Healthy in Hungarian is "egészséges" , which in English would represent wholesomeness in its adjective form...Interesting..
Healthful+ is not a word I've ever heard (Scot living in England). I assumed that it must be a US word. It seems I am wrong: I looked it up in Chambers (published in Edinburgh) expecting to find nothing, or 'chiefly US'; but, no, Chambers note: +adj causing or bringing good health.
By contrast, there is no entry for 'wellness'.

"healthful" is first recorded in 1398 (John of Trevisa).
"Wellness" is apparently as recent as 1654 (Lord Wariston). The OED calls it "rather a nonce-word than of settled status like illness ." But since both Thomas Carlyle and his wife used it, I'm a wee bit surprised that it's not in Chambers, which has a reputation for being quite thorough (with respect to headwords if not meanings) and which tends to favor the Scots. The OED also quotes A.C. Benson, master of Magdalen and one of the multifaceted Bensons, using it in his life of his father the Archbishop of Canterbury.

By contrast, there is no entry for 'wellness'.
Although there are a number of 'wellness clinics' (or 'centres') in the UK.
well, at least 'healthful' seems to have a long pedigree- i will no longer dismiss it as some kind of new-age neologism. thanks for the input

The terms Wellness and Healthful, when I hear them, do not make me feel well or healthy.