A deficiency of riboflavin can be primary - poor vitamin sources in one's daily diet - or secondary, which may be a result of conditions that affect absorption in the intestine, the body not being able to use the vitamin, or an increase in the excretion of the vitamin from the body.
Substantial evidence means more than a mere scintilla. It means such relevant evidence as a reasonable mind might accept as adequate to support a conclusion.. Richardson v. Perales, 402 U.S. 389, 401 (1971).
Something substantial is large in size, number, or amount: If you want to say someone spent a lot of money without being too specific, you could say they spent a substantial amount of money. The adjective substantial derives from the Latin substantia substance, which means stuff. A substantial meal is large enough to satisfy hunger. A substantial structure is strongly made or built. And a substantial man possesses wealth and property. Related to this last sense, a man of substance refers to a wealthy man with property.