Generally improper digestion causes body odor, but some vegetables like beetroot also can make a person smell like fish. Beetroot like spinach is rich in methyl compounds and releases tri-methylamine as a waste product. This is excreted from the human body through sweat and perspiration. The smell gets accentuated by the bacteria that feed on such chemicals like tri-methylamine in the human sweat.The result is the body gives out a fishy reek and stench. It actually takes the bacteria a couple of minutes to turn this into its own waste products, such asisovaleric acids and androstenes, which are actually very smelly.