I have a dataframe that I am putting into a sweave document using xtable, however one of my column names is quite long, and I would like to break it over two lines to save space

calqc_table<-structure(list(RUNID = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L), ANALYTEINDEX = c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L), ID = structure(1:11, .Label = c("Cal A", "Cal B", "Cal C", 
"Cal D", "Cal E", "Cal F", "Cal G", "Cal H", "Cal High", "Cal Low", 
"Cal Mid"), class = "factor"), mean_conc = c(200.619459644855, 
158.264703128903, 102.469121407733, 50.3551544728544, 9.88296440865076, 
4.41727762501703, 2.53494715706024, 1.00602831741361, 199.065054555735, 
2.48063347296935, 50.1499780776199), sd_conc = c(2.3275711264554, 
NA, NA, NA, NA, NA, NA, 0.101636943231162, 0, 0, 0), nrow = c(3, 
1, 1, 1, 1, 1, 1, 3, 2, 2, 2)), .Names = c("Identifier of the Run within the Study", "ANALYTEINDEX", 
"ID", "mean_conc", "sd_conc", "nrow"), row.names = c(NA, -11L
), class = "data.frame")
calqc_xtable<-xtable(calqc_table)

I have tried putting a newline into the name, but this didn't seem to work

names(calqc_table)[1]<-"Identifier of the \nRun within the Study"

Is there a way to do this ? I have seen someone suggest using the latex function from the hmisc package to manually iterate over the table and write it out in latex manually, including the newline, but this seems like a bit of a faf !