This is the 9171st most frequent Korean word.
건강기능식품이다
"Health functional food."
The word '건강기능식품이다' is used to describe the nature of the product as a health-enhancing consumable.
이 제품은 건강기능식품이다.
This product is a health functional food.
The term '건강기능식품이다' here highlights the reason for the product's effectiveness.
건강기능식품이다 보니 효능이 좋다.
Since it is a health functional food, its efficacy is good.
'건강기능식품이다' in this sentence signifies the type of food aimed at improving health that is being chosen.