The burden of cardiovascular diseases is highest in countries with low animal fat consumption

In 1953, Ancel Keys showed that coronary heart disease mortality was more prevalent in countries with a high fat consumption [1]. Though this correlation was based on an analysis of merely 6 countries, it led to the advice to consume less fat. This was followed by the advice to consume less saturated fat, using data from The Seven Countries Study [2]. Even in 2005, the Institute of Medicine (IOM) included data from The Seven Countries study in the evidence to justify the advice to consume less saturated fat [3].

Study design

I linked per capita (per person) availability of animal fat to the burden of cardiovascular diseases (CVD), including data from 170 countries. Data regarding availability of animal fat is provided by the Food and Agriculture Organization (FAO) [4]. Data regarding the burden of CVD is provided by the World Health Organization (WHO) [5].
The burden of CVD is expressed in DALYs. The measure DALY combines:
Years of life lost to premature mortality and
Years of life lost due to time lived in states of less than full health

DALY’s are measured per 100,000. E.g., we see a DALY for cardiovascular diseases of 1,525 in 2004. This means that 1,525 per 100,000 years of life were lost to premature mortality from cardiovascular diseases or from living with cardiovascular diseases in the year 2004. Global data about DALYs is only available for the year 2004.

Results

The result can be seen in figure 1.



Figure 1. Per person availability of animal fats in relation to the burden of cardiovascular diseases for the year 2004

Results seem unexpected. We can clearly see that the highest burden of cardiovascular diseases can be found in countries with the lowest availability of animal fats. The Pearson Correlation was significant (P = 0.01).

The reason for the large discrepancy is not clear to me. Several explanations are possible:
Keys examined saturated fats. I examined animal fats. This seems the most unlikely explanation.
The much larger number of countries, I included.
Keys examined coronary heart diseases. I examined CVD, which includes a larger number of diseases.
Keys examined mortality. I examined the burden of diseases. Which does not only include mortality, but also the amount of years lost due to time lived in a state of less than full health because of CVD.
Keys used disease prevalence data unadjusted for age. This does not take into account the fact that heart disease prevalence in some countries may have been higher just because the population lived longer. The DALY data I included was adjusted for age.
Changes in animal fat/saturated fat intake and/or CVD/heart disease occurring over time.

Keys’ saturated fat hypothesis

This means that Keys’ data is dismissed. The age-adjusted DALY data for CVD including a larger number amount of countries is just much more “reliable”.

Does this mean that animal fats are cardio-protective? No it doesn’t. Ecological comparisons are not able to show any causal effects. The IOM knows this. But because of a lack of studies showing any evidence for an association between saturated fats and cardiovascular diseases, data from the Seven Countries Studies was included in their report anyway. They could always point the finger to that study.

In the future, I will show what the association between animal fat availability and the burden of CVD looks like, if we adjust for strong confounding variables.

Conclusion

Some decades ago, Ancel Keys showed that coronary heart disease mortality was more prevalent in countries with high intakes of saturated fat. This “correlation” was based on data from only 7 countries. I now show that the highest burden of cardiovascular diseases is found in countries with the lowest intake of animal fats. I based my results on data from 170 countries.

http://www.foodanddisease.com/

Robert Hoenselaar is a dietitian and and research journalist.

Graham