A change in body odor, especially one that takes on an unexpected sweet or syrupy scent, can be startling. While sweat itself is primarily odorless, an individual’s scent is determined by the unique mix of compounds excreted by the body and metabolized by bacteria on the skin. This distinct maple syrup-like smell suggests that certain metabolic byproducts are being released through the skin, indicating a shift in internal biochemistry. This phenomenon points toward a few distinct biological or dietary causes.
The Rare Genetic Condition
The description of a maple syrup odor is most closely associated with a rare, inherited metabolic disorder known as Maple Syrup Urine Disease (MSUD). This condition results from the body’s inability to properly break down three specific branched-chain amino acids (BCAAs): leucine, isoleucine, and valine. The deficiency lies in the branched-chain alpha-keto acid dehydrogenase (BCKAD) enzyme complex, which is necessary for BCAA metabolism.
When BCAAs are not processed correctly, they and their corresponding keto acid derivatives accumulate in the blood and bodily fluids, including sweat and urine. This buildup leads to a distinctive sweet, burnt sugar, or maple syrup-like odor. While MSUD is typically detected during newborn screening, less severe forms may not present until later in childhood or adulthood, often triggered by stress or illness. These later-onset forms can still cause symptoms like vomiting, weight loss, or changes in alertness during a metabolic crisis.
Ketones and Blood Sugar Fluctuations
A more common cause for a sweet or fruity body odor in adults involves the production of ketones, which are metabolic byproducts of fat breakdown. When the body cannot utilize glucose for energy, it breaks down fat, generating ketones, including acetone. Acetone is a volatile compound partially exhaled through the breath and excreted through the sweat, giving off a characteristic fruity or nail polish remover-like scent.
This metabolic state of ketosis can occur under two primary circumstances. The first is Diabetic Ketoacidosis (DKA), a medical emergency most often seen in people with Type 1 diabetes. DKA occurs when insufficient insulin prevents glucose from entering cells, causing blood sugar levels to rise dangerously high while the body burns fat for fuel, leading to a toxic buildup of ketones. The second is intentional nutritional ketosis, achieved by following a very low-carbohydrate diet, such as the ketogenic diet. This dietary change forces the body to switch its primary fuel source from glucose to fat, resulting in a milder, expected sweet-smelling side effect as acetone is expelled.
Dietary Triggers and Supplementation
Sometimes, a sweet odor is neither a genetic disorder nor a sign of ketosis, but rather the temporary result of ingesting certain compounds. The most notable dietary cause for a true maple syrup scent is the herb fenugreek, a common ingredient in Indian and Middle Eastern cuisine. Fenugreek contains a potent aromatic molecule called sotolon, which is also a major flavor component in artificial maple syrup.
When fenugreek is consumed, the body may absorb and excrete sotolon through sweat and urine without fully metabolizing it. This process can impart a distinct maple syrup-like smell to the body’s secretions, a phenomenon sometimes referred to as “pseudo-maple syrup urine disease.” Certain supplements can also alter body odor; for instance, high doses of some B vitamins can produce stronger, more pungent scents as they are excreted.
Next Steps and Medical Consultation
Any sudden, unexplained change in body odor warrants a conversation with a healthcare professional to rule out serious underlying conditions. If the sweet or fruity smell is accompanied by concerning symptoms, such as extreme fatigue, confusion, excessive thirst, frequent urination, nausea, or rapid weight loss, immediate medical attention is necessary. These signs can indicate DKA, a life-threatening condition requiring urgent treatment with insulin and intravenous fluids.
A doctor can determine the cause of the odor by reviewing your diet and performing diagnostic tests. Simple blood or urine tests can measure blood sugar levels and the concentration of ketones, helping to distinguish between nutritional ketosis, DKA, or other metabolic issues. If a metabolic disorder is suspected, specialized tests can identify the presence and concentration of branched-chain amino acids. Tracking the onset of the smell and noting any recent dietary changes or new supplements will provide valuable information for an accurate diagnosis.