GLOSSARY

Conditionally Essential Nutrient is a substance usually made by the body whose synthesis may become insufficient in particular life stages or disease states. The classification depends on the person's circumstances and should not be confused with a substance being essential for everyone at all times.

During some growth stages or severe illnesses, internal synthesis may fail to meet demand despite being adequate in health. This must be defined for the particular compound and condition. One hard workout alone does not make every compound conditionally essential or justify supplementation.

Nutritional essentiality concerns the body's synthetic capacity: a substance must be supplied by the diet because production is absent or insufficient. This differs from general usefulness or a supplement's popularity and does not by itself specify the required amount.

The body can make some compounds from other precursors. Synthesis requires energy, starting materials, and enzyme activity, so it does not mean independence from food. One example is hepatic glucose production from non-carbohydrate precursors under appropriate conditions.