Selenocysteine is recognized as the 21st amino acid and is an essential component of several selenoproteins, which play crucial roles in antioxidant defense and redox regulation. The pancreas, particularly the head of the pancreas, is rich in these selenoproteins—most notably glutathione peroxidases and thioredoxin reductases. These enzymes are vital for protecting pancreatic tissue from oxidative damage, especially given the high metabolic activity and exposure to reactive oxygen species in this organ.

Scientific studies have demonstrated that selenium deficiency (and consequently, diminished selenocysteine incorporation into selenoproteins) can impair pancreatic function and increase susceptibility to pancreatic tissue damage. Some research has linked low selenium status with increased risk for pancreatic disorders, including pancreatitis and even pancreatic cancer. However, most evidence relates to general pancreatic health or oxidative stress, rather than targeted effects on the "pancreas head" specifically.

While there is a plausible biochemical rationale and supporting animal and human data for the importance of selenocysteine-containing proteins in pancreatic health and function, direct clinical trials using selenocysteine supplements for pancreatic diseases are limited. The evidence justifies a moderate rating, and the use is grounded in scientific understanding of biochemistry and physiology rather than tradition.