I have a code chunk in an R Markdown file.

```{r}
library(UsingR)
```

Using knitHTML to compile causes the following output, which never happened before I updated to the latest versions of R and RStudio:

## Loading required package: MASS
## Loading required package: HistData
## Loading required package: Hmisc
## Loading required package: grid
## Loading required package: lattice
## Loading required package: survival
## Loading required package: splines
## Loading required package: Formula
## 
## Attaching package: 'Hmisc'
## 
## The following objects are masked from 'package:base':
## 
##     format.pval, round.POSIXt, trunc.POSIXt, units
## 
## Loading required package: aplpack
## Loading required package: tcltk
## Loading required package: quantreg
## Loading required package: SparseM
## 
## Attaching package: 'SparseM'
## 
## The following object is masked from 'package:base':
## 
##     backsolve
## 
## 
## Attaching package: 'quantreg'
## 
## The following object is masked from 'package:Hmisc':
## 
##     latex
## 
## The following object is masked from 'package:survival':
## 
##     untangle.specials
## 
## 
## Attaching package: 'UsingR'
## 
## The following object is masked from 'package:survival':
## 
##     cancer

How can I suppress this output? Note: echo=FALSE did not work.