Consuming asparagus can significantly and characteristically alter the smell of urine.

noli's read

This phenomenon is well-documented and is based on the presence of asparagusic acid in asparagus. During digestion, this compound is broken down into various volatile sulfur derivatives that are subsequently excreted in urine, causing this particular odor. A genetic study published in the BMJ (observational study) confirmed that this ability to produce and detect this odor varies among individuals due to genetic polymorphisms. It is therefore true that the smell changes, but the experience is unique to each person: not everyone produces these compounds in detectable quantities, and not everyone has the olfactory sensitivity to perceive them. The claim is therefore biologically grounded, although the 'significant' aspect depends greatly on the consumer's genetics.

the sources

No named source held this one up — that absence is part of the verdict.