What is the fate of the NAD newly regenerated by fermentation?

The NAD+ regenerated by fermentation is essential for maintaining glycolysis under anaerobic conditions. During fermentation, NADH produced in glycolysis is oxidized back to NAD+ as pyruvate is converted into byproducts like lactic acid or ethanol. This recycling of NAD+ allows glycolysis to continue producing ATP, which is vital for cellular energy, even in the absence of oxygen. Ultimately, the fate of regenerated NAD+ is to sustain metabolic processes that rely on anaerobic ATP production.