Does elbows in gas pipe affect flow?

Hi, I have 10 elbows in my gas pipe from the gas meter to the boiler. A plumber has told me that this will reduce the flow of gas going into the boiler and so it will not be enough flow to fit a combi boiler and the max I can fit is an 18kw boiler. Please can you confirm if that is correct? Other plumbers have not mentioned the gas flow as an issue.