Punctuation Correction: Proper Comma Usage in Sentences

The original sentence—"Beriberi is rare in the West as nowadays the average diet is good"—lacks a necessary comma before the dependent clause.

Corrected Version

"Beriberi is rare in the West, as nowadays the average diet is good."

Rule

Use a comma before a subordinate clause (starting with as, because, since) when it follows the main clause and expresses a distinct reason. This improves readability and clarifies the causal relationship.

Additional Examples

• Incorrect: "He left early because he was tired."
• Correct: "He left early, because he was tired." (Optional but preferred for clarity)
• Incorrect: "She stayed home since it was raining."
• Correct: "She stayed home, since it was raining."

Note: In modern usage, the comma before because clauses is often omitted if the clause is essential to meaning, but with as and since indicating reason, a comma is standard.