Saturated Fat: Still Unhealthy After All These Years, Pt 1
Question: I have read that saturated fat does not cause cardiovascular disease, cancer or other degenerative diseases. Is saturated fat still relevant or not? Answer: My position on saturated fat has not changed though there have been a few meta-analyses that supposedly show that lowering saturated fat does not matter. Even the American Journal of Clinical Nutrition (AJCN) printed a detailed rebuttal showing how one of these meta-analyses was fraught with errors. Yet, that info seems to remain ignored.
Here is the rebuttal from the AJCN
A major problem with the studies used in these meta-analyses is that they did not look at any studies where the saturated fat intake was reduced anywhere enough to see an effect, which is typical of what has happened in American too.
So, just like the studies that criticize "low fat" diets, but never analyze any diet that is truly low fat (low fat, high fiber, minimally processed plant foods), these studies criticize the impact of lowering saturated fat, but never looked at any diet that truly lowered saturated fat below the recommended levels.
Another piece of the puzzle that specifically adds to why the above studies used in the meta-analyses found no relationship is because of what the subjects replaced saturated fat with. For many, it was with either hydrogenated &/or trans-fat, or, as another study pointed out, white flour, white sugar and/or highly processed food products containing these.
From the article, Replacing those saturated fats:
"Over the past several decades, the food industry has reduced the amount of saturated fat in many products, and the public has reduced the amount of saturated fat in its food consumption. However, there has been a wide variation in the types of nutrients that have replaced this saturated fat. For example, in many products saturated fats were replaced with trans fats, which have since been determined to be detrimental. And in the overall American diet, saturated fat was generally replaced with increased consumption of refined carbohydrates and grains.” (NOTE: and sugars)
Again, no surprise as this mirror exactly what happened in American during the same time period.
Also, studies on all-cause mortality trumps findings for subsets such as CHD and CVD. Most all-cause studies demonstrate a direct relation between saturated fat intake and all-cause mortality and the lower the better.
The combination of high fruit and vegetable and low saturated fat intakes is more protective against mortality in aging men than is either alone: the Baltimore Longitudinal Study of Aging.(J Nutr. 2005 Mar;135(3):556-61. )
Differences in all-cause, cardiovascular and cancer mortality between Hong Kong and Singapore: role of nutrition.(Eur J Epidemiol. 2001;17(5):469-77.)
"These differences can be most reasonably and plausibly explained by their differences in dietary habits, for example, a higher consumption of coconut and palm oil, mainly containing saturated fat, in Singapore."
Saturated fat, vitamin C and smoking predict long-term population all-cause mortality rates in the Seven Countries Study. (Int J Epidemiol. 2000 Apr;29(2):260-5.)
Comparison of two statistical approaches to predict all-cause mortality by dietary patterns in German elderly subjects. (Br J Nutr. 2005 May;93(5):709-16.)
Mediterranean dietary pattern and prediction of all-cause mortality in a US population: results from the NIH-AARP Diet and Health Study. (Arch Intern Med. 2007 Dec 10;167(22):2461-8.)
A few more problems with saturated fat
1) Saturated Fat and CVD and All Cause Death
Comparison of predictive performance of various fatty acids for the risk of cardiovascular disease events and all-cause deaths in a community-based cohort. Atherosclerosis. 2013 Sep;230(1):140-7. doi: 10.1016/j.atherosclerosis.2013.06.015. Epub 2013 Jul 12.
"Conclusions: Our data provides strong evidence to support that plasma saturated fats and trans fats can predict all-cause death and CVD more effectively than other fatty acid markers."
2) Saturated fats and the risk of stroke.
Plasma Fatty Acid Composition and Incident Ischemic Stroke in Middle-Aged Adults: The Atherosclerosis Risk in Communities (ARIC) Study. Cerebrovasc Dis. 2013 Jul 30;36(1):38-46.
"Conclusions: In this US cohort of whites, we found significant positive associations of plasma saturated and monounsaturated fatty acids, especially of palmitoleic acid, with ischemic stroke. We also found an inverse nonlinear association between linoleic acid and ischemic stroke."
Stroke. 2013 Jul 30.
"These findings suggest that individual serum trans, saturated, and monounsaturated fatty acids are positively associated with particular ischemic stroke subtypes, whereas individual n3 and n6 polyunsaturated fatty acids are inversely associated.”
3)Saturated Fat and Cancer
Saturated fatty acid metabolism is key link between cell division, cancer, and senescence in cellular and whole organism aging. Age (Dordr). 2010 Jun;32(2):231-7. Epub 2010 Jan 14. PMID: 20431990
"Elevated concentrations of palmitic acid are toxic to mitochondria and endoplasmic reticulum and can induce apoptosis without the involvement of reactive oxygen species. This has been demonstrated in many different cell types including cardiomycocytes (Hickson-Bick et al. 2002), hematopoietic cells (Paumen et al. 1997), pancreatic B-cells (Shimabukuro et al. 1998), and astrocytes (Blazquez et al. 2000). Relatively minor changes in palmitate concentration cause dramatic changes."
"It is concluded that aging in cells and whole organisms share a common initiation pathway and that cellular senescence is protective against cancer. Healthy longevity is likely to be most enhanced by factors that actively suppress excessive cell division.”
4) The North Karelia Project
Here is one more on the N Karelia Project, which you can find out more about here.
In regard to the impact of saturated fat, the two main dietary changes in this community was 1) the shift from full fat milk to low fat milk and 2) the shift from butter to vegetables oils both of which were targeted at reducing the intake of saturated fat.
"A major shift from whole to low-fat milk took place in both areas as well as a reduction in the amount of butter used on bread. The net reduction in North Karelia (difference in change compared with the reference area) in the intake of saturated fatty acids from milk and fat spreads used on bread was 20% in men and 14% in women. This reduction was similar in different age, education, and occupational groups suggesting that the dietary intervention had reached the whole community. The validity of the reported dietary changes was confirmed by parallel changes in serum cholesterol levels."
As a result of these two changes, both the risk factors for heart disease as well as death rates from heart disease declined significantly.
"Over the course of the study, mortality from CHD declined in North Karelia by 73% and by 65% throughout Finland. In men, mortality from cerebrovascular disease and lung cancer also declined in men and women and more in Karelia than Kuopio."
Lastly, if you are interested in some much more detailed critical analyses, I recommend these articles...
Saturated Fat: Still Unhealthy After All These Years.