If you have watched my video addressing the relationship between cholesterol and cancer, you know that I have attributed any observations of low cholesterol among cancer patients to reverse causation. In apparent contradiction of this view are the recently announced results of a study lead by Dr Paul Lavigne which calls into doubt the reverse causation hypothesis. I am not aware of any other study which has shown a relationship to exist between low LDL and cancer over such a long time span (18.7 years). In contrast, a 1987 study based on NHANES data documented a similar association extending only six years prior to cancer diagnosis. Therefore, this paper will surely reignite debate over the reverse causation hypothesis. As of this writing, this story has yet to be exploited by the cholesterol confusionists to promote dietary saturated fat. Nevertheless, I would like to offer a few words of caution to those who might misinterpet this news.
Here are a few considerations which should temper any overheated conclusions based on this announcement:
- These results were announced at a conference. They have yet to appear in a peer-reviewed journal.
- The LDL levels observed were "not that low," first assessed at 90-100 mg/dL and rising from there. Vegans have been observed to have LDL scores around 70 mg/dL.
- Low cholesterol levels have been associated with a decreased risk of aggressive prostate cancer. Exeriments in mice have supported this association.
- Other studies support the reverse causation hypothesis. This study from my video is the best of those, in my estimation.
- Of course, cholesterol-raising animal foods have been positively associated with cancer in some studies. I am not aware of any such studies associating high saturated fat consumption with a lower risk of cancer. Vegans and vegetarians appear to generally have lower rates of cancer than omnivores. (I will address the exception of colorectal cancer in the EPIC-Oxford study in a future post.)
- The study does not address the cause of the association they found. An unknown mechanism may exist which promotes cancer and incidentally lowers LDL. No responsible person proposes that cholesterol levels should be raised through diet to avoid cancer. The relationship between high LDL and increased heart disease incidence is well established.
The confusionist blogosphere is usually quick to make too much of anomalous and unexpected findings. You shouldn't fall into the same trap.