GLOSSARY

Beta-Cryptoxanthin is an oxygen-containing provitamin A carotenoid in fruits such as mandarins and papaya, distinct from beta-carotene.

Carotenoid is a pigment-family name, not a guarantee of provitamin A activity: lutein and lycopene should not be counted as retinol. Beta-carotene, alpha-carotene and beta-cryptoxanthin can contribute, with differing activity per mass. Varied fruit and vegetable colours diversify compounds, not identical vitamin doses from every colour or member.

Retinol activity equivalents compare vitamin A activity rather than simply adding pigment masses. Under the common convention, 1 microgram retinol corresponds to 12 micrograms dietary beta-carotene or 24 micrograms dietary alpha-carotene or beta-cryptoxanthin. These factors depend on form and source; supplemental beta-carotene uses a different factor, so the label's basis must be identified.

Liver and some animal or fortified foods provide preformed vitamin A; dark-green and orange vegetables can provide precursors. Contributions vary with food and portion. For athletes, varied sources are more useful than frequent liver consumption or stacking retinol products. Accompanying energy and fat also belong in the actual meal plan rather than being ignored because a vitamin is present.