It's an NAD. Since the first letter of the abbreviation NAD (Nicotinamide Adenine Dinucleotide) begins with a vowel sound, we use the article an (not a).

It's an NAD. Since the first letter of the abbreviation NAD (Nicotinamide Adenine Dinucleotide) begins with a vowel sound, we use the article an (not a).

An NAD booster can help slow the aging process.

A NAD booster can help slow the aging process.

Remember, the rule for choosing between a and an is based on the initial sound of the following word, and not how it's spelled.

It can be considered an NAD bacterial enzyme involved in amino acid metabolism.

And we say an N (not a N).

Her new T-shirt has an N on it.

A partial list of abbreviations that begin with N and take "an" can be found below:

• an NBA (National Basketball Association)
• an NDA (Non-Disclosure Agreement)
• an NFL (National Football League)
• an NFT (Non-Fungible Token)
• an NGO (Non-Governmental Organization)
• an NLP (Natural Language Processing)
• an NMN (Nicotinamide Mononucleotide)
• an NRA (National Rifle Association)
• an NSA (U.S. National Security Agency)
• an NYSE (New York Stock Exchange)