter body odor and so have immunizations. So far, only nonhuman animals were able to detect the subtle changes in chemical makeup after vaccinations and even their sensitive noses were not able to differentiate between different vaccines - such as the rabies virus or the West Nile virus vaccines [Kimball et al, 2014]. However, this was the case of very mild reactions to immunization. Even slightly stronger inflammatory responses, to relatively weak immune challenges, can, indeed, be detected by human noses [Gordon et al, 2018]. Urine and axillary odor are becoming slightly more aversive in healthy humans, as a function of immune activation. But this is not supposed to last too long.

Our preliminary results, based on responses to the survey for 24 members of MEBO community and 6 of their family members show a wide variety of reactions to Astrazeneca, J&J, Moderna, Pfizer and Sinovac/Coronavac vaccines. 

Interestingly, Pfizer vaccine that caused no or very mild reactions in several MEBO participants, was also the vaccine that possibly caused temporary worsening of odor symptoms in one person in the community. Another MEBO participant that reported possible worsening of odor from Moderna vaccine had one thing in common with the other individual - they both had pre-existing conditions related to their upper digestive tract. Some Astrazeneca recipients also reported odor issues but did not think it was worse than usual. 

One of the most interesting observations was that even though only 2 members of MEBO/PATM community reported COVID-19 infection (before or between vaccinations), both of them had long COVID with long-term neurological manifestations such as fatigue, ENT symptoms and loss of smell.

Adverse reactions to COVID-19 vaccines are influenced by a multitude of factors, many of which can be anticipated and alleviated. A certain level of inflammation is needed to trigger an effective adaptive immune response, but both environment and genetic makeup determine who is more likely to experience particular symptoms after infection and from the vaccine.

You can help by telling us about your experiences with COVID-19 and/or vaccinations. These surveys can be used for posting your brief stories - no need to answer all the questions. And you can always add to your story later. Please use your anonymous ID and let us know if you have any questions.

Survey

in English:  https://bit.ly/BTN-eng

en Español: https:/bit.ly/BTN-esp

We'll be posting more observations and comparisons with over 600 participants of our study from other communities. 

REFERENCES

Blumental S, Debré P. Challenges and issues of anti-SARS-CoV-2 vaccines. Frontiers in Medicine. 2021;8.

Gordon AR, Kimball BA, Sorjonen K, Karshikoff B, Axelsson J, Lekander M, Lundström JN, Olsson MJ. Detection of inflammation via volatile cues in human urine. Chemical senses. 2018 Nov 1;43(9):711-9.

Kimball BA, Opiekun M, Yamazaki K, Beauchamp GK. Immunization alters body odor. Physiology & behavior. 2014 Apr 10;128:80-5.

Vaccine to cure body odor?

There could be a vaccine for everything. Scientists are working on personal vaccines, vaccines reducing body weight or narcotic dependence, vaccines for just about anything.  Can there be a vaccine improving body odor? Certainly, and it could target not only bacteria (in body crevices) worsening odor, but also molecules responsible for odor. This would be a very complex task, however, as there is still a lot we don't understand.  For example, if metabolism and microbiomes leading to body odor cause similar reactions to already existing vaccines. 

Several vaccines to prevent COVID-19 were authorized for emergency use and hundreds of millions doses have been administered. 2 millions of vaccinated individuals in the US completed a health survey in the 7 days following their vaccination via the v-safe app.

This table shows top adverse reactions reported to the first two vaccines authorized in the US. Hundreds of social media groups on Facebook, reddit and WhatsApp are also flooded by descriptions of adverse reactions and immunity related events. What is missing? The ability to systematically analyze all these reactions in different health and neighborhood communities.

We started such a study in one neighborhood community and would like to also conduct it in the MEBO/PATM communities. We are also opening it to MEBO friends and family - asking them to indicate their relationship with MEBO/PATM in the comment section of the survey.

We are also collecting COVID-19 experiences in different groups of people, analyzing infectious disease susceptibility risks. 

in English: https://bit.ly/BTN-eng

en Español: https:/bit.ly/BTN-esp

Thank you for your help!

REFERENCES

ClinicalTrials.gov [Internet]. Bethesda (MD): National Library of Medicine (US). 2021 April 6 - . Identifier NCT04832932, The COVID-19 Back-to-Normal Study [cited 2021 April 7]; Available from: https://clinicaltrials.gov/ct2/show/NCT04832932

Chapin-Bardales J, Gee J, Myers T. Reactogenicity Following Receipt of mRNA-Based COVID-19 Vaccines. JAMA. 2021 Apr 5. doi: 10.1001/jama.2021.5374. Epub ahead of print. PMID: 33818592. 

Zimmermann P, Curtis N. Factors that influence the immune response to vaccination. Clinical microbiology reviews. 2019 Mar 20;32(2). 

Mosquera MJ, Kim S, Zhou H, Jing TT, Luna M, Guss JD, Reddy P, Lai K, Leifer CA, Brito IL, Hernandez CJ. Immunomodulatory nanogels overcome restricted immunity in a murine model of gut microbiome–mediated metabolic syndrome. Science advances. 2019 Mar 1;5(3):eaav9788.

Bandaru P, Rajkumar H, Nappanveettil G. The impact of obesity on immune response to infection and vaccine: an insight into plausible mechanisms. Endocrinol Metab Synd. 2013;2(2):1000113-22. 

Kim YH, Kim JK, Kim DJ, Nam JH, Shim SM, Choi YK, Lee CH, Poo H. Diet-induced obesity dramatically reduces the efficacy of a 2009 pandemic H1N1 vaccine in a mouse model. Journal of Infectious Diseases. 2012 Jan 15;205(2):244-51. 

 Monteiro MP. Obesity vaccines. Hum Vaccin Immunother. 2014;10(4):887-95. doi: 10.4161/hv.27537. Epub 2013 Dec 23. PMID: 24365968; PMCID: PMC4896563. 

Ozgen MH, Blume S. The continuing search for an addiction vaccine. Vaccine. 2019 Aug 23;37(36):5485-90. 

Daniel W, Nivet M, Warner J, Podolsky DK. Early evidence of the effect of SARS-CoV-2 vaccine at one medical center. New England Journal of Medicine. 2021 Mar 23.

Microbial diagnostics of MEBO

There are many medical conditions for which there are no standard tests for definite diagnosis and no established cures.  Diagnosing and curing Metabolic Body Odor (MEBO) is even more difficult. Especially because MEBO is an umbrella term for several different conditions.

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Gender - confounder of concern?

Background and clinical characteristics measured at baseline are comparable in the groups of our study. But this doesn't eliminate the need to investigate the impact of confounding. We've already analyzed the effects of age, What about gender as a potential confounder?

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Reducing the stigma of odor disorders

Some conditions - such as obesity, depression and functional odor disorders - come with a social stigma. Understanding the etiology of these conditions helps to avoid stereotypes and find remedies. 

Metabolomics analysis of morning urine samples helped to evaluate the heterogeneity of MEBO population as good as challenge tests, procedures used to induce symptoms and assess resilience to perturbations caused by sugars. 


...  Read more ... 

Microbes of anti-social odor

Human odors depend on many extrinsic (such as food or clothing) and intrinsic factors - localized or systemic. In recent years, microbes responsible for localized malodors - bad breath caused by oral bacteria and axillary odor - have been mapped by using next generation sequencing approaches. However, intestinal microbes responsible for systemic malodor (whole-body and extraoral halitosis), remain to be identified.

 Our preliminary analysis of culture-, PCR- and 16S-RNA-based data donated by MEBO and PATM community members show that there are no easy answers.

Unraveling the Mysteries of Mischievous Microbiome

Science explains why some people smell worse than others despite keeping themselves squeaky clean.


  
The body is crawling with microbes that have evolved with the person, depending on the innate metabolism, history of infections, microbiome swaps, diet and lifestyle. The body's ecosystem of microorganisms can increase the risk for dangerous diseases for which we have unreserved levels of sympathy. It can also lead to ​unlikable conditions such as unpredictable and embarrassing outbursts of odor emitting through the pores - odor so bad it ruins social lives and careers.

Let those who never smelled bad cast the first stone

Analysis of our metabolism is crucial to comprehending the responses of our genes and microbes to the stresses of daily life, and to elucidating the causes and consequences of health and disease.

We applied metabolomic approach to an elusive condition that has always evaded diagnosis: socially and psychologically distressing odors that occur without a known or apparent cause. Learn about our preliminary results and participate in our anonymous survey to help us better understand and help with this condition.

Giving the underserved the care they deserve

Nobody likes strong smells coming from other human beings. It's just that social convention: you are nice, if you smell nice, and you are a monster - like Shakespeare's Caliban - if you smell bad.

But it could be the brunt of the genetic or environmental misfortune

Body Odor and Skin Bacteria

Our bodies are rainforests of microbes feeding off the leftovers from our meals and contributing to a variety of body odors. 

Human skin is inhabited and re-populated depending on health conditions, age, genetics, diet, the weather and climate zones, occupations, cosmetics, soaps, hygienic products and moisturizers. All these factors contribute to the variation in the types of microbes. Population of viruses, for example, can include a mixture of good ones - like bacteriophages fighting acne-causing Propionibacterium  - and bad ones  - as highly contagious Mesles. Bacterial communities include thousands of species of Actinobacteria, Bacteroidetes, Cyanobacteria, Proteobacteria, and fungi Malassezia.

Nat Rev Microbiol. 2011 April; 9(4): 244–253.

Nat Rev Microbiol. 2011 April; 9(4): 244–253.

These microbes form communities and have active social lives, cooperating to our good and bad experiences. They converse chemically - in many specific dialects and in universal Esperanto-like languages some of which even we could listen to  - by sampling and understanding smells. 

Humans are among the smelliest animals. And very capable in telling smells apart,  even if the only difference in two molecules is that their structures are mirror images of one another. But unlike dogs that appreciate a garbage bin as much as we appreciate the smell of fresh flowers, we don't properly interpret smells and like to complain about body odors. As we don't know all that much about chemical nature of our surroundings and rely on context and psychological factors, like feeling an intrusion in our experiences of the world. 

Maybe we have something to learn from the science of smells? 

In  a recent review of axillary microbiota, German researchers gave a good lesson in organic chemistry, listing major chemicals, enzymes and microbes responsible for body odor. Let's take a look. 

As was also shown in previous studies, Staphylococcus and Corynebacterium spp. are the most abundant organisms colonizing moist areas and emitting chicken-sulfury, onion-like and clary-sage like odors. The strain of Staphylococcus haemolyticus is producing some of the most offensive sulfury smells. Corynebacterium jeikeium K411 is another species that can compete on the strength of the odor. 

The major odor-causing substances are sulphanyl alkanols, steroid derivatives and short volatile branched-chain fatty acids. 

Most common sulphanyl alkanol in human sweat, 3-methyl-3-sulfanylhexan-1-ol is produced by bacteria in several ways, particularly in glutathione biodetoxification pathway, from molecules synthesized after consuming proteins (due to aminoacids L-cysteine, L-glutamic acid and glycin). This chemical,  besides being a major descriptor of human sweat odor,  is also present in beers. Its S-enantiomer (75%) is described as a classical body odor (sweat) with onion-like tones. Interestingly, the opposite enantiomer, (R)-3-methyl-3-sulfanylhexan-1-ol, is fruity and grapefruit-like. 

Another set of molecules produced by Corinebacterium are most prominent in Caucasian men and some Asians. The odor is hircine - resembling of goats with fatty and cheesy notes or cumin-spice like. The food sources contributing to this odor are proteins and animal fats. 

Pheromones androstenol and androstenone, metabolites of sexual hormones, are also odorous. The latter is especially interesting as to some of us it smells like vanilla while to others is smells like urine.

Sweaty-feet and cheesy smelling isovaleric and propionic acids and sour-vinegary acetic acid are also adding to the spectrum of human odors.  They can smell different to different people too - some people have genetic makeup making them hypersensitive to these smells, but others are much more tolerant and forgiving. The food sources of sourish smells are protein-rich. Lactic acid is found in cheeses, yogurt, soy sauce, sourdough, meats and pickled vegetables. It can be also produced from the breakdown of carbohydrates during exercise and used as additional fuel. Glycerol is created from triglycerides found in fats and oils.  

So next time you are exposed to body odor, try to understand what could be causing it. It is not easy as it is a combination of many factors such as hormonal fluctuations, mental or physical stress, metabolism and microbes. It could be perfectly normal or result from a medical condition of the person who has the smell and your own olfactory abilities. But the smells are fascinating clues to health and  the basics can be learned by most everyone.

REFERENCES

Fredrich E, Barzantny H, Brune I, & Tauch A (2013). Daily battle against body odor: towards the activity of the axillary microbiota. Trends in microbiology, 21 (6), 305-12 PMID: 23566668

Grice EA, & Segre JA (2012). The human microbiome: our second genome. Annual review of genomics and human genetics, 13, 151-70 PMID: 22703178

Stevenson, R., & Repacholi, B. (2005). Does the source of an interpersonal odour affect disgust? A disease risk model and its alternatives. European Journal of Social Psychology, 35 (3), 375-401 DOI: 10.1002/ejsp.263

Troccaz M, Starkenmann C, Niclass Y, van de Waal M, Clark AJ.  ( 2004) 3-Methyl-3-sulfanylhexan-1-ol as a major descriptor for the human axilla-sweat odour profile.Chem Biodivers. 2004 Jul;1(7):1022-35. PMID: 17191896

Lenochová P, Vohnoutová P, Roberts SC, Oberzaucher E, Grammer K, Havlíček J (2012) Psychology of fragrance use: perception of individual odor and perfume blends reveals a mechanism for idiosyncratic effects on fragrance choice. (PMID:22470479) Free full text article  PLoS One [2012, 7(3):e33810]

Barzantny H, Brune I, Tauch A. (2012) Molecular basis of human body odour formation: insights deduced from corynebacterial genome sequences. Int J Cosmet Sci. 2012 Feb;34(1):2-11. doi: 10.1111/j.1468-2494.2011.00669.x. Epub 2011 Jul 25.  PMID: 21790661

Odors and Infections

Many illnesses are associated with distinct odors. Especially those caused by infectious or opportunistic microbes inside the body or on its surfaces.  Body odor of someone infected with C. difficile, for example, can appear "swampy", Rotavirus gives sharply sweet putrid smell that some people associate with wet dogs. H. pylori can create a range of foul odors, and pseudomonas infections can smell like grapes and bitter almonds. 

Infections like C. difficile are usually linked to a general imbalance of the intestinal microbiota, often referred to as dysbiosis. This means that the odors could be coming from several microbial species, hence could be different for different individuals. Does it mean odor-based diagnostics will never be enough specific?

Not according to a 2-year-old beagle from Netherland, named Cliff. After just a little over two months of training, the beagle learned to identify the C. diff toxin by sniffing people or their samples. During one test, he was able to identify 25 out of 30 infected patients and 265 of 270 non-infected individuals. He also correctly identified 50 of 50 C. diff positive stool samples and 47 of 50 samples from people that did not have this infection. That's sensitivity of 100% for samples and 83-93% for sniffing the air around the patients, and a specificity of 94-100%! And it took him less than 10 minutes to accurately perform 300 diagnostic tests.  

Dogs already do the dirty work with detecting molds. They can examine an office building with 200 rooms in just 8 hours, a task that would take us several days of measuring  moisture, probably without any result. Electronic noses would be of great help and many years of research are finally being translated into useful technologies - to be integrated with refrigerators and mobile phones. But until we are able to build smart devices to detect odors without labor-intensive dog training, perhaps we could train our own nozzles. Studies have shown we do get better with practice. 


REFERENCES

Bomers MK, van Agtmael MA, Luik H, van Veen MC, Vandenbroucke-Grauls CM, & Smulders YM (2012). Using a dog's superior olfactory sensitivity to identify Clostridium difficile in stools and patients: proof of principle study. BMJ (Clinical research ed.), 345 PMID: 23241268

Poulton J, Tarlow MJ. (1987) Diagnosis of rotavirus gastroenteritis by smell. Arch Dis Child. 1987 Aug;62(8):851-2. PMID: 3662595

Arnaud Tognetti, Megan N Williams, Nathalie Lybert, Mats Lekander, John Axelsson, Mats J Olsson, Humans can detect axillary odor cues of an acute respiratory infection in others, Evolution, Medicine, and Public Health, Volume 11, Issue 1, 2023, Pages 219–228, https://doi.org/10.1093/emph/eoad016

Come out smelling like a rose

You are what you eat. And you smell like your food. Well, it's actually a bit more complicated - as we emit complex combinations of volatile chemicals produced from food by our own metabolic system as well as microbes that call us home. Same foods can be translated into a wide range of odors, depending on the individual. People exhibit a large variety of smells, much more diverse than animals or plants. Thanks to variations in our digestive enzymes, diets, supplements, medicines, perfumes, detergents, clothes, cars and a lot of other chemicals we are exposed to via different routes. And there are many ways to smell of a rose - for example, by putting a few petals in the pocket, wearing Sa Majeste La Rose or drinking rose oil.

As confirmed by gas-chromatograph mass spectrometry using a thermo desorption system and a selective ion mode (Akiyama et al., 2006), linalool, citronellol and geraniol, which are the main components of rose essential oil, are emitted from our palms after an oral intake of rose oil. The aroma starts to increase 30 minutes after ingestion and reaches its peak within an hour, then slowly decreases, wearing off more than 100 times in the next 6 hours. Citronellol seems to evaporate the fastest, and linalool lingers a little longer than the other two compounds, but, of course, this may very well differ for different individuals.

A new "functional food" - Deo Perfume Candy  - is an attempt to take the sciences of smells and foods to a whole new level by creating a sweet treat intended to make you smell good. The main active ingredient of this candies is Geraniol. It is extracted from rose oil, which in its turn is extracted from real rose petals - one gram of oil per two thousand petals. Small amounts of citric acid and tangerine oil are added for more flavor. An healthy food company Beneo partnered with Bulgarian candy maker, Alpi, to develop this nutricosmetics  treat. At present it is sold exclusively on Amazon and has already collected 5 reviews - ranging from a praise of the observed fresh-just-showered smell to complaints of the need to eat a buck load of candies to see some kind of effect. Does it really work? It might for some of us. With the right chemistry and metabolism, and the right combination of everything else. You can enter it in Aurametrix as Deo Perfume Candy and check back later to see how it worked for others. Or just log what you normally eat and wear to find how your body could react to Geraniol.

You might want to compare it with “Fuwarinka” or Otoko Kaoru's chewing gum - despite a name that translates to "man smell" it also contains rose-flavored geraniol. Although one tester reported to smell like an apple-flavored soap after chewing it.  You can also experiment with the "coming soon" edible perfume from Netherlands, and its mystery ingredient (transformed by the body enzymes and excreted through the skin’s surface through perspiration). There will be more to come.

The possibilities are endless and so are the human odor outcomes.

REFERENCES

AKIYAMA, A., IMAI, K., ISHIDA, S., ITO, K., KOBAYASHI, T., NAKAMURA, H., NOSE, K., & TSUDA, T. (2006). Determination of Aromatic Compounds in Exhalated from Human Skin by Solid-Phase Micro Extraction and GC/MS with Thermo Desorption System BUNSEKI KAGAKU, 55 (10), 787-792 DOI: 10.2116/bunsekikagaku.55.787

Studying body odor: one step at a time

Unpleasant body odors could be a sign of a disease. But even when the cause of the disease is known - an example is trimethylaminuria or TMAU - there are no one-size-fits-all solutions. Elimination of choline and other essential nutrients from diet can be harmful and unhelpful.  Everyone has their own unique needs, with individual combinations of foods, activities and optimal environmental conditions.

An earlier survey of about 100 body odor and halitosis sufferers indicated stress (34%), food (25%) and environment, including the weather and perfumed products (15%) as main triggers of odors. 23% of sufferers did not know what the trigger was.

Our study seems to have less unknowns. As you see from the picture, 60% of participants have both body odor and halitosis. Only 22% of participants were diagnosed with TMAU, one third has IBS, one third has environmental sensitivities (mostly pollen and mold allergies, but some have dust mite and pet allergies and chemical sensitivities). Over 60% of participants reported sensitivities to specific foods. Most frequent was lactose sensitivity.

It is known that a specific diet, infections and diseases have major impact on variations in human body odor.  Some of our early results on fatty and ammonia types of odors identified a few food ingredients and their maldigestion as potential causes. Our next posts on musty and smoky odors, as well as unpleasant odors in general will tell more.

e-mail to

 for more information

And stay tuned for results!

REFERENCES
Jan Havlicek, & Pavlina Lenochova (2008). Environmental effects on human body odour Chemical Signals in Vertebrates DOI: 10.1007/978-0-387-73945-8_19

Havlicek, J., & Lenochova, P. (2006). The Effect of Meat Consumption on Body Odor Attractiveness Chemical Senses, 31 (8), 747-752 DOI: 10.1093/chemse/bjl017

Moshkin M, Litvinova N, Litvinova EA, Bedareva A, Lutsyuk A, Gerlinskaya L. Scent Recognition of Infected Status in Humans. J Sex Med. 2011 Dec 6. doi: 10.1111/j.1743-6109.2011.02562.x.

What's that fatty odor?

Body odor is closely associated with diet. Deciphering the chemistry of human odor is not an easy task - only about 5% of odorous molecules are usually recovered from collection containers, and not all of the molecules are identified in complex spectra. Volatile fatty acids, alcohols, and aromatic ring compounds comprise a substantial fraction of smelly molecules, yet very little is known about the origin and factors controlling their production in humans. Fortunately for some (and not so fortunately for others), the human nose can capture and discriminate many smell signatures. Could this discrimination be used to connect the dots between diet and body odor? MEBO Research has just started an anonymous study using the Aurametrix health analysis tool to find out.

Aurametrix's knowledge base provides a wide selection of foods and symptoms, including different types of odors recognizable by the human nose. Participants in the study have been recording some of their food intake and activities on days when their symptoms are better or worse than average, entering items they suspect might be contributing to or alleviating their body odor on those days. The tool's analysis engine then lets them explore all the possible cause-effect relationships. In addition, Aurametrix performs automated analyses across the entire user community and displays cumulative results as "aggregate correlations." The figure on the right is an excerpt from these results.

Although the study has only just begun, the preliminary results already look very interesting. One example is fatty odor. Aurametrix linked several dietary chemicals to unpleasant "fatty odor" emanating from skin based on Aura entries of several participants. The top chemicals so far are:  Vitamin K1 (phylloquinone), Octadecanoic acid, FODMAPs, Beta-carotene,  Carbohydrates and Monosaccharides. Another interesting result (although there were fewer observations) is that Vitamin B12 obtained from diet seemed to help prevent fatty body odor.

• Could Vitamin K1 really contribute to "fatty" odor?  Could 6 observations derived from different users' Auras be just a coincidence? Vitamin K is proposed to increase production of alkaline phosphatase in intestines. This enzyme produces a number of different substances, some of which have a peculiar sweetish smell.  Chlorophyll, usually recommended to combat body odor and supposedly makes odor "sweeter," is an excellent source of vitamin K1. And so is Asparagus that gives urine a disagreeable odor.
• Octadecanoic (Stearic) acid was also linked to fatty odor in 6 observations. This saturated fatty acid is most abundant in animal fats and cocoa butter, and also in nuts and seeds (peanuts, flax), cheese, cookies and candies. Its smell is fairly mild, yet can be detected by the human nose (Bolton and Halpern, 2010). Besides, it slowly converts in the liver to heart-healthy oleic acid which has a faintly fatty odor with a hint of dead insects. It could also metabolize into other compounds and incorporate into liver lipids or follow alternative routes.
• FODMAPs, highly fermentable but poorly absorbed short-chain carbohydrates and polyols, were found to be an important dietary factor contributing to gastrointestinal symptoms. Perhaps FODMAPs, carbohydrates and monosacharides in particular could also contribute to odor in the absence of GI discomfort?
• Beta-carotene is another heart-healthy chemical with anticancerous properties important in human nutrition as a source of Vitamin A. Tobacco, tea, many spices and flowers owe their flavors to chemicals metabolized from beta-carotene. One of such chemicals is warm and woody beta-Ionone that smells of blackberry at lower concentrations and fatty-cheesy at higher concentrations.

The chemistry of odors and their origins is undoubtedly very complex. Yet, these preliminary results show that together we may find the answers to many health-related questions. With more participants, we'll soon connect the dots between diet and body odor. Want to participate? Write to:

References

Bolton B, & Halpern BP (2010). Orthonasal and retronasal but not oral-cavity-only discrimination of vapor-phase fatty acids. Chemical senses, 35 (3), 229-38 PMID: 20100787

Dunkel M, Schmidt U, Struck S, Berger L, Gruening B, Hossbach J, Jaeger IS, Effmert U, Piechulla B, Eriksson R, Knudsen J, & Preissner R (2009). SuperScent--a database of flavors and scents. Nucleic acids research, 37 (Database issue) PMID: 18931377

Colonoscopy for everyone! ..or Gonna Buy Me A Dog

New research from Japan brings good news: dogs can be almost as accurate as a colonoscopy exam.

In patients with colorectal cancer (CRC) and controls, the sensitivity of canine scent detection of breath samples compared with conventional diagnosis by colonoscopy was 0.91 and the specificity was 0.99.

The sensitivity of canine scent detection of watery stool samples was 0.97 and the specificity was 0.99.

The accuracy of canine scent detection was high even for early cancer. Canine scent detection was not confounded by current smoking, benign colorectal disease or inflammatory disease.  

As simple as that: exhaling 100-200 ml into a breath sampling bag and storing it in a Ziploc bag at 4°C until a trained dog has a change to sniff it can be enough for diagnostics. Just one breath sample! And it was almost as good as a watery stool sample obtained during colonoscopy or this joyous examination itself.

There have been many research studies that dogs, rats and even moth can detect scents pertaining to human disease. Ordinary household dogs can be trained to distinguish breath odors (McCulloch et al 2006). For some cancers, sensitivity can be as high as 100% (Horvath et al 2008).

Unfortunately, sophisticated mass-spectrometry, gas chromatography and software tools interpreting the signals are still not as good as our four-legged friends that are never getting lost in the noise of disease-unrelated flavors.
But we are getting better in identifying specific chemicals responsible for various conditions - from alkanes  - such as pentane in breath of IBD patients and polystyrene foam or aromatic components of petroleum in cancer breath to blends of fatty acids like oleic and linoleic acids forming the smell of death.

Perhaps pet rats will find their use as pocket doctors before men-made sensors are developed to cope with infections, medical conditions, even fear and anxiety that also have a distinctive odor signature. In any case, Dr. Sonoda and his colleagues bring us a reassuring word that not every frequent visitor to the GI doctor's office will have to experience the joys of a colonoscopy.


Sonoda H, Kohnoe S, Yamazato T, Satoh Y, Morizono G, Shikata K, Morita M, Watanabe A, Morita M, Kakeji Y, Inoue F, & Maehara Y (2011). Colorectal cancer screening with odour material by canine scent detection. Gut PMID: 21282130


Other published literature on olfactory signatures in gastrointestinal disease:

Cheu HW, Brown DR, Rowe MI (1989) Breath hydrogen excretion as a screening test for the early diagnosis of necrotizing enterocolitis. Am J Dis Child 1989;143:156–9.

Pelli MA, Trovarelli G,, Capodicasa E, Breath alkanes determination in ulcerative colitis and Crohn's disease. Dis Colon Rectum 1999;42:71–6.

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Tibble JA, Sigthorsson G, Foster R, Use of surrogate markers of inflammation and Rome criteria to distinguish organic from nonorganic intestinal disease. Gastroenterology 2002;123:450–60.

Hormonal Manipulation of Olfactory Cues, or How to Lose a Guy in 10 days

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Body odors are important cues used for social and sexual discrimination. As was shown many times, animals can easily smell age-, health- and genetics-related  differences.  Recent study of our large-eyed relatives, ring-tailed lemurs, demonstrate that drugs can alter body scents and change behavior.

Researchers examined changes in endocrine and  semiochemical profiles of sexually mature female lemurs treated with hormonal contraceptives during their breeding season. Genetic diversity and kinship were estimated using 11–14 microsatellite loci and pairwise genetic distances. Gas chromatography-mass spectrometry (GCMS) was used to detect the volatile compounds in odor. A rater blind to the treatments scored lemur male behavior in regards to female odors. 

The conclusion? Contraceptives change chemical ‘signature’, minimizing distinctiveness and genetic fitness cues. No more can the males determine which females are genetically and physically beautiful. All contracepted females lost their individuality and started to smell funny.  

What about hormones and chemicals in our food?  Maybe one day humans will wake up and realize that something is lost? May it will happen  sooner rather than later...

For those interested in helping with our research of human environmental malodor - check our studies or this call for collaboration.   



Jeremy Chase Crawford,, Marylène Boulet,, & Christine M. Drea (2010). Smelling wrong: hormonal contraception in lemurs alters critical female odour cues Proc. R. Soc. B published online before print July 28, 2010

Odor-prints: individual but genetic connections unclear

Odor is like fingerprints or facial features - it's unique.  Yet no single measurement could be easily applied to recognize an individual.

GC/MS measurements can be used to analyze mixtures of acids, alcohols, aldehydes, hydrocarbons, esters, ketones, and nitrogenous molecules in human odor. Complex algorithms mining patterns help to pinpoint the signatures. But could these signatures be easily derived from genetic makeups?

Recent article published in the Journal of Chemical Ecology looked at the usual suspects -  major histocompatibility locus (MHC) and found that these genes do not determine major patterns. 


Volatile carboxylic acids are the most diverse class of known axillary odorants, and the pattern of these acids is genetically determined. These acids  - like vast majority of human odorous compounds - are produced by human microbiome, in this case by skin bacteria. Odors of 12 families, comprising 3 to 6 siblings,were analyzed with comprehensive two-dimensional gas chromatography (GC x GC) and time-of-flight mass spectrometry (ToF MS). the analysis onfirmed the presence of individual signatures. but failed to find odors specific to HLA genes.

Even though paternally inherited HLA-associated odors were proposed to influence women odor preferences, genetic basis of odors may be more complicated than previously thought.

References

Natsch A, Kuhn F, & Tiercy JM (2010). Lack of Evidence for HLA-Linked Patterns of Odorous Carboxylic Acids Released from Glutamine Conjugates Secreted in the Human Axilla. Journal of chemical ecology PMID: 20623248

Thompson EE, Haller G, Pinto JM, Sun Y, Zelano B, Jacob S, McClintock MK, Nicolae DL, Ober C. (2010) Sequence variations at the human leukocyte antigen-linked olfactory receptor cluster do not influence female preferences for male odors. Hum Immunol. 2010 Jan;71(1):100-3. PMID: 19833159 
 
Jacob S, McClintock MK, Zelano B, Ober C (2002) Paternally inherited HLA alleles are associated with women's choice of male odor. Nature Genet 30: 175-179  PMID: 11799397  PDF