Possible Clues:

• Vitamin in lean meat
• Cain in trouble for providing source of vitamin B
• Compound NI bill accepted
• Vitamin in wheat germ
• B3, nutritionally
• Third person tipped trendy vitamin
• Form of vitamin B3
• B3
• Vitamin of the B complex found in wheat, meat and dairy products
• An essential B vitamin in Cain, strangely