SIDS is probably influenced hugely by vitamin deficiency in people who have certain genetic metabolic tendencies.   For example, deficiency in vitamin B12 (particularly a form called adenosylcobalamin) can lead to problems with breathing and sleep apnea in children and adults.

B12 deficiency-related breathing problems have been known by at least some in the medical research community for a long time.   It's beyond comprehension how this is not getting the right attention, and medical research dollars, especially in respect of newborns.   B12 isn't the only vitamin that causes metabolic problems that affect respiration, however, it's one of the more common ones.   

One big problem is that current diagnostic tests used in Canada (and a lot of other countries) are not sufficient to identify these kinds of complex metabolic issues driven by nutrients.   Improved blood and urine testing protocols as well as genetic testing, when required, are needed to correctly diagnose these conditions.