Green beans is a Green food. Green foods are safe to eat as a regular part of a diet.
Guideline related quotes related to Non-Starchy and Green throughout Geoff Bond's publications.
Eat at least 2 3/4 lbs of mixed salad and vegetables per day, consisting of "Green-Green” and “Green” foods. Of these, at least 3/4 lb should be mixed salad. Also include at least 5 cups of “Green-Green” leafy vegetables or 2 1/2 cups of other vegetables per week. ~Paleo in a Nutshell p.102
Specific references to Green beans throughout Geoff Bond's publications.
Low-starch vegetables should be served five times daily. These are the usual items we call vegetables, such as green beans, broccoli, and kale— with the exception of potato, of course. We should also go easy on sweet potato, carrots, and peas, which are starchy-sugary and moderately glycemic. ~Paleo in a Nutshell p.48
Conforming non-starchy, colored plant foods are foods that are low-glycemic, rich in micronutrients and fiber, and harmless with regard to anti-nutrients and antigens. Broadly, they include most salad foods, such as lettuce, onions, cucumber, radish, and mushrooms, and they also include colored vegetables, such as broccoli, green beans, bell peppers (sweet peppers), and Brussels sprouts. These are considered "Green-Green," "Green," and "Green-Amber." Under "Green-Green," we have separated out the vegetables that have the high concentrations of background micronutrients that our ancient ancestors delighted in. You can have unlimited consumption of these foods, and the ideal is up to two pounds (900 g) per day. ~Paleo in a Nutshell p.62
At a restaurant, If green beans, broccoli, spinach, or any other green vegetable is available, ask for double portions. ~Paleo in a Nutshell p.90
The other methods of preserving plant food are to be avoided: Freeze-dried (packet soups), canned (peas, green beans), pickled in salt (gherkins), syruped (fruit jams and jellies), and fermented (sauerkraut). That is not to say you can never eat these things, just do not think that they are proper food. Foods pickled in vinegar (such as onions) have lost many nutrients, but at least the pickling does not add undesirable chemicals. ~Paleo in a Nutshell p.92