(NaturalNews) You have undoubtedly come across the advice to avoid saturated fat; it is supposed to be bad for your heart because it increases serum cholesterol levels. To lower our risk of cardiovascular disease (CVD) we are encouraged to switch to unsaturated fat from sources like vegetable oils and fish. The trouble with this advice is that total cholesterol is not a good indicator of CVD risk; the ratio of HDL ("good cholesterol") to LDL ("bad cholesterol") has greater predictive value. Saturated fat consumption raises both LDL and HDL levels, and the HDL increase largely compensates for the LDL increase.
The advice to avoid saturated fat is given with great confidence but there is surprisingly little evidence to back that recommendation; epidemiological studies of a link between fat consumption and heart disease have given mixed results in the past. A 2001 review article (1) identified just two studies that found a significant positive association between saturated fat intake and risk of coronary heart disease (CHD), and only one trial that showed a significant inverse association between polyunsaturated fat intake and CHD; these findings could not be confirmed by other investigators.
In an attempt to try and settle this matter, a meta-analysis of earlier studies of the connection between saturated fat and heart disease was undertaken (2). Twenty-one relevant articles were identified which yielded data from nearly 350,000 participants followed anywhere from five to 23 years. The authors' conclusions? Saturated fat does not cause heart disease:
"A meta-analysis of prospective epidemiologic studies showed that there is no significant evidence for concluding that dietary saturated fat is associated with an increased risk of CHD or CVD. More data are needed to elucidate whether CVD risks are likely to be influenced by the specific nutrients used to replace saturated fat."
The difference between saturated and unsaturated fats is actually not as great as these two terms imply; each type is made up of both saturated and unsaturated fatty acids, albeit in different proportions (3). Unsaturated fats (oils) typically contain 10% - 20% saturated fatty acids. The 'saturated fats' butter and lard, on the other hand, contain only about 60% and 40% saturated fatty acids, respectively; the rest is mainly monounsaturated fatty acids. Clearly, the term 'saturated fat' is misleading.
The fatty acid mix in butter and lard also happens to be quite close to the fatty acid composition in healthy human tissues; one half of the fatty acids in cell membrane phospholipids are saturated. We also make both saturated and unsaturated fatty acids from non-lipid precursors - palmitic and stearic acids and their omega-7 and omega-9 derivatives. It is therefore difficult to see why saturated fat should be a health hazard.
Of course we need a certain amount of unsaturated fats - not because they are healthier than saturated fat but because they are the best sources of essential fatty acids. But there is no epidemiological support for the claim that saturated fat is bad for us, nor is there any plausible biochemical reason why this should be so.
Siri-Tarino PW, Sun Q, Hu FB, Krauss RM. Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. Am J Clin Nutr 2010;91(3):535-546. http://dx.doi.org/10.3945/ajcn.2009.27725 "[Free Abstract]"
Helmut Beierbeck has a science background and a strong interest in all scientific aspects of health, nutrition, medicine, weight loss, or any other topic related to wellness. You can follow his ruminations on his blog http://healthcomments.info and leave comments on this or any other health-related topic.