Here's a home remedy for one of the most common digestive problems—constipation—that your grandmother would recognize: castor oil.
While I wouldn't exactly call castor oil a "digestive supplement," it is highly effective at producing a good digestive cleansing. Castor oil works in two ways. First, it stimulates the muscles in your gut, moving things along. And second, it lubricates your intestinal walls, making it easier for everything to pass through.
While I never had the benefit of castor oil in my home as a child, my dad says that the taste is unforgettable—which is why I'm glad to report that castor oil is now available in capsules, from companies such as NOW Foods. Everyone's gut is a little different, so you may have experiment to find just the right dosage for you. It can take four to six hours for this natural laxative to kick in, so give it a chance to work before deciding that you need "a little more."
And, as always, remember that any laxative, even a natural laxative such as castor oil, is for once-in-a-while use only. If you're experiencing a consistent bowel problem, whether it's constipation or diarrhea, you'll get better results by working on your diet than you will by looking for chemical help.