If you are unable to obtain fresh green beans, you can still get many valuable nutrients from green beans that have been frozen or canned. We like fresh greens the best! But we realize that access to them can sometimes be a problem. When first frozen and then cooked, retention of some B vitamins in green beans (like vitamins B6 and B2) can be as high as 90%. Recent studies have shown that canned green beans, on average, lose about one third of their phenolic compounds during the canning process. They lose B vitamins as well but in the case of some B vitamins like folic acid, as little as 10%.