Marmite is a food spread made from yeast extract invented by German scientist Justus von Liebig and originally made in the United Kingdom. It is a by-product of beer brewing and is produced by Dutch-British company Unilever. Marmite is a dark brown, yeasty spread that is popular in the United Kingdom. If you're looking for a low-calorie spread for toast or crackers, you might want to give it a try. Marmite helps boost your intake of important vitamins and minerals and provides other health benefits.