28 CFR § 547.20 - Policy.
The Bureau of Prisons is responsible for procuring and preparing any food or food ingredients to be served to the institution's inmate population. Except as allowed for in paragraphs (a) through (c) of this section, the Bureau requires that special food or meals prepared for and/or served to any group(s) of inmates also be served to the institution's entire inmate population. Special food or meals, as identified in paragraphs (a) through (c) of this section, may be prepared and/or served to a specific group of inmates rather than to the entire inmate population of the institution.
(a) Food items sold in the institution's commissary.
(b) Religious dietary practices as authorized in accordance with 28 CFR 548.20.
(c) Medical diet foods.