Step 1: First blank.
The sentence is in present perfect tense describing current practices. Hence, “have integrated mindfulness” is correct. Options with “were” or “could” distort the meaning.
Step 2: Second blank.
The correct phrase is “in the treatment” A standard collocation). “For treatment” is also possible grammatically, but less precise in this formal academic context. Thus, “in the” is best.
Step 3: Third blank.
We need an article before “host.” The indefinite article “a host of” is the natural idiom. “The host” is incorrect here. So answer must contain “a.”
Step 4: Fourth blank.
To give examples, “such as” is the formal and correct academic usage. “Like” is less formal and does not fit well in this context.
Step 5: Fifth blank.
The clause is: “Number of such practitioners ________ increased substantially.” Here, subject = “Number,” which is singular. Therefore, it must take the verb “has,” not “have.”
\[
\boxed{\text{have, in the, a, such as, has}}
\]