Do Brussel Sprouts Cause Urine to Smell?

Brussels sprouts are a highly nutritious food included in the Brassica genus of vegetables. They contain vitamin A, folate, fiber, beta-carotene and a high concentration of vitamin C. Brussels sprouts and other vegetables of the Brassica genus, such as asparagus and cabbage, also contain a special chemical called methyl-mercaptan. This chemical produces a bitter smell in the urine.

About Methyl-Mercaptan

Methyl-mercaptan is a colorless gas released from the feces of animals. It is a natural chemical found in the blood, brain and tissue matter of humans and animals alike. The gas is also released from animal decay in swamp areas and can be found in several types of natural gases, coal, tar and various crude oils. It is used in manufacturing to produce pesticides, plastics and even chicken feed.

Chemical Reaction of Methyl-Mercaptan

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Not a lot is known about the chemical reactions that occur in the body when consuming methyl-mercaptan. Scientists have researched the natural chemical for a number of years, and have reached a few conclusions. For example, we know that methyl-mercaptan leaves the body quickly after digestion. Studies in lab rats at the Agency for Toxic Substances and Disease Registry in the 1990s have indicated that once the chemical enters the blood stream, it is difficult to break down in the body and is either exhaled from the lungs as you breathe, or passes through the urine within a few hours 1. The toxin from the escaping methyl-mercaptan is the odor you smell when you urinate.

What Happens When You Eat Brussel Sprouts

During the consumption of Brussels sprouts, glucosinolates, which are nutrients that aid the body's detoxification system, break down into sulforaphane, which triggers natural enzymes in the liver to help eliminate toxins from the body. Scientists also believe that these glucosinolates interact with glutathione, a natural antioxidant found in the cells of all known life. It is this antioxidant that is thought to prevent cancer. Because sulforaphane is an organic compound that contains sulfur, it could also explain why scientists at the Agency for Toxic Substances and Disease Registry have detected amounts of sulfur in both the urine and breath of lab rats when given a dose of methyl-mercaptan 1. However, even though organosulfur compounds are often associated with a foul odor, it is unclear if the sulfur content of the urine caused the smell.

Healthy Despite the Odor

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A healthy diet that includes vegetables from the Brassica genus is desirable, and the advantages of overall better health with an improvement in body detoxification and a possible solution to fighting some of the most damaging cancers clearly outweighs a little embarrassment and some disconcerting odors. A good dietary choice is to eat these vegetables raw or cooked a few times a month. A study from the Roswell Park Cancer Institute recently proved that three servings of raw cruciferous vegetables per month protected against bladder cancer 3.