Question

which products do not have scientific studies supporting their claims to be beneficial when used?
cofactors and coenzymes to support enzyme function
lactase enzymes used in milk sugar digestion
enzymes that aid in the digestion of oligosaccharides
enzymes to promote immune system function

Explanation:

Cofactors, coenzymes, lactase enzymes for milk - sugar digestion, and enzymes for oligosaccharide digestion have well - established scientific bases. However, there is currently less scientific evidence to strongly support the claim that enzymes can directly promote immune system function.

Answer:

Enzymes to promote immune system function