Galen is unimpressed with vegetables calling them "all unwholesome" and of "little nutriment to the body."
Whilst Celsus  provides us with a clear rank order for their nutritive value, Galen  seems unimpressed with vegetables as a whole, stating that they give “little nutriment to the body” and that they are “all unwholesome ”.
“Of vegetables the turnip and navew and all bulbs, among which I include the onion also and garlic, are stronger than the parsnip, or that which is specially called a root. Also cabbage and beet and leek are stronger than lettuce or gourd or asparagus” .
“Not only do we eat the seeds and fruits of plants, but also the plants themselves, often whole, but often only the roots, branches or young shoots, according as there is a pressing need for each. It is clear that, as well as giving little nutriment to the body, these are all unwholesome except, as I said, the spiny plants that have just emerged from the ground”.