I have found I can achieve a more complete and strain free bowel evacuation by placing my feet on a stool placed in front of my toilet. I have taught my family this behaviour and we all benefit from it.
Constipation advice on the Senokot Website under the heading of practical tips shows a person achieving the posture nature intended us to use whilst having a poo.
If you Google Toilet Aids, natural constipation remedies or just Loo Stool you will find different designed products possibly worth investing in rather than dramatically adjusting your diet or life style.
Most of the medical profession seem to ignore this simple yet very effective solution.
Mr John F Stebbing Consultant Surgeon at Guildford RSCH. recommends using the above method as an affective aid for people having trouble moving their bowels.