Western nutrition is based often on research in caucasians, more likely males and changes as new “discoveries” occur. Wrong teachings such as your example of margarine is the perfect case in point.  For over five decades (2013 trans fats banned in US)  it was pushed by almost all the nutrition powers in US with the American Heart Association being the biggest guilty party. The New York Times nutrition pages were full of advice to use margarine. The lowering of IQ when margarine is fed to infants and young children may be one of the reasons for how America is turning out. The epidemic of DJD, A Fibrillation and Macular degeneration, and other ailments in old age in the world can be blamed on this cellular poison made from near rancid vegetable oils for profit, ease of transport and to prolong shelf life of baked goods from a few weeks with butter to many months with margarine! My grandmother would not let us eat cheap "vanaspati “  or ghee from the forest Hindustan Lever name for