I purchased a gallon of black seed oil "nigella sativa" in October of 2011. When I first received it I started consuming it regulary, but after awhile it just sat in my refrigerator. I consumed it a few times over the years. Recently I just started consuming it again because of allergies and a cold. I read online that rancid oil can cause cancer and alzheimers? Am I at health risk from consuming this oil since its 6 years old? it pretty much smells and taste the same as when I bought it. And it was a 100 dollars a gallon...