I always recommend butter over margarine for one simple reason - butter is food and margarine, while made from foods, is not really a food anymore! Margarine is an artificial product made by processing vegetable oil, which can create harmful compounds such as trans fats. It is always healthier to choose something as close to its natural state as possible, as food is what our bodies were made to eat.
Butter is made from milk, however, butter contains a very low level of lactose as is tolerated by many with lactose intolerance. If you work on improving your digestion overall, you should be able to handle lactose better and likely butter will not be much of an issue.
A great alternative to butter is ghee! Ghee is also known as "clarified" butter - it is butter that has been gently heated to remove milk solids (including lactose) and water. Here is a simple recipe for making your own ghee at home, which you can use in place of butter: www.wavelengthwellness.com/blog_files/homemade-ghee.html.
Kate Whimster, BCom, MIFHI, ND
Response by Kate Whimster BCom, MIFHI, ND