What are the nutrients that can not be synthesized by human cells?

Humans cannot synthesize certain essential nutrients, which must be obtained through diet. These include essential amino acids (like lysine and tryptophan), essential fatty acids (such as omega-3 and omega-6 fatty acids), vitamins (like vitamin C and most B vitamins), and certain minerals (such as calcium and iron). Without these nutrients, the body cannot perform vital functions, leading to deficiencies and health issues.