One of the most nutrient dense foods on the planet is actually liver!
Personally, I don't like the texture, so I take capsules. While nursing my oldest, my iron stores were low, which has been a problem in the past for me. I was put on ferrous sulfate at first, but switched to beef liver capsules and haven't looked back. Why?
For thousands of years, beef liver has been regarded in nearly every culture as a special food. It's packed full of iron and b vitamins, which are more bio-available than synthetic forms of b vitamin. Liver is also high in vitamin A (which is how you prevent things like measles), an excellent and digestible form of iron, and has minerals like copper and zinc. Liver is also full of collagen, which is great for our skin, nails, and hair.
Yesterday I talked about cod liver oil. Beef liver is perhaps one of the most common, but some forms of liver like pate and fois gras are higher end forms of duck/beef liver.
I personally take Ancestral Proteins beef liver capsules, but Vital Proteins is also a great brand if you're looking for it.
Iron, vitamin A, and b vitamins are highly important for immunity, adrenal function, and brain health. When people ask "but how can you keep your family healthy?" This is one of the best ways to do so!