1/2 a cup or so of Greek yogurt in a smoothie once a day is what's working for me. Skipped for 2 days and paid the price.
I read a previous post where 2 tbsp of virgin olive oil will help you go. I was surprised at how quickly she responded they it worked & she hasn't been able to go for 3 days.
I don't know if you would consider this natural, but for the fiber content, and for the nutrional supplementation, I drink one can of slim fast a day (generic is fine). You get the fluid w 20% soluable fiber a day. Not too much or too little; plus I seem to absorb soluable fiber a little better than insoluble fiber ( works better). Take care.
Lots of water, fiber, apple cider vinegar to help with digestion, and pumpkin (which is more fiber,) dark green veg. Really. Gallon of water a day. Haven't had more than one day without a bm, and haven't used any meds. I can understand not wanting to take anything.