Health ConditionsBromhidrosis, also known as osmidrosis or ozochrotia, is an unpleasant or offensive body odour due to any cause, including poor hygiene, infections, diet or medications, or inherited metabolic disorders. While it is primarily regarded as a cosmetic and social concern, strong or unpleasant body odor can lead to psychological consequences; individuals affected by unpleasant body odor may avoid social interactions, resulting in anxiety, reduced self-esteem, and a diminished quality of life.
Bromhidrosis can affect all age groups, races, and both sexes. It is more common in adults than children, as sebaceous glands and apocrine sweat glands do not become active until puberty. The elderly have a different body odour from babies, pre-pubescent children, teenagers, and adults. It has a male predominance and can be a particular issue in hot, humid, tropical climates. There may be a genetic predisposition, with studies suggesting axillary malodour is more common in Europeans and Africans than Asians.
Bromhidrosis is classified into two main forms based on the gland of origin:
There are three main types of sweat gland, each producing slightly different fluids. Eccrine glands sit across most of the body and release a thin, watery sweat made mostly of water and salt. Apocrine glands, found mainly in the armpits and groin, produce a thicker fluid that contains fats, proteins, and sugars. Apoeccrine glands, also concentrated in the armpits, produce sweat that is more similar to the watery type but in larger amounts.
Apocrine glands produce an odorless fluid composed of proteins, lipids, fatty acids, branched-chain amino acids, vitamins, and steroids, which is discharged into the canals of hair follicles. Eccrine sweat — clear, odorless, with a pH of 4.0–6.8 — is composed of 98–99% water but also contains sodium chloride, fatty acids, lactic acid, citric acid, ascorbic acid, urea, and uric acid. Apocrine sweat, which is also odorless, has a pH of 6.0–7.5 and contains water, proteins, carbohydrates, lipids, and steroids.
Furthermore, sebaceous glands that secrete an odorless oily matter called sebum into hair follicles (pH 4.5–5.5) have increased activity during puberty. Body odor is generally considered significant only in post-pubescent subjects and adults, and has primarily been studied within the axilla, where apocrine glands outnumber eccrine glands by a factor of 10.
Sweat production is controlled by the autonomic nervous system, which regulates automatic bodily functions such as temperature and heart rate. Thermoregulatory sweating by the eccrine sweat glands is primarily activated by an increase in body temperature induced by an increase in metabolic and/or movement energy and/or ambient temperature. Psychological stress activates the sympatho-adreno-medullary system and activates sweat production by the apocrine glands.
It is now generally accepted that skin bacteria cause body odor by biotransformation of sweat components secreted in the human axillae. The generation of body malodor results from the conversion of odorless precursor molecules, naturally secreted by various glands (apocrine, eccrine, and sebaceous), into volatile odorants by the skin's commensal microbiota. Differences in microbiome composition across the skin, together with site-specific variations in apocrine, eccrine, and sebaceous gland density, determine the types and amounts of malodor precursors available.
It is not until the apocrine sweat is metabolized by axillary microorganisms such as Micrococcaceae, Propionibacteria, Staphylococcus, and nondiptheroid Corynebacterium species that it develops its characteristic odor.
The body can emit odorous substances (odorants) with breath, saliva, sweat (skin), urine, or reproductive organ fluids. The major odorants are small, volatile compounds that may either be produced in situ (skin, oral cavity) or be carried by blood from the gut, which is a major site of bacterial metabolism. The accumulation of odorous compounds might result from diet, specific composition of microbiota, as well as compromised function of the liver, intestines, and kidneys.
Analysis of odoriferous sweat components has shown that the major odour-causing substances in human sweat include steroid derivatives, short volatile branched-chain fatty acids, and sulphanylalkanols.
A major odorant responsible for the onion-like malodor is generated mainly by Staphylococcus hominis, and is composed of volatile sulfur compounds such as 3-Methyl-3-sulfanylhexanol. These volatile sulfur compounds are secreted by apocrine glands as glycine-cysteine conjugates and are enzymatically cleaved by bacterial dipeptidases and C-S lyases, which release odoriferous mercaptoalcohols.
Other malodors include the volatile fatty acid 3-methyl-2-hexenoic acid (3M2H), which has a goat-like odor, and 3-methyl-3-hydroxy-hexanoic acid, which has a cumin-like odor. Studies indicate that 3M2H is released from the skin surface after interacting with Corynebacterium striatum and Corynebacterium bovis.
Bacteria break down apocrine sweat into numerous volatile molecules such as ammonia and short-chain fatty acids, e.g., (E)-3-methyl-2-hexenoic acid (E3M2H), which is a C7 branched and unsaturated acid. It has been reported to have a very strong, pungent odor.
Metabolic pathway analysis has highlighted the association of isovaleric and acetic acid production (sour odor) from enriched S. epidermidis enzymes (teen underarm) and S. hominis (child neck), and sulfur production from Staphylococcus species (teen underarm) with odor intensity, in good agreement with observed odor characteristics in pre-pubescent children and teenagers.
The disease of bromhidrosis or osmidrosis (excessive axillary and body malodor) is associated with GG and GA genotypes of the ABCC11 gene, which governs apocrine gland function. Apocrine glands are inactive until stimulated by hormonal changes in puberty, and unlike eccrine glands, which secrete continuously, apocrine glands secrete periodically.
Some people sweat excessively without heat or exercise. This condition, known as hyperhidrosis, affects around 2% of the population and often requires medical treatment rather than improved hygiene alone. Hyperhidrosis significantly increases the substrate available for bacterial metabolism, amplifying malodor.
During times of emotional stress (such as anxiety, fear, or excitement), the body activates the sympathetic nervous system, which in turn stimulates apocrine sweat glands. There is a dose-response relationship between stress intensity and stress sweating: the greater the stress, the greater the sweat.
Trimethylaminuria, or fish odor syndrome (FOS), is a condition characterized by the presence of trimethylamine (TMA) — a tertiary amine whose odor is described as resembling that of rotting fish — in the urine, sweat, and expired air. Primary trimethylaminuria occurs secondary to a genetic mutation of the FMO3 gene, located on chromosome 1q24.3. Various FMO3 mutations result in decreased enzyme activity, impaired substrate binding, or disrupted protein structure.
In patients with TMAU, excessive amounts of unmetabolized trimethylamine are exuded from the skin surface with sweat, causing a characteristic fish-like body odor, which can be noticed regardless of the patient's good personal hygiene. Scientists from the Monell Center report that approximately one third of patients with unexplained body malodor production test positive for the metabolic disorder trimethylaminuria (TMAU). A definitive diagnosis offers relief to these individuals, as symptoms of TMAU can hinder social and workplace interactions and cause psychological distress.
The composition of the skin microbiota varies from one individual to another and between locations on the same host. Antiperspirants have a significant effect on the microbiome. The diversity increases and an increase of the Actinobacteria phylum is seen, containing the odor-causing Corynebacterium species. If Corynebacterium spp. become more dominant, the subject's armpit body odor can increase and change to a more sour/musky odor.
Essentially, the foods that will impact body odor the most are those that are high in sulfuric acid. Spices like curry, cumin, and fenugreek can pack a punch when they attach to your tongue and teeth. Not only can these spices linger for hours on your breath, but they can also stick to your hair, skin, and clothes. These spices also contain volatile compounds that can be absorbed into your bloodstream and released through your sweat glands, leading to a distinct odor.
Garlic presents a nuanced picture. In a crossover study, 42 male odor donors were allocated to either a "garlic" or "non-garlic" condition, after which they wore axillary pads for 12 hours to collect body odor. One week later, the conditions were reversed. Odor samples were then judged for pleasantness, attractiveness, masculinity, and intensity by 82 women. No significant differences were found in ratings of any characteristics in study 1. However, the odor of donors after an increased garlic dosage was assessed as significantly more pleasant, attractive, and less intense (study 2) and more attractive and less intense in study 3. These results indicate that garlic consumption may have positive effects on perceived body odour hedonicity, perhaps due to its health effects (e.g., antioxidant properties, antimicrobial activity).
Research by Havlicek and Lenochova (2006) found that body odour of individuals on a non-meat diet was perceived as more pleasant, attractive, and less intense compared to the same individuals on a meat diet. This crossover study used sensory panel ratings of axillary pad samples. The findings are consistent with the hypothesis that fatty acid metabolites from meat digestion may be excreted through sweat, but the study population was limited and evidence is preliminary.
Dietary modifications to reduce the intake of TMA precursors are often recommended for TMAU. Foods rich in choline, carnitine, and TMAO should be limited or avoided. This may include reducing or eliminating the consumption of certain types of fish, red meats, liver, eggs, legumes, and specific vegetables.
Trimethylamine (TMA) is a volatile, aliphatic tertiary amine known for its characteristic odor of rotten fish. It is formed from excess choline and other TMA-containing dietary nutrients by gut bacteria.
Broccoli, cabbage, and Brussels sprouts are packed with nutrients, but they also contain sulfur. Like garlic and onions, these vegetables can lead to a more noticeable body odor when they break down in the body. This effect is due to the release of volatile sulfur-containing metabolites, including hydrogen sulfide and methanethiol, during digestion.
While not studied in high-quality controlled trials specifically for body odor, hydration is consistently discussed in authoritative nutritional sources in the context of sweat composition. Eccrine sweat is composed of 98–99% water, and adequate hydration is associated with more dilute sweat secretion. More concentrated sweat — as may occur during dehydration — could theoretically provide a more concentrated substrate for bacterial metabolism, though direct clinical evidence specifically linking dehydration to malodor intensity is limited.
Mechanistic context: Natsch et al. reported that odorous E3M2H, along with its hydrated analogue (R)/(S)-HMHA, are released from glutamine conjugates (present in axilla secretions) by a specific zinc-dependent N-α-acyl-glutamine aminoacylase (N-AGA) from commensal Corynebacterium species that reside on the skin of the axilla. This makes zinc relevant to the enzymatic machinery of odor production at the bacterial level. Suzuki et al. confirmed that zinc ions might be useful in inhibiting oral malodor caused by excess of gaseous hydrogen sulfide.
Traditional use: Zinc has not historically been used as a standalone remedy for body odor in traditional medicine systems. Its incorporation into hygiene and deodorant preparations reflects more modern nutritional and cosmetic science.
Scientific evidence: Small-scale studies and in vitro research have shown that magnesium salts can inhibit the proliferation of certain skin bacteria, such as Corynebacterium species, known contributors to malodor. However, large-scale, controlled clinical trials directly assessing magnesium's effectiveness versus placebo or other deodorant agents are limited, and most evidence comes from laboratory studies, anecdotal reports, or user testimonials. Evidence specifically for oral zinc supplementation reducing body odor in general populations is currently insufficient.
Traditional use: Historically, magnesium was not a traditional remedy for body odor, but its use in modern formulations is supported by the desire for less irritating and more natural alternatives to aluminum and baking soda.
Scientific evidence: Overall, while the mechanistic and preliminary clinical evidence is promising, the body of scientific validation remains modest. No large-scale, placebo-controlled trials confirm that oral or topical magnesium supplementation reduces body odor in healthy individuals.
Context in TMAU: Riboflavin is a cofactor for the FMO3 enzyme that is deficient in trimethylaminuria. In the management of TMAU, riboflavin supplementation has been explored as an adjunct to dietary restriction to support residual FMO3 enzyme activity. However, this application is specific to a genetic metabolic disorder, and the evidence base for riboflavin's effect on body odor in people without TMAU is negligible.
Traditional use: Sage (Salvia officinalis) has a long history of traditional use for reducing body odor. Historical texts and folk medicine practices, especially in Europe, have recommended sage as a remedy for excessive sweating (hyperhidrosis) and as a natural deodorant. The rationale behind this use is largely based on sage's astringent properties, attributed to its tannin content, which can constrict skin and reduce sweat production. Additionally, sage contains essential oils such as thujone and camphor, which have mild antimicrobial effects, potentially inhibiting the growth of odor-causing bacteria on the skin.
An early published account (1897) recorded in the PMC archive noted that infusion of sage was recommended for the treatment of hyperhidrosis in tuberculous subjects as well as those suffering from leukemia, rheumatic polyarthritis, and typhoid fever; in 38 cases where it was tried, there were only two failures.
Scientific evidence: Several small clinical trials and observational studies have reported that sage, administered as tea, liquid extract, or tablet, can significantly reduce abnormal sweating, such as that seen in hyperhidrosis or menopausal hot flashes. Sage (Salvia officinalis) has been traditionally used to manage excessive perspiration, particularly in Europe. In recent years, some scientific studies have investigated its efficacy for this condition. The main active constituents thought to be responsible for its anhidrotic (sweat-reducing) effects are thujone, rosmarinic acid, and various flavonoids.
A randomized controlled trial published in Advances in Therapy (2011) found that sage tablets reduced the frequency and severity of hot flashes and night sweats in menopausal women compared to placebo. The proposed mechanism involves sage's anticholinergic properties, which can inhibit stimulation of sweat glands.
However, direct evidence for sage's ability to reduce body odor rather than just sweating is sparse, and most clinical studies focus on hyperhidrosis rather than odor itself. Evidence strength: preliminary; limited to small trials; no definitive body-odor–specific clinical trials in healthy populations.
Traditional use: Chlorophyll as an "internal deodorant" was popularized in mid-twentieth century American medicine and consumer products. Chlorophyll (the pigment that makes plants green) has been marketed for decades as an internal deodorant. The theory: it neutralizes odors from the gut and bloodstream before they can cause bad breath.
Scientific evidence: There have been studies on chlorophyllin supplements to reduce the odor associated with urine and stool in elderly patients with catheters and ostomies, but these did not show a statistically significant improvement in smell. Research is limited and the evidence anecdotal about the value of chlorophyll supplements to address body odor.
A study found that chlorophyllin tablets were helpful in controlling body and fecal odors in a group of 62 elderly nursing home residents. It also aided in easing chronic constipation and abating excessive flatus. However, this was a small, older study with methodological limitations. Modern clinical reviews explicitly note there is no convincing modern evidence that oral chlorophyll improves general body odor or chronic bad breath. In the context of TMAU specifically, copper chlorophyllin has been discussed as a sequestering agent to reduce TMA production. Evidence strength: weak to negative for general body odor; small or uncontrolled studies only.
Traditional use: The deliberate application of probiotic organisms to the skin for odor management has no recognized traditional precedent. This is an entirely modern, evidence-driven investigation.
Scientific evidence: Applying topical probiotics can reduce malodor by outcompeting odor-producing bacteria. A study by Callewaert et al. transplanted axillary microbiota from non-odor producers to people with bromhidrosis, reducing their body odor.
A 2022 study published in Frontiers in Microbiology enrolled 10 patients with axillary osmidrosis (AO) — a clinical form of severe armpit body odor. One armpit received Lactobacillus bulgaricus mixed in saline for 28 days; the other received saline only as a control. The results were statistically significant: AO severity decreased significantly in the treatment arm (p = 0.013), and Corynebacterium abundance — the dominant odor-producing genus in the axilla — showed a corresponding significant decrease (p < 0.01) in the probiotic-treated armpit.
A study published in Scientific Reports (2021) tested the potential of a Lactobacillus acidophilus KNU-02-mediated bioconverted product of Lotus corniculatus seed to reduce axillary malodor. A chemical profile analysis revealed that benzoic acid was the most abundant chemical compound in the product, which increased following bioconversion. BLC treatment was found to reduce the intensity of axillary malodor.
Evidence strength: preliminary but mechanistically plausible. Topical probiotic approaches have the most direct evidence; oral probiotic effects on skin odor remain largely theoretical in human studies. Sample sizes in published trials are small. The field is rapidly evolving.
Traditional use: Activated charcoal has been used historically in various cultures for its adsorptive properties in gastrointestinal conditions. Its use as an internal deodorant is a more recent extension of this application.
Scientific evidence: Activated charcoal can be used as a supplement to reduce TMA production, but its effectiveness varies. Its proposed mechanism in the context of TMAU and body odor is adsorption of TMA within the gastrointestinal tract. Controlled clinical evidence in the general body-odor population is lacking. Evidence strength: very limited; use is principally described in the context of TMAU management.
Traditional use: Green tea (Camellia sinensis) has been used in traditional East Asian medicine and culture for a wide range of purposes, and its antimicrobial properties have been recognized in traditional practice.
Scientific evidence: Green tea polyphenols, including epigallocatechin gallate (EGCG), are recognized for antimicrobial activity in vitro against multiple bacterial species, including some associated with body odor. Plant-derived products are a cheap source of bioactive compounds that are common ingredients in cosmetics. However, no rigorous clinical trials specifically examining green tea supplementation or consumption for the reduction of body odor have been identified in the peer-reviewed literature. Evidence is currently in vitro or mechanistic only.
Malodor associated with accumulation of bacterial metabolites in body fluids might result from diet, which contains direct or indirect odorants (i.e., substrates for the production of odorants by bacteria). This gut-to-skin pathway is best documented in TMAU, where TMAU is caused by the inability of the person to break down a smelly chemical in the body called trimethylamine (TMA) into the non-odorous form trimethylamine oxide (TMAO). The TMA builds up in the body and is excreted via urine and sweat, producing the smell.
More broadly, body odor is a characteristic human trait that is generated by the bacterial degradation of odorless natural secretions into volatile odorous molecules. Therefore, malodor formation highly depends on the interplay between commensal bacteria with their catalytic enzymes and the unique sweat secretions of the human host.
Washing removes sweat and reduces bacterial numbers, helping to limit odour. Changing clothes after heavy sweating is also important, as fabrics can trap sweat and microbes. Regular bathing and clean clothing reduce the build-up of odour-causing compounds.
The main function of sweat is cooling. When body temperature rises during exercise, stress, or hot weather, sweat evaporates from the skin and carries heat away. Exercise increases total sweat output from both eccrine and apocrine glands, increasing substrate availability for skin bacteria. Regular exercise has not been shown in rigorous trials to either increase or decrease baseline body odor; the acute effect depends on hygiene practices post-exercise.
The growth of bacteria in the tissues of clothing is due to secretions of the apocrine sweat glands and products containing skin desquamation, existing natural particles in the fibers of the tissues, and sometimes the fibers themselves. Armpits and feet tend to smell more strongly because they combine dense sweat glands with warmth and moisture, creating favourable conditions for bacterial growth.
Axillary hair functions as a collecting site for apocrine secretions and increases the surface area available for bacterial proliferation, thereby increasing the opportunity for bacterial metabolism of odor precursors. This relationship has been noted in dermatological literature but has not been rigorously quantified in controlled nutritional intervention studies.
Activated charcoal has been studied as a dietary supplement and topical agent for body odor, particularly in trimethylaminuria (fish odor syndrome). A published study in Japanese TMAU patients found that oral activated charcoal decreased urinary trimethylamine excretion, reducing the source of fishy body odor. Evidence for general body odor reduction in healthy people is limited and largely anecdotal.
The same placebo-controlled RCT (n=80, 4 weeks) that established champignon extract's effect on halitosis simultaneously demonstrated significant improvement in body and fecal odor across all active-dose groups. Mechanistically, the extract suppresses intestinal generation of indole, tryptamine, p-cresol, and ammonia — precursors that are absorbed into blood and released through skin and breath. Effects were dose-dependent.
Chlorophyllin has clinical evidence for reducing body and fecal odor in specific medical populations. Human studies show benefit in colostomy and incontinence patients, and a controlled study in trimethylaminuria (fish odor syndrome) demonstrated normalization of urinary trimethylamine with 180 mg/day copper chlorophyllin over 3 weeks. Evidence for reducing general perspiration odor in healthy individuals is weak.
Chlorophyllin, a water-soluble derivative of chlorophyll, has documented clinical use as an internal deodorant. A study of Japanese TMAU patients found that oral copper chlorophyllin (60 mg three times daily) significantly reduced urinary trimethylamine levels over three weeks, reducing fish-like body odor. Earlier controlled studies in geriatric patients also showed reductions in urinary and fecal odor.
Garlic consumption produces body odor via allyl methyl sulfide (AMS), which is absorbed into blood, reaches the skin, and is excreted through sweat glands. This is a well-characterized, mechanistically understood phenomenon scientifically documented in human studies.
Magnesium, particularly as magnesium hydroxide, is used in natural deodorant formulations to control body odor by raising underarm skin pH, creating an inhospitable environment for odor-producing bacteria. A study in the Journal of Cosmetic Dermatology found magnesium hydroxide effective at reducing body odor without disrupting the skin microbiome. A clinical study with a magnesium-based formulation (CareMag® D) showed over 40% reduction in malodor with 84% of participants reporting long-lasting protection.
Tea tree oil (Melaleuca alternifolia) contains terpinen-4-ol and other antimicrobial compounds that are effective against body odor-causing bacteria including Staphylococcus epidermidis and Corynebacterium species. Multiple laboratory and clinical studies support its broad-spectrum antimicrobial activity. It is widely incorporated into commercial natural deodorant formulations and used topically in Australia for nearly 100 years for antiseptic purposes.
Sage (Salvia officinalis) has traditional use in European herbal medicine for excessive sweating (hyperhidrosis), which directly contributes to body odor, and is approved by German health authorities for treating hyperhidrosis. Several small clinical trials show that oral sage (as tea, liquid extract, or tablet) significantly reduces excessive sweating, particularly menopausal sweating. Topically, sage extracts have antimicrobial properties that may help reduce odor-causing bacteria on the skin.
Zinc, particularly as zinc oxide, has robust clinical evidence for reducing axillary body odor. A randomized, double-blind, placebo-controlled trial (ZINC-ON, presented at ECCMID 2019, published in Acta Dermato-Venereologica) in 30 healthy volunteers found that topical ZnO application for 13 days significantly reduced odor-producing Corynebacterium spp. and Staphylococcus hominis, and reduced self-perceived malodor compared to placebo. Zinc salts have also been used in deodorant formulations for their odor-neutralizing and mild antimicrobial properties.
Geranium EO is used as a natural deodorant ingredient, with antimicrobial activity against odor-causing bacteria and a pleasant floral fragrance. Herbal medicine sources document its use as an insect repellent and deodorant. No clinical deodorant efficacy trials have been conducted.
Witch hazel (Hamamelis virginiana) has a long traditional use as an astringent and antimicrobial agent in skin care, including as a natural deodorant ingredient. Its tannins, proanthocyanidins, and gallic acid provide antibacterial and astringent properties that reduce skin-surface bacteria and tighten pores, limiting the environment in which odor-causing microbes thrive. While widely used in natural deodorant formulations, rigorous clinical trials specifically for body odor are limited.
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