The makers of Vegemite have never officially disclosed the ingredient list to the public. One of the likely ingredients is Brewer's yeast. Vegemite was invented by a young chemist named Dr. Cyril P Callister. He was hired by the Fred Walker Company in 1922 to create a spread from Brewer's yeast. Other ingredients in Vegemite are malt extract derived from barley and yeast extract, from yeast grown on barley and wheat.
The official recipe is a secret, but Vegemite's website does reveal that the ingredients of Vegemite have not changed since its introduction in 1923. They also state Vegemite contains B vitamins and contains practically no fat.
Vegemite is a spread primarily consumed in Australia, where it's found in the pantries of approximately 80 percent of households. About 22 million jars of Vegemite are manufactured each year in Australia and 1.2 billion servings of the spread are consumed by Australians.
Fred Walker's daughter came up with the name Vegemite, which was chosen out of hundreds of entries in a national competition to name the product. Vegemite has been produced in Australia since its launch in 1923. 90 percent of the ingredients are sourced from within Australia and only 2 percent of Vegemite is exported overseas. Vegemite is certified Halal and kosher and does not contain genetically modified organisms. https://www.reference.com/food/ingredients-vegemite-bec0d1b07a0ec220