Epidemiology, Dairy Fat and Diabetes

Epidemiology is the study of health and illness patterns in a population which can later be used to form studies for controlled studies to test specific variables(1).  What epidemiology CAN do is provide you with CORRELATIONS.  What epidemiology CANNOT do is provide you with CAUSATION.  We seem to always forget this rule, and jump to conclusions too quickly.  In a way, it makes sense to me that people are quick to do this.  With so many people sick or dying from cancer, heart disease, diabetes, and auto-immune conditions, (OH yea, don’t forget healthcare) we truly want to find the answer, which allows us to fool ourselves in thinking causation and correlations are the same.  To give you an example of these dangers I submit Exhibit A

Exhibit A

In the winter time-> Depression rates increase

In the winter time—> Beenie Hat purchases increase

Therefore depression is caused by more beenie hats! 

Obviously this is not the case, but yet went down this path for over 50 years with the lipid hypothesis. 


Anyways on to this study from HARVARD*.  This is a prospective cohort study (long-term, observational study from 1992-2006).  This observational study wanted to look at how levels of a TRANS-fatty acid name trans-palmitoleate affected major metabolic risk factors and how it related to becoming diabetic.  304 people out of 3736 people in this population developed diabetes.  Wait there are health trans fats?  Ah, yea!

Here are the results from the abstract- (I have added the bold print)

In multivariate analyses, whole-fat dairy consumption was most strongly associated with higher trans-palmitoleate levels. Higher trans-palmitoleate levels were associated with slightly lower adiposity and, independently, with higher high-density lipoprotein cholesterol levels (1.9% across quintiles; P = 0.040), lower triglyceride levels (−19.0%; P < 0.001), a lower total cholesterol–HDL cholesterol ratio (−4.7%; P < 0.001), lower C-reactive protein levels (−13.8%; P = 0.05), and lower insulin resistance (−16.7%, P < 0.001). Trans-palmitoleate was also associated with a substantially lower incidence of diabetes, with multivariate hazard ratios of 0.41 (95% CI, 0.27 to 0.64) and 0.38 (CI, 0.24 to 0.62) in quintiles 4 and 5 versus quintile 1 (P for trend < 0.001). Findings were independent of estimated dairy consumption or other fatty acid dairy biomarkers. Protective associations with metabolic risk factors were confirmed in the validation cohort.

Link to the paper- http://www.annals.org/content/153/12/790.abstract

The results are really interesting to me-

Increases HDL-C,  lower triglycerides, lower cholesterol to HDL ratio, lower insulin resistance, lower adiposity (fat tissue accumulation).

Now if you look up the Gardner et al paper on The A to Z diet trials or many other low carbohydrate diet studies these results are typical on low carbohydrate diets.  This is NOT to say that this paper proves that carbohydrates restriction caused these findings.  It doesn’t prove that at all.  In fact they were looking at an exogenous (needs to come from the diet) trans-fatty acid, and not carbohydrate restriction at all, but I find it very interesting. 

So what am I really trying to say?  Nothing.  Just wanted to bring this to everyone’s attention and let them do with it as they please. 

Take responsibility of your health.  I leave you with a quote by Muse.

“Their time is coming to an end, we have to unify and watch our flag ascend”


1. http://en.wikipedia.org/wiki/Epidemiology

*Said like I am some super posh Harvard bad-A** professor!

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