I don't know, the linked editorial in NEJM summarises it pretty well: >However, these “positive” results need to be interpreted with caution. First, there was

I don't know, the linked editorial in NEJM summarises it pretty well: >However, these “positive” results need to be interpreted with caution. First, there was no correction for multiple comparisons, as would be required to attenuate the chance that these are spurious results, owing, in part, to the number of secondary end points. Second, these putative effects have not been consistently observed across other large, randomized trials of n−3 fatty acids.5,6 However, in one of the trials of vitamin D supplementation, post hoc analysis showed a lower incidence of cancer among women who received active supplements than among those who received placebo, excluding women who had withdrawn or in whom cancer had developed in the first year of the trial.13 Finally, the medical literature is replete with exciting secondary end points that have failed when they were subsequently formally tested as primary end points in adequately powered randomized trials. Thus, in the absence of additional compelling data, it is prudent to conclude that the strategy of dietary supplementation with either n−3 fatty acids or vitamin D as protection against cardiovascular events or cancer suffers from deteriorating VITAL signs. https://www.nejm.org/doi/full/10.1056/NEJMe1814933 https://www.nejm.org/doi/full/10.1056/NEJMe1814933