Perhaps you should try some spelling variations:
"cost of _ healthy adult" » "cost of _ healthy adults", "cost of _ healthy diet", "cost of _ health adult"
"cost of _ healthy dies" » "cost of _ healthy diets", "cost of _ healthy diet", "cost of _ healthy ties", "cost of _ health dies"

You may be able to get more results by adjusting your search query.

• The words AND, OR and NOT may confuse the search; try adding quotes: "((\"cost of _ healthy dies\") OR (\"cost of _ healthy adult\"))".
• Removing quotes may allow a broader search: (( cost of _ healthy dies ) OR ( cost of _ healthy adult )).
• Adding a wildcard symbol may retrieve word variants: (("cost of _ healthy dies") OR ("cost of _ healthy adult"))*.