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.
Take Magnesium Supplements. 1  The RDA (the minimum amount needed) for magnesium is about 300 mg a day. Most of us get far less than 200 mg. 2  Some may need much more depending on their condition. 3  Most people benefit from 400 to 1,000 mg a day.