Do not be alarmed, but you may be eating wood pulp. Or at least an additive that started out as wood.
If you buy shredded cheeses, including brands such as Organic Valley and Sargento, or hit the drive-through at McDonald's for a breakfast sandwich or a smoothie, or douse some ribs with bottled barbecue sauce, there's likely some cellulose that's been added to your food.
Cellulose is basically plant fiber, and one of the most common sources is wood pulp. Manufacturers grind up the wood and extract the cellulose.