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.
Supplementing calcium should be done in accordance with your overall intake of calcium from the diet, in an attempt to get as close to the recommended daily intake (RDI) as possible. 1  This intake is: 2  700 mg for those 1-3 years of age. 3  1,000 mg for those 4-8 years of age, as well as for adults between the ages of 19-50.