Carlos Solis
Most people know that body odor comes from sweat. But sweat isn’t all the same. The strongest smells appear when bacteria on the skin break down secretions from apocrine glands, which concentrate mainly in the armpits and groin.
Apocrine glands release a thicker, protein-rich fluid that is nearly odorless by itself. When skin bacteria break down that fluid, the familiar sharp armpit smell appears.
Another gland type, eccrine glands, are found across most of the body and secrete mostly water and salt. This kind of sweat usually has little smell, though heavy bacterial growth can make it contribute to body odor.
When odor signals a health problem
Small changes in body smell can sometimes point to serious medical issues. People with poorly controlled diabetes may develop a sweet, fruity scent on their breath or skin that others compare to pear candy or nail polish remover.
This scent can signal diabetic ketoacidosis, a medical emergency that occurs when a lack of insulin allows ketones to build up in the blood.
Liver disease often brings a musty or fecal-like odor, and kidney failure can make the body smell of ammonia because the kidneys struggle to clear metabolic wastes.
Infections alter odor, and hormonal shifts during pregnancy, the menstrual cycle, or menopause can change how someone smells.
Researchers are testing whether a person’s scent could help diagnose disease earlier and more accurately. For example, studies into Parkinson’s disease found that the mix of volatile organic compounds on the skin can shift long before clear neurological symptoms appear. One clue came from a woman who noticed an unusual musky smell from her husband years before he received a diagnosis.
How diet, lifestyle, and your skin microbiome affect smell
A stronger or unusual odor doesn’t always mean disease. Spices and foods like garlic, onion, or curry contain volatile compounds that release through sweat. Alcohol, caffeine, and some medications can also change your body’s scent.
Nervous-system activity alters sweat composition, so stress can change how you smell. Your individual skin microbiome—the community of bacteria living on your skin—plays a major role; those microbes determine why some people smell stronger than others.
What to do if an odor bothers you
- Keep good personal hygiene. Wash regularly with soap, focusing on areas with apocrine glands to reduce the bacteria that break down secretions.
- Use antiperspirants to reduce sweat production and deodorants to mask odor.
- Wear clothing made of natural or moisture-wicking fabrics, such as cotton or performance materials, to limit bacterial growth during activity.
- Stay hydrated and eat a balanced diet to help reduce strong or specific smells.
- See a doctor if odor changes persist, come from an unknown source, or appear with other symptoms—especially if you have diabetes, liver disease, or kidney problems.
Body odor rarely pins down a diagnosis on its own, but it can offer a useful clue. Paying attention to changes in your scent helps you catch signals from your body that might otherwise go unnoticed.
Based on material from BBC Science Focus
