Great question! The goal of any heart disease reversal diet, whether Dr. Esselstyn’s, Ornish or Pritikin, is to keep total calories from fat to 10% or just slightly less. While in the Pritikin days plant based milks were not as widely available, they certainly are now and are markedly healthier than dairy skim milk, which was actually included in the Orinish diet in small amounts.
Esselstyn does advise his patients that small amounts of plant milks are allowed as long as again the overall calories from fat are near the 10% level. His favorite plant based milk that he personally uses is oat milk.
There is really no data to support using one plant based milk over another. Many people like flax milk since the omega-3 fatty acids are included, however omega-3s can be easily obtained with ground flax seed or other sources.
Simply do not overdo the plant based milks and you will be fine. What you are currently doing should keep you on the path to heart disease reversal and a long, healthy life! Keep it up!