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.
In a recent study analyzing the diet of 564 adult Americans, both male and female, the average intake of magnesium was less than two-thirds of the RDA for men and less than 50% of the RDA for women. This means that men, on average, are getting under 200 mg. magnesium daily and women get under 150 mg. per day.-6 times a day.). Maximum daily intake of magnesium is probably 15 mg. per kilo of ideal body weight or 6.8 mg. per pound of body weight in rare cases, under medical supervision for short periods of time. Your body must be your guide.