I am an 18 year old male with a diastolic blood pressure reading 53. what is my medical condition and would i be able to drink alcohol in moderation?

Congratulations!: That's an exceptional diastolic bp. I hope the rest of you is as healthy. Without knowing the rest of your history, the second part of your question is not easily answerable.

Probably normal.: Generally, BP is in 110/70 range in young healthy people - recheck pressures on different machines and at doctor's office also if low - they need to listen to your heart if persisently low. 1 or 2 small alcoholic drinks a day may be consumed by men (only one for women ...Sorry). Do not start drinking for 'heart health' - instead eat more red grapes, avoid obesity and exercise regularly.