functional food
n. Food that has been enhanced with vitamins or pharmaceuticals to provide specific health benefits.
Other functional food products include higher-calcium yogurt, calcium-added ice cream, anti-oxidant enriched eggs, soy products and nutritionally enhanced sweets.
—Megan Davis, “Convenience, conviviality mark mealtime trends for future,” Milwaukee Journal Sentinel, January 02, 2000
Concerned about cholesterol? McNeil Consumer Healthcare, a division of Johnson & Johnson, recently introduced a margarine that contains an ingredient shown to lower it by about 10 percent with two weeks of use.

Worried about bacteria that can upset your digestive system? Snap up a "digestive biscuit" or hot chocolate drink that Novartis plans to introduce in the United States sometime next year….

After some initial stumbles, the world's largest drug and consumer-goods companies are back with plans to introduce a growing number of these products, known as functional foods.
—David J. Morrow, “ A Medicine Chest or a GroceryShelf?,” The New York Times, December 12, 1999
1988 (earliest)
Medical foods do not technically exist in Japan because the Ministry of Health and Welfare does not recognize them and bans advertising that claims special therapeutic effects.

That is about to change, a ministry official said.

"The possibility of the categories and standards being fixed for functional foods next year is high, but at the moment there are no details," an official supervising the drafting of guidelines said.
—“'Medical' food boom predicted in Japan,” The Toronto Star, October 20, 1988