Did Zach Bush get the chemistry of high-fructose corn syrup wrong?

Dr. Zach Bush claimed during his appearance on the Joe Rogan Experience that high-fructose corn syrup is a chemically flipped, mirror-image molecule that the human body cannot recognize. This claim is chemically incorrect.

In organic chemistry, some molecules have mirror-image versions called enantiomers, which are labeled as D-isomers or L-isomers. Fructose and glucose are chiral molecules. The naturally occurring, biologically active forms used by plants and animals are D-fructose and D-glucose. High-fructose corn syrup consists of these exact same natural D-isomers. There are no L-isomers or synthetic mirror-image sugars in the syrup.

The manufacturing process for the syrup relies on enzymes rather than synthetic chemical synthesis. Corn starch is first broken down into free glucose. Producers then introduce glucose isomerase, an enzyme that converts a portion of that glucose into fructose. This is the same biological transformation that occurs naturally inside ripening fruit. The resulting mixture is typically 42 percent or 55 percent fructose, with the remainder being glucose and water.

Metabolically, your body processes the fructose in high-fructose corn syrup exactly the same way it processes the fructose in a honey jar or an apple. Once absorbed, both sugars travel directly to the liver.

The real health danger of high-fructose corn syrup is the volume and speed of delivery, not its molecular structure. Highly refined liquid sugars enter the digestive system with zero fiber or structural food matrix to slow them down. This fast absorption floods the liver. Because the liver is the primary organ capable of metabolizing fructose, an excessive, sudden load forces the liver to convert the surplus sugar directly into fat. This pathway leads to non-alcoholic fatty liver disease, insulin resistance, and systemic metabolic stress.