Quantification of Allyl Methyl Sulfide, Allyl Methyl Sulfoxide, and Allyl Methyl Sulfone in Human Milk and Urine After Ingestion of Cooked and Roasted Garlic.

Due to its characteristic flavor and positive effects on human health, garlic is a highly valued food ingredient. Consumption of garlic alters the quality of body odors, which may in some instances hinder social interaction but be beneficial in other contexts, as it is assumed to contribute to early flavor learning in the breastfeeding context, for example. In previous work, allyl methyl sulfide (AMS) has been identified as the major odor-active metabolite in urine and milk, being excreted together with the odorless metabolites allyl methyl sulfoxide (AMSO) and allyl methyl sulfone (AMSO2) after ingestion of raw garlic. The present work aimed to elucidate whether commonly used culinary thermal processing steps influence the excretion profiles of garlic-derived compounds. To this aim, urine (n = 6) and milk (n = 4) samples were donated before and after ingestion of roasted and cooked garlic and investigated by gas chromatography-olfactometry/mass spectrometry, and, in the case of milk, by aroma profile analysis. The concentrations of AMS, AMSO, and AMSO2 were determined by stable isotope dilution assays. Sensory evaluations revealed that a garlic-like odor was perceivable in milk samples donated after ingestion of roasted and cooked garlic. Besides AMS, AMSO, and AMSO2, no other odor-active or odorless compounds related to the ingestion of roasted or cooked garlic were detected in the urine and milk samples. Maximum concentrations of the metabolites were detected around 1-2 h after garlic intake. In some cases, a second maximum occurred around 6 h after ingestion of garlic. The cooking procedure led to a more important reduction of metabolite concentrations than the roasting procedure. These findings suggest that intake of processed garlic leads to a transfer of odor-active and odorless metabolites into milk, which contributes to early flavor learning during breastfeeding and may also have a physiological effect on the infant.

Quantification of Volatile Metabolites Derived From Garlic (Allium sativum) in Human Urine.

The consumption of garlic (Allium sativum) is widely known to (negatively) impact body odor, in particular breath and sweat, but also urine. Despite this common phenomenon, the underlying processes in the body that lead to the malodor are not yet fully understood. In previous studies we identified three volatile garlic-derived metabolites in human milk and urine, namely allyl methyl sulfide (AMS), allyl methyl sulfoxide (AMSO), and allyl methyl sulfone (AMSO2). In the present study, we monitored the excretion processes of these metabolites via human urine after consumption of garlic over time, whereby 19 sets of eight urine samples (one sample pre-ingestion and seven samples post-ingestion) were analyzed using two-dimensional high resolution gas chromatography-mass spectrometry/olfactometry (HRGC-GC-MS/O). The highest concentrations of these metabolites were detected in urine ~1-2 h after garlic ingestion, with a second increase observed after 6-8 h in the urine of some participants. Moreover, the highest observed concentrations differed between the individual participants or test series by up to one order of magnitude.

Quantification of volatile metabolites derived from garlic in human breast milk.

Maternal garlic intake during pregnancy and the breastfeeding period has been reported to be associated with the potential of modulating later garlic acceptance in infants. However, the metabolism of garlic constituents in humans and their elimination and potential excretion into human milk are not yet fully understood. In previous studies, we identified volatile garlic-derived metabolites in human milk as well as in human urine, namely allyl methyl sulfide, allyl methyl sulfoxide and allyl methyl sulfone. To monitor the excretion of these garlic metabolites in a larger cohort, we quantified these metabolites in a total of 18 human milk sets, whereby each set comprised of one sample collected before and three samples after garlic consumption. The analyses revealed that the concentrations of the metabolites were most abundant 1-3.5 h after garlic consumption, with distinct differences between test persons regarding metabolite concentrations as well as temporal excretion.

Identification and Quantification of Volatile Ramson-Derived Metabolites in Humans.

Ramson (Allium ursinum) is known for its typical garlic-like aroma. Both ramson and garlic belong to the genus allium which is characterized by a high content of sulfurous compounds. However, in contrast to garlic, ramson is in general not associated with an unpleasant breath following consumption. While there is data available regarding the metabolism of volatile garlic constituents in the human body, the metabolism of ramson was not yet addressed. To elucidate if ramson has an impact on the body odor, this study aimed at identifying volatile ramson-derived metabolites in human milk and urine. Therefore, milk and urine samples were gathered before and after ramson consumption, and were analyzed sensorially by a trained human sensory panel as well as chemo-analytically applying gas chromatography-mass spectrometry/olfactometry (GC-MS/O). Sensory evaluation revealed a garlic-/cabbage like odor in milk samples obtained after ramson consumption, demonstrating that ramson consumption affected the milk aroma. Analyzes by means of GC-MS/O further confirmed excretion of three ramson-derived metabolites in milk and urine samples collected after ramson consumption, namely allyl methyl sulfide (AMS), allyl methyl sulfoxide (AMSO) and allyl methyl sulfone (AMSO2). Of these metabolites only AMS had a garlic-/cabbage-like odor, while the other two were odorless. These metabolites were subsequently quantified using stable isotope dilution assays. Nine urine sets, each comprising eight urine samples, and nine milk sets, each comprising four samples, were analyzed. In case of the urine sets a time interval of about 24 h was monitored, in case of the milk sets a time interval of up to 9 h. Despite the fact that all samples contained the same metabolites there were relevant differences found between individual subjects, especially with regard to the temporal rate of metabolite excretion. Generally, the maxima of metabolite excretion were observed in milk sets within 3 h after ramson consumption. In urine the highest AMS and AMSO amounts were observed within 2 h whereas the maximum concentration of AMSO2 was reached about 2 to 4 h after ramson ingestion. This study suggests that ramson constituents are heavily metabolized in the human body.

Responses of Human Neonates to Highly Diluted Odorants from Sweat.

Conjugated forms of odorants contributing to sweat odor occur not only in human sweat but also in amniotic fluid, colostrum, and milk. However, it is unclear whether the released odorants are detected and hedonically discriminated by human newborns. To investigate this issue, we administered highly diluted solutions of (R)/(S)-3-methyl-3-sulfanylhexan-1-ol (MSH), (R)/(S)-3-sulfanylhexan-1-ol (SH), (E)/(Z)-3-methylhex-2-enoic acid (3M2H), and (R)/(S)-3-hydroxy-3-methylhexanoic acid (HMHA) to 3-d-old infants while their respiratory rate and oro-facial movements were recorded. Adult sensitivity to these odorants was assessed via triangle tests. Whereas no neonatal stimulus-specific response was found for respiratory rate, oro-facial reactivity indicated orthonasal detection of MSH and SH by male neonates, and of HMHA by the whole group of neonates. Dependent on the dilution of odorants, newborns evinced neutral responses or longer negative oro-facial expressions compared with the reference stimuli. Finally, newborns appeared to be more sensitive to the target odorants than did adults.

Detection of Volatile Metabolites Derived from Garlic (Allium sativum) in Human Urine.

The metabolism and excretion of flavor constituents of garlic, a common plant used in flavoring foods and attributed with several health benefits, in humans is not fully understood. Likewise, the physiologically active principles of garlic have not been fully clarified to date. It is possible that not only the parent compounds present in garlic but also its metabolites are responsible for the specific physiological properties of garlic, including its influence on the characteristic body odor signature of humans after garlic consumption. Accordingly, the aim of this study was to investigate potential garlic-derived metabolites in human urine. To this aim, 14 sets of urine samples were obtained from 12 volunteers, whereby each set comprised one sample that was collected prior to consumption of food-relevant concentrations of garlic, followed by five to eight subsequent samples after garlic consumption that covered a time interval of up to 26 h. The samples were analyzed chemo-analytically using gas chromatography-mass spectrometry/olfactometry (GC-MS/O), as well as sensorially by a trained human panel. The analyses revealed three different garlic-derived metabolites in urine, namely allyl methyl sulfide (AMS), allyl methyl sulfoxide (AMSO) and allyl methyl sulfone (AMSO2), confirming our previous findings on human milk metabolite composition. The excretion rates of these metabolites into urine were strongly time-dependent with distinct inter-individual differences. These findings indicate that the volatile odorant fraction of garlic is heavily biotransformed in humans, opening up a window into substance circulation within the human body with potential wider ramifications in view of physiological effects of this aromatic plant that is appreciated by humans in their daily diet.

Detection of Volatile Metabolites of Garlic in Human Breast Milk.

The odor of human breast milk after ingestion of raw garlic at food-relevant concentrations by breastfeeding mothers was investigated for the first time chemo-analytically using gas chromatography-mass spectrometry/olfactometry (GC-MS/O), as well as sensorially using a trained human sensory panel. Sensory evaluation revealed a clear garlic/cabbage-like odor that appeared in breast milk about 2.5 h after consumption of garlic. GC-MS/O analyses confirmed the occurrence of garlic-derived metabolites in breast milk, namely allyl methyl sulfide (AMS), allyl methyl sulfoxide (AMSO) and allyl methyl sulfone (AMSO2). Of these, only AMS had a garlic-like odor whereas the other two metabolites were odorless. This demonstrates that the odor change in human milk is not related to a direct transfer of garlic odorants, as is currently believed, but rather derives from a single metabolite. The formation of these metabolites is not fully understood, but AMSO and AMSO2 are most likely formed by the oxidation of AMS in the human body. The excretion rates of these metabolites into breast milk were strongly time-dependent with large inter-individual differences.