Adding just 1% oyster mushroom (Pleurotus ostreatus) powder to a carrot–tomato smoothie significantly increased antioxidant activity and improved intestinal uptake of key minerals, including iron, zinc, and calcium, in a Caco-2 cell model. The formulation boosted phenolic content and mineral bioaccessibility without changing the food format, showing how a small, realistic amount of mushroom powder can measurably enhance everyday nutrition in lab-based digestion and absorption tests.