Leeks 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 Leeks throughout Geoff Bond's publications.
With regard to plant food, it is always best to eat it as soon as possible after harvesting and to eat it raw. That is why we put the emphasis on the consumption of salads and for them to be as fresh as possible. Be imaginative—many vegetables can form part of a mixed salad, including chopped broccoli, cauliflower, cabbage, zucchini, and leeks. ~Paleo in a Nutshell p.91
As biologist-historian Jared Diamond points out, only a few varieties of plants in the world lend themselves to being farmed and the farmer had little choice but to focus his efforts on those few. This practical reality greatly reduces the variety of foods eaten. So, it was for our first planters in Kurdistan. Instead of consuming plants from the hundreds of wild, foraged species, the farmers' diet was now limited mostly to just four farmed species— wheat, barley, lentils, and beans. As the centuries rolled by, farmers gradually domesticated some fruits (such as apricot and apple) and vegetables (such as onion and leeks), but they remained a tiny part of the diet. ~Deadly Harvest p.31
Not all underground vegetables are starchy. For example, turnip and radish, which both originated in Asia, are non-starchy, as are bulbs such as onion and garlic from Asia and the leek from the Middle East. Corms such as Chinese water chestnut are also non-starchy. Unlike the starchy roots, they mostly get their bulk from another com pound called "inulin." ~Deadly Harvest p.56