[Lewis Thomson (OP)]

Jeff says:

Why oh why do you persist on getting on a diet nutritionist that bangs on about eating vegetables?
As you well know a human cannot solely live on vegetables, they are not the elixir of life.
Please can you get Professor Tim Noakes to talk about nutrition?

[Bored chemist]

As you well know a human cannot solely live on vegetables,

You won't get very far on a science web site by saying  things that are plainly not true, and the existence of any vegan will prove that your statement is contrafactual.

[HomeWork]

I have a lot of friends of vegans who eat only vegetables and fruits, drink only water and juices, and only sweet honey. while everyone is alive and well.

[evan_au]

Why oh why do you persist on getting on a diet nutritionist that bangs on about eating vegetables

For many years, the standard health advice for people in "Western" countries has been:
- Don't smoke
- Drink in moderation
- Eat in moderation
- Shift the balance from meat towards fruit & vegetables (or at least, from fatty meat to lean meat)
- Exercise more

There is only 1 item there that is the specialty of a nutritionist, and it definitely has them saying something about vegetables!

Two factors that emphasise vegetables in my mind is:
- Discoveries in the last decade or so about the importance of the microbiome. The fiber in vegetables gives healthy gut bacteria a comfy home.
- The land efficiency of feeding people on vegetables relative to meat products requires that we shift the balance a bit, or we will end up destroying our remaining patches of nature to turn it into grazing land.