One cup of beet greens has just 39 calories and no fat but contains 220 percent of your daily allowance of vitamin A and 60 percent of your RDI of vitamin C. The leaves are packed with vitamins, minerals, and antioxidants including carotenoids, flavonoid anti-oxidants,
Beets, chard, spinach, collards, parsley and other of the really good for you, high in anti oxidant foods like blackberries, blueberries, strawberries, are high in oxalates. Unless you have kidney stones or gout or some rare health conditions ( e.g. absorptive hypercalciuria) that is not a reason to avoid them.
"Oxalates are naturally-occurring substances found in plants, animals, and in humans. In chemical terms, oxalates belong to a group of molecules called organic acids, and are routinely made by plants, animals, and humans. Our bodies always contain oxalates, and our cells routinely convert other substances into oxalates. For example, vitamin C is one of the substances that our cells routinely convert into oxalates. "
Even in people with calcium oxalate stones. "It is not clear from the research, however, that restriction of dietary oxalate helps prevent formation of calcium oxalate stones in individuals who have previously formed such stones. Since intake of dietary oxalate accounts for only 10-15% of the oxalate that is found in the urine of individuals who form calcium oxalate stones, many researchers believe that dietary restriction cannot significantly reduce risk of stone formation. ...
intake of protein, calcium, and water influence calcium oxalate stone formation as much as, or more than intake of oxalate. Finally, some foods that have traditionally been assumed to increase stone formation because of their oxalate content (like black tea) actually appear in more recent research to have a preventive effect.
https://www.whfoods.com/genpage.php?tname=george&dbid=48
everyone has to figure out this kind of stuff and what is important about diet for themselves, I just don't want people to get scared off of eating some of the world's most nutritious foods unnecessarily.