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@futurebird There are quite a number of uses for pine in foods across different cultures.
Examples at Serious Eats:
https://www.seriouseats.com/foraged-flavor-all-about-pine
But pine as a source of cellulose is pretty iffy for human consumption.
https://microbiomejournal.biomedcentral.com/articles/10.1186/s40168-020-00996-6
@futurebird Powdered cellulose used as an insoluble fiber filler in some reduced-calorie breads is the contemporary version. Now they add vitamins but deliberately strip out calories with what was likely wood pulp. Many of us have eaten this stuff and not known it was wood including pine.
But now we know that cellulose used as filler, anti-caking additive, and as an emulsifier in commercially-prepared foods damages gut flora thereby causing health problems.
Cellulose is commonly used in foods and bakery formulations as a source of dietary fiber or to improve their texture, usually used at less than 2% It is also used as a bulking agent in low-calorie and gluten-free baked products.
BAKERpedia (bakerpedia.com)