How do animals obtain sulfur from food?

Animals obtain the sulfur necessary for their biological functions primarily through the consumption of protein-rich foods. Sulfur is a vital component of specific amino acids, most notably cysteine and methionine, which are essential building blocks for proteins in all living organisms.123

When animals ingest protein, their digestive systems break these complex molecules down into their constituent amino acids, which are then absorbed into the bloodstream for use in growth, maintenance, and the synthesis of various enzymes, vitamins, and hormones. While plants can synthesize these sulfur-containing amino acids from inorganic sources like sulfate, animals generally lack this ability and must rely on their diet to provide them.1245

In the case of ruminant animals, microorganisms living in the rumen can synthesize amino acids, providing the host with a source of microbial protein that contains these necessary sulfur-bearing compounds.1