Due to the paucity of research and significant heterogeneity in studies, definitive conclusions about the effects of these micronutrients on HRV cannot be made at this time. However, there is accumulating evidence suggesting deficiencies in vitamins D and B-12 are associated with reduced HRV, and zinc supplementation during pregnancy can have positive effects on HRV in offspring up until the age of 5 y.
Odd they don't mention vitamin E or other antioxidants. They do cite that placebo-controlled vitamin E study in diabetics. I ought to see what other important information they've left out of the abstract.