deciding whether to use ANOVA or t-test

I am trying to determine if I should use a t-test or ANOVA . I am reviewing a study on plums and reducing blood pressure. If my dependent variable is blood pressure, my independent variables are eating plums, eating twice as many plums, and eating no plums, then which test do I use? my text says t-tests are for 2 groups and ANOVA is for 2 or more groups. are the independent variables the groups? there are 259 test subjects.HELP!!