A composition of an effective amount of (a) .gamma.-linolenic acid and/or dihomo-.gamma.-linolenic acid, optionally in association with linoleic and if desired other fat acids, said acids being used if desired as physiologically functional derivatives thereof, in conjunction with (b) an effective amount of one or more of natural or synthetic carotenoids or retinoids having, or giving rise in the body to compounds having, Vitamin A activity when used in therapy of a condition in which enhancement of 1-series PG production, or more broadly influence of the 1-series/2-series PG balance in the body in favor of 1-series PGs is required.