In American English it is "...an holistic approach" or "...a holistic approach." Either is acceptable. Generally, the article "a" is used for consonant sounds, and the article "an" is used for vowel...
The disease is a total affection of mind and body, the disturbance of the whole organism. Individual organs are not the cause of illness but disturbance at the inner level. Therefore instead of...
There is a difference of opinion on this. Some use "an" in front of certain words that begin with a non-silent "h", but others think it that there is no reason these words should be treated...