Actually, the Rambam says that all fresh fruits (especially citrus) are unhealthy, with the exception of figs and grapes (Hilchos Deos 4:11). In the “particularly unhealthy” category are vegetables and legumes like lentils, cabbage, leeks, onions and radishes. (Ibid, 4:9). I’m sure one can live a healthy life without these foods, but it’s hard to imagine them being sufficiently unhealthy to cut out of one’s diet.
Credit goes to my husband for finding these sources.