Magnesium, calcium, potassium, fiber, vitamin C, D, and E. Potassium is a good example, as supplementation is impossible, supplements are limited to 99mg by law. Vitamin E supplements have shown harm in clinical trials.

The vast majority of Americans are chronically deficient in vitamin D, for example.

And many "Walmart-quality" supplements are so badly made that you gain no measurable benefit by taking them.