Eggs, Fish, Meat and Cheese Are All This Nutrient
Puzzle 7 of Running a Marathon Pack
Question is: Eggs, Fish, Meat and Cheese Are All This Nutrient
and the answer is: PROTEIN
Word Meaning:
PROTEIN — (biochemistry, countable) Any of numerous large, complex naturally-produced molecules composed of one or more long chains of amino acids, in which the amino acid groups are held together by peptide bonds.
Definitions from Wiktionary.