Kidney is a Green food. Green foods are safe to eat as a regular part of a diet.
Guideline related quotes related to Meat-Offal and Green throughout Geoff Bond's publications.
. . . some variety meats (such as offal, the organ meats) can contain unhealthy amounts of some substances (e.g., iron and vitamin A, which can build up excessively in the liver). ~Paleo in a Nutshell p.68
Examples of one serving include 3 oz (size of a deck of cards) cooked meat or poultry; 3 oz grilled fish; 1 egg. ~Paleo in a Nutshell p.95
For the meat, poultry, eggs, and fish group, Preferably consume two servings a day of “Green-Green” foods. If unavailable, you can consume two servings a day of “Green” foods. ~Paleo in a Nutshell p.102
For the meat, poultry, eggs, and fish group Restrict total food group servings per session to one. ~Paleo in a Nutshell p.102
For the meat, poultry, eggs, and fish group, Restrict total food group servings per day to two. ~Paleo in a Nutshell p.102
The Aborigine ate most plant food raw, but if it tasted better roasted, some was tossed into the embers of a fire. Animal food was mostly cooked. Small game, snakes, lizards, and grubs would be baked in the embers. Larger animals would be gutted and the variety meats (offal) cooked and eaten separately; the carcass would be baked whole. ~Deadly Harvest p.20
Our Pleistocene ancestors ate all parts of a slain animal, but this did not happen all that often. Many of the internal organs have wildly varying nutrient composition, depending on a number of factors: what the animal ate recently, how it was raised, and even its state of health. It is difficult, therefore, to generalize about variety meats. They are usually rich in micronutrients not found in such high concentrations in other sources. ~Deadly Harvest p.148
Specific references to Kidney throughout Geoff Bond's publications.
Kidney, tripe, and liver are low-fat meats, but liver in particular is heavily loaded with vitamin A and arachidonic acid (an omega-6 fatty acid that can cause inflammation), both of which are harmful in high doses; you should consume it with caution. ~Deadly Harvest p.148