There are many supplements available today that do not fit into the
category of vitamin or mineral or herb.
Amino Sugars like glucosamine and phospholipids such as
phosphatidylserine are considered nutrients, even though they are not
technically vitamins.
Essential Fatty Acids providing Omega-3 (alpha-linolenic) and Omega-6
(linoleic) acids must be obtained from food or supplements. Sources such
as Flax seed oil, Evening Primrose oil, and various fish oils also fall
into this category of supplements.