This is a high potency vitamin d3 supplement. Vitamin d us any group of vitamins found liver and fish oils. Vitamin d is essential for calcium absorption. Also magnesium and phosphate. The sun is a great source of vitamin D. Sadly, lots of people, need help with vitamin D since their area doesnt get much sun.
This supplement hasn't given me any stomach pains. It seems to work quickly too. I haven't had to deal with a lot of body aches.