From the Guidelines
A sweet, maple syrup-like body odor is most likely caused by a rare genetic disorder called maple syrup urine disease (MSUD), which is characterized by the inability to break down certain amino acids, resulting in a distinctive sweet smell similar to maple syrup in sweat, urine, and ear wax. This condition is a type of organic acidemia, a group of disorders that lead to the accumulation of toxic compounds in the body, as discussed in the 2014 practice guideline by the American Association for the Study of Liver Diseases 1. The 2018 update on laboratory analysis of organic acids by the American College of Medical Genetics and Genomics also highlights MSUD as a disorder that can be identified through urine organic acid analysis, which can aid in diagnosis 2.
The underlying mechanism of MSUD involves a deficiency in the branched-chain keto acid dehydrogenase (BCKDH) complex, leading to the accumulation of leucine, isoleucine, and valine in the blood and bodily fluids. This accumulation produces a distinctive sweet smell similar to maple syrup, which can be detected in various bodily secretions. If left untreated, MSUD can lead to serious health complications, including neurological deterioration and impaired health-related quality of life.
Other potential causes of sweet-smelling body odor include:
- Uncontrolled diabetes, which can cause a fruity acetone smell
- Certain medications
- Specific foods in the diet
- Hormonal changes However, these causes are less likely to produce a sweet, maple syrup-like odor compared to MSUD.
It is essential to seek medical attention promptly if a sweet, maple syrup-like body odor is detected, as early diagnosis and treatment can significantly improve outcomes and quality of life. Treatment for MSUD typically involves a specialized diet low in the specific amino acids that the body cannot break down, and in some cases, medication or supplements may be necessary. In severe cases, liver transplantation may be considered to help manage the condition, as discussed in the 2014 practice guideline 1.
From the Research
Causes of Sweet Body Odor
- Maple syrup urine disease (MSUD) is a rare inborn error of metabolism that can cause a sweet, maple syrup-like odor in the urine and cerumen of affected individuals 3, 4, 5, 6.
- This disease is caused by defects in the branched-chain α-ketoacid dehydrogenase complex, leading to elevations of branched-chain amino acids (BCAAs) in plasma and α-ketoacids in urine 3.
- The classic presentation of MSUD occurs in the neonatal period and can lead to irreversible neurological complications if left untreated 3.
- Intermittent MSUD, a non-classic variant of the disease, can also cause metabolic crises with life-threatening neurological sequelae 5.
- In some cases, body odor may smell sweet due to the accumulation of BCAAs, such as leucine, isoleucine, and valine, which are not properly metabolized in individuals with MSUD 7.
Relationship Between MSUD and Sweet Body Odor
- The sweet, maple syrup-like odor is a characteristic feature of MSUD, and is caused by the accumulation of BCAAs and their metabolites in the body 3, 4, 5, 6.
- This odor can be detected in the urine, cerumen, and other bodily secretions of affected individuals 3.
- The intensity and frequency of the odor can vary depending on the severity of the disease and the effectiveness of treatment 4, 6.
Other Factors That May Contribute to Sweet Body Odor
- Poor oral intake and increased time spent in the fasting state can contribute to increased leucine levels and metabolic decompensation in individuals with MSUD 7.
- Infection and catabolism can also cause metabolic crises in individuals with MSUD, leading to the accumulation of BCAAs and their metabolites 5, 7.