Older adults are at a decreased risk for iron deficiency with the exception of a few conditions, most notably blood loss.

Older adults may be at risk of vitamin A overdose.

Like other body systems, the nails (fingernails, toenails) are a tissue that can manifest complications of diabetes.

A scientific review of Zinc in deficiency and excess.

The Savage Nutritionists details how vitamin B12 deficiency leads to loss of vibratory sense and how a practitioner may diagnose it.