The phrase "to use the nutrients" refers to the process of our bodies taking in the essential substances found in food and using them for various functions like growth, energy, and maintaining good health. Full definition
I create recipes using nutrient dense, real foods, with the goal of giving people the tools they need to live healthy, balanced lives. (mindbodyblueprint.com)
What that means more specifically is that your body can't use isolated vitamins nearly as well as a it can use the nutrients from healthy food that contains those vitamins. (kombuchakamp.com)