I'm not sure which SNP or position for the APOC3 gene you are referring to.
Actually, check APOE first as it has pronounced effects. It's usually considered to be an Alzheimer's risk factor, but besides that it affects your cholesterol levels and specifically how they react to the saturated fat in your diet. See e.g. this paper or a high-level overview.
APOC3 is this.
John Ioannidis has written a very insightful and entertaining article about the current state of the movement which calls itself "Evidence-Based Medicine". The paper is available ahead of print at http://www.jclinepi.com/article/S0895-4356(16)00147-5/pdf.
As far as I can tell there is currently no paywall, that may change later, send me an e-mail if you are unable to access it.
Retractionwatch interviews John about the paper here: http://retractionwatch.com/2016/03/16/evidence-based-medicine-has-been-hijacked-a-confession-from-john-ioannidis/
(Full disclosure: John Ioannidis is a co-director of the Meta-Research Innovation Center at Stanford (METRICS), where I am an employee. I am posting this not in an effort to promote METRICS, but because I believe the links will be of interest to the community)