Why GNC slumped during the vitamin supplement boom

For decades, GNC was the place to shop for vitamins, protein powder, and practically any kind of weight-loss supplement. If you ever needed a health boost, chances were there was a GNC at a mall nearby. But the once strong supplement store has grown frail during a time when the dietary supplement industry is seeing huge growth. So after 85 years in business, why wasn't GNC been able to capitalize on the latest dietary supplement boom, and what led to the company's bankruptcy filing?