Oh, you've heard:

the same nutrients we need to maintain our day-to-day health – such as vitamin D, omega-3 fatty acids, and magnesium – are also critical components of enzymes required for our bodies’ long-term maintenance, in roles such as DNA repair, cardiovascular health and prevention of oxidative damage.

Or:

As a consequence, Ames writes, when the body is faced with shortages of key nutrients, it must “ration” them, enabling enzymes critical to our immediate survival and reproductive capacity to keep functioning at the expense of longer-term physiological needs.

Or:

such trade-offs can be seen in people with chronic, low-level deficiencies in Vitamin K and the element selenium (which are key components of 16 and 25 different enzymes, respectively).

Or maybe just that long-term vitamin and mineral deficiencies have observable effects?