Yoga exercises could stimulate the passage of (green) food and/or (originally green) bile through your bowel, and then either the food or bile would color the stool green. If stools are loose and contain undigested food, you are losing nutrients this way.
Excessive use of magnesium supplements can be toxic. The upper limit -- the highest dose a person can take -- of magnesium supplements is: 65 mg/day for children ages 1-3. 110 mg/day for children ages 4-8. 350 mg/day for adults and children ages 9 and up.
You should be able to get all the magnesium you need by eating a varied and balanced diet. If you take magnesium supplements, don't take too much, because this could be harmful. Having 400mg or less a day of magnesium from supplements is unlikely to cause any harm.f you take manganese supplements, don't take too much, as this could be harmful. For most people, taking 4mg or less of manganese supplements a day is unlikely to cause any harm. For older people, taking 0.5mg or less of manganese supplements a day is unlikely to cause any harm.