Foods like bone marrow, offal, dark leafy greens (hello kale!), fermented veggies, full-fat yogurt, berries, avocados, and eggs are packed with nutrients. Eggs are particularly nutritious, containing everything needed to grow a chicken.
As for supplements, D3/K2 and magnesium are crucial. Many of us are deficient in vitamin D, and magnesium is beneficial for overall health.