Liver counts as one of the most nutritious foods available. Far better than our old friend broccoli. lol.
But as someone said above, don't have it too often. It is sooooo nutritious it can overload you with some vitamins.
Once a week or so, is fine.
@therower
the beef bones thing is because of bone broth. Good for low carbers to get certain minerals, and very good for health on quite a few levels.
I get mine from the butchers at the end of the road. I think the poor love believes I am going to give them to the dogs (and I do give SOME of them to the mutts), but the majority go into my slow cooker and simmer with exquisite slowness for about 24 hours. A tablespoon of cider vinegar in the water causes all the nutrition to leach out of the bones, and into the liquid, while things like the cartilage dissolve. Then you just strain the bones out and use the liquid however you like - stock for soups and stews, drink it by the mug, freeze it and keep it for later.
If you google 'Bone Broth' you will find quite a cult following nowadays. I don't do the cult thing, but I must say it comes in very useful at times, and can taste absolutely delicious.
(My butcher charges £1 a carrier bag for the bones. Sometimes a bag can contain about 6-8 skeletal chicken carcasses or a huge amount of pork or beef ribs. With quite a lot of the meat left on.)