What is an optimal AST level?
The short answer
An optimal AST level is under 30 U/L. That is Dr. Peter Attia's number. You can watch him say it below.
Most labs call AST high only above 40. So your report can call 35 normal while it sits above where he draws the line.
“now the general rule of thumb is that you would like to see an A and ALT both below about 30 IU per liter”
Where a number lands, and who said so
- under 30 U/L The range Dr. Peter Attia draws
- 30–40 U/L Normal on most reports. Above optimal Dr. Peter Attia · 17:32 →
- over 40 U/L Most labs flag this as high
What AST measures
An enzyme found in your liver, but also in muscle and heart tissue.
Paired with ALT, it separates liver strain from muscle damage. Hard exercise alone can raise it.
Checked against MedlinePlus — AST Test.
One of the doctors we cite, on why it matters
“these are enzymes made by the pyes that are released into plasma when the liver is stressed so as you see more alt and a that indicates more stress”
Common questions
What is an optimal AST level?
Under 30 U/L, according to Dr. Peter Attia.
What is a normal AST level?
Most US labs print 0–40 U/L. Your report grades you against that range. It exists to catch disease, not to describe your best.
What does your AST number mean?
Under 0 U/L, your report marks it low. Between 0 and 40 it prints as normal. Over 40, your report marks it high. Where the people we follow draw their own line is above.
Is AST of 35 normal?
Your lab will call it normal. Dr. Peter Attia puts the ceiling at 30 U/L, so by that number it is high.
What does the AST test measure?
An enzyme found in your liver, but also in muscle and heart tissue. Paired with ALT, it separates liver strain from muscle damage. Hard exercise alone can raise it.
Where does this number come from?
Dr. Peter Attia, on video. The link above jumps straight to that minute.