Claim: Saturated Fats are Not Unhealthy

The claim: Saturated fats are not unhealthy. The claim that it would be, widely circulated in dietary advice, is based on bad science. We have no evidence that saturated fat consumption is linked to heart diseases.

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The response: There are good reasons to believe that saturated fats are associated with heart diseases, but recent studies have painted a much more complex picture than the simple saturated fats bad, unsaturated fats good often proclaimed. Reducing saturated fat intake for people with an increased heart disease risk remains a good idea, but infrequent consumption of saturated fats is likely not a big problem.

Terminology

Dietary fatty acids can be broadly categorized into two groups, saturated fat and unsaturated fat.

Unsaturated fats can be further broken down into monounsaturated fat, polyunsaturated fat and trans fat. They can also be distinguished by the position of double bonds in the chemical structure, and are then called omega-3, omega-6 and omega-9 fatty acids.

As a very rough rule of thumb, saturated fat is usually from animal sources while unsaturated fat is from plant sources. This is not always correct, for example coconut oil has more saturated fat per 100g than butter, but in general, this holds true.

That it is relevant to distinguish this large amount of subgroups among fats should already make it clear that the whole topic is not simple at all.

Heart Disease Risk

We know from studies that saturated fats increase cholesterol,[1]Prof. Dr. Heiner Boeing, Dr. Anja Brönstrup, Dr. Sabine Ellinger, Prof. Dr. Hans Hauner, Prof. Dr. Anja Kroke, PD Dr. Jakob Linseisen, Dipl. oec. troph. Anja Schienkiewitz, Dr. Matthias Schulze, Prof. Dr. Peter Stehle, Prof. Dr. Günther Wolfram (2006). Fettkonsum und Prävention ausgewählter ernährungsmitbedingter Krankheiten. and increased cholesterol is associated with higher heart disease risk factors.[2]D R, Jr Jacobs, D Wentworth, J D Neaton, J D Cohen, H Iso (1989-04-06). Serum cholesterol levels and six-year mortality from stroke in 350,977 men screened for the multiple risk factor intervention trial. The New England journal of medicine 320 (14): 904-910. doi:10.1056/NEJM198904063201405, ISSN 0028-4793. We also know why this is, because type-B low-densitiy lipoprotein can transport fat molecules into artery walls, leading to atherosclerosis. This paints a pretty clear picture and is the basis for the dietary advice against saturated fat consumption.

But we had problems establishing the full causality in long-term experiments in real world situations. Some studies were able to show a weak correlation between saturated fatty acid consumption and coronary heart diseases,[3]Jody Miller, C. Murray Skeaff (2009). Dietary Fat and Coronary Heart Disease: Summary of Evidence from Prospective Cohort and Randomised Controlled Trials. Annals of Nutrition and Metabolism 55 (1-3): 173-201. doi:10.1159/000229002, ISSN 1421-9697, 0250-6807. Retrieved 2013-08-10.[4]Qi Sun, Frank B Hu, Ronald M Krauss, Patty W Siri-Tarino (2010-03). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. The American journal of clinical nutrition 91 (3): 535-546. doi:10.3945/ajcn.2009.27725, ISSN 1938-3207. others had difficulties showing such a link at all.[5]Prof. Günther Wolfram (2010-03). Aktuelle Meta-Analysen und systematische Übersichtsarbeiten bestätigen DGE-Leitlinie zum Fettkonsum.

The direct and simple causality of saturated fats causing heart diseases is likely too simple.[6]Stephen R. Daniels, Robert H. Eckel, Marguerite Engler, Barbara V. Howard, Ronald M. Krauss, Alice H. Lichtenstein, Frank Sacks, Sachiko St Jeor, Meir Stampfer, Robert H. Eckel, Scott M. Grundy, Lawrence J. Appel, Tim Byers, Hannia Campos, Greg Cooney, Margo A. Denke, Barbara V. Howard, Eileen Kennedy, Ronald M. Krauss, Penny Kris-Etherton, Alice H. Lichtenstein, Peter Marckmann, Thomas A. Pearson, Gabriele Riccardi, Lawrence L. Rudel, Mike Rudrum, Frank Sacks, Daniel T. Stein, Russell P. Tracy, Virginia Ursin, Robert A. Vogel, Peter L. Zock, Terry L. Bazzarre, Julie Clark, Penny Kris-Etherton (2001-02-20). Summary of the Scientific Conference on Dietary Fatty Acids and Cardiovascular Health Conference Summary From the Nutrition Committee of the American Heart Association. Circulation 103 (7): 1034-1039. doi:10.1161/01.CIR.103.7.1034, ISSN 0009-7322, 1524-4539. Retrieved 2013-08-13. But the underlying, well-understood associations do not just become invalid this way, the lack of a clear effect needs to be explained. This is where the main medical debate is currently happening.

Some researchers claim that the basic causality is misunderstood.[7]Anthony Colpo (2005). LDL Cholesterol: "Bad" Cholesterol, or Bad Science?. Journal of American Physicians and Surgeons 10 (3): 83–89. Others try to distinguish more finely between the groups, arguing about lipid molecule sizes in addition to the types.

Again others think the observed lack of effects is because it’s important what the saturated fats are replaced with.[4]Qi Sun, Frank B Hu, Ronald M Krauss, Patty W Siri-Tarino (2010-03). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. The American journal of clinical nutrition 91 (3): 535-546. doi:10.3945/ajcn.2009.27725, ISSN 1938-3207. For example, we have good reasons to believe that replacing saturated fats with poly-unsaturated fats reduces health risks, but replacing them with mono-unsaturated fats or carbohydrates does not seem to have a major effect.[8]Eilis J O'Reilly, Berit L Heitmann, Mark A Pereira, Katarina Bälter, Gary E Fraser, Uri Goldbourt, Göran Hallmans, Paul Knekt, Simin Liu, Pirjo Pietinen, Donna Spiegelman, June Stevens, Jarmo Virtamo, Walter C Willett, Alberto Ascherio, Marianne U Jakobsen (2009-05). Major types of dietary fat and risk of coronary heart disease: a pooled analysis of 11 cohort studies. The American journal of clinical nutrition 89 (5): 1425-1432. doi:10.3945/ajcn.2008.27124, ISSN 1938-3207.[9]Renata Micha, Sarah Wallace, Dariush Mozaffarian (2010-03-23). Effects on Coronary Heart Disease of Increasing Polyunsaturated Fat in Place of Saturated Fat: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. PLoS Med 7 (3): e1000252. doi:10.1371/journal.pmed.1000252. Retrieved 2013-08-10.[10]Dariush Mozaffarian, Daan Kromhout, Alain G. Bertoni, Christopher T. Sibley, David R. Jacobs, Jennifer A. Nettleton, Marcia C. de Oliveira Otto (2012-08-01). Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis. The American Journal of Clinical Nutrition 96 (2): 397-404. doi:10.3945/ajcn.112.037770, ISSN 0002-9165, 1938-3207. Retrieved 2013-08-10.[11]Victor L. Fulgoni, Debra R. Keast, Keigan Park, Nancy Auestad, Peter J. Huth (2013-08-08). Major food sources of calories, added sugars, and saturated fat and their contribution to essential nutrient intakes in the U.S. diet: data from the national health and nutrition examination survey (2003–2006). Nutrition Journal 12 (1): 116. doi:10.1186/1475-2891-12-116, ISSN 1475-2891. Retrieved 2013-09-20.

Another explanation is that long-term studies suffer from low accuracy, especially when it comes to assessing dietary intake, but also because they typically involve multiple advice, the results will be difficult to assess. Careful analysis of the long-term studies shows that there indeed is an association, even if it is not very clear.[3]Jody Miller, C. Murray Skeaff (2009). Dietary Fat and Coronary Heart Disease: Summary of Evidence from Prospective Cohort and Randomised Controlled Trials. Annals of Nutrition and Metabolism 55 (1-3): 173-201. doi:10.1159/000229002, ISSN 1421-9697, 0250-6807. Retrieved 2013-08-10. The same argument about the low accuracy of long-term studies can be brought up against the positive correlation, too, though.[7]Anthony Colpo (2005). LDL Cholesterol: "Bad" Cholesterol, or Bad Science?. Journal of American Physicians and Surgeons 10 (3): 83–89.

Finally, some researchers point out that foods that provide saturated fats in the typical diet are also sources for significant amounts of essential nutrients, indicating that simply reducing saturated fats without emphasis on what it should be replaced with could have other less beneficial side effects, even if saturated fats themselves indeed have negative health effects.[11]Victor L. Fulgoni, Debra R. Keast, Keigan Park, Nancy Auestad, Peter J. Huth (2013-08-08). Major food sources of calories, added sugars, and saturated fat and their contribution to essential nutrient intakes in the U.S. diet: data from the national health and nutrition examination survey (2003–2006). Nutrition Journal 12 (1): 116. doi:10.1186/1475-2891-12-116, ISSN 1475-2891. Retrieved 2013-09-20.[9]Renata Micha, Sarah Wallace, Dariush Mozaffarian (2010-03-23). Effects on Coronary Heart Disease of Increasing Polyunsaturated Fat in Place of Saturated Fat: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. PLoS Med 7 (3): e1000252. doi:10.1371/journal.pmed.1000252. Retrieved 2013-08-10.

Summary

The exact extent of the correlation is unclear, but it would be wrong to say that there is no evidence at all. There is likely a small reduction in risk associated with replacing saturated fats with unsaturated fats, especially for people with an already increased risk of heart diseases.[12]Carolyn D Summerbell, Julian P T Higgins, Rachel L Thompson, Nigel E Capps, George Davey Smith, Rudolph A Riemersma, Shah Ebrahim, Lee Hooper (2001-03-31). Dietary fat intake and prevention of cardiovascular disease: systematic review. BMJ : British Medical Journal 322 (7289): 757-763. ISSN 0959-8138. Retrieved 2013-08-10.

For people without such an already increased risk, infrequent consumption of saturated fats should not be cause for major concern.

Further Reading

• Wikipedia: Saturated fat and cardiovascular disease controversy
• Whole Health Source: Does Dietary Saturated Fat Increase Blood Cholesterol?

Bibliography

1. ^ Prof. Dr. Heiner Boeing, Dr. Anja Brönstrup, Dr. Sabine Ellinger, Prof. Dr. Hans Hauner, Prof. Dr. Anja Kroke, PD Dr. Jakob Linseisen, Dipl. oec. troph. Anja Schienkiewitz, Dr. Matthias Schulze, Prof. Dr. Peter Stehle, Prof. Dr. Günther Wolfram (2006). Fettkonsum und Prävention ausgewählter ernährungsmitbedingter Krankheiten.
2. ^ D R, Jr Jacobs, D Wentworth, J D Neaton, J D Cohen, H Iso (1989-04-06). Serum cholesterol levels and six-year mortality from stroke in 350,977 men screened for the multiple risk factor intervention trial. The New England journal of medicine 320 (14): 904-910. doi:10.1056/NEJM198904063201405, ISSN 0028-4793.
3. ^ a b Jody Miller, C. Murray Skeaff (2009). Dietary Fat and Coronary Heart Disease: Summary of Evidence from Prospective Cohort and Randomised Controlled Trials. Annals of Nutrition and Metabolism 55 (1-3): 173-201. doi:10.1159/000229002, ISSN 1421-9697, 0250-6807. Retrieved 2013-08-10.
4. ^ a b Qi Sun, Frank B Hu, Ronald M Krauss, Patty W Siri-Tarino (2010-03). Meta-analysis of prospective cohort studies evaluating the association of saturated fat with cardiovascular disease. The American journal of clinical nutrition 91 (3): 535-546. doi:10.3945/ajcn.2009.27725, ISSN 1938-3207.
5. ^ Prof. Günther Wolfram (2010-03). Aktuelle Meta-Analysen und systematische Übersichtsarbeiten bestätigen DGE-Leitlinie zum Fettkonsum.
6. ^ Stephen R. Daniels, Robert H. Eckel, Marguerite Engler, Barbara V. Howard, Ronald M. Krauss, Alice H. Lichtenstein, Frank Sacks, Sachiko St Jeor, Meir Stampfer, Robert H. Eckel, Scott M. Grundy, Lawrence J. Appel, Tim Byers, Hannia Campos, Greg Cooney, Margo A. Denke, Barbara V. Howard, Eileen Kennedy, Ronald M. Krauss, Penny Kris-Etherton, Alice H. Lichtenstein, Peter Marckmann, Thomas A. Pearson, Gabriele Riccardi, Lawrence L. Rudel, Mike Rudrum, Frank Sacks, Daniel T. Stein, Russell P. Tracy, Virginia Ursin, Robert A. Vogel, Peter L. Zock, Terry L. Bazzarre, Julie Clark, Penny Kris-Etherton (2001-02-20). Summary of the Scientific Conference on Dietary Fatty Acids and Cardiovascular Health Conference Summary From the Nutrition Committee of the American Heart Association. Circulation 103 (7): 1034-1039. doi:10.1161/01.CIR.103.7.1034, ISSN 0009-7322, 1524-4539. Retrieved 2013-08-13.
7. ^ a b Anthony Colpo (2005). LDL Cholesterol: "Bad" Cholesterol, or Bad Science?. Journal of American Physicians and Surgeons 10 (3): 83–89.
8. ^ Eilis J O'Reilly, Berit L Heitmann, Mark A Pereira, Katarina Bälter, Gary E Fraser, Uri Goldbourt, Göran Hallmans, Paul Knekt, Simin Liu, Pirjo Pietinen, Donna Spiegelman, June Stevens, Jarmo Virtamo, Walter C Willett, Alberto Ascherio, Marianne U Jakobsen (2009-05). Major types of dietary fat and risk of coronary heart disease: a pooled analysis of 11 cohort studies. The American journal of clinical nutrition 89 (5): 1425-1432. doi:10.3945/ajcn.2008.27124, ISSN 1938-3207.
9. ^ a b Renata Micha, Sarah Wallace, Dariush Mozaffarian (2010-03-23). Effects on Coronary Heart Disease of Increasing Polyunsaturated Fat in Place of Saturated Fat: A Systematic Review and Meta-Analysis of Randomized Controlled Trials. PLoS Med 7 (3): e1000252. doi:10.1371/journal.pmed.1000252. Retrieved 2013-08-10.
10. ^ Dariush Mozaffarian, Daan Kromhout, Alain G. Bertoni, Christopher T. Sibley, David R. Jacobs, Jennifer A. Nettleton, Marcia C. de Oliveira Otto (2012-08-01). Dietary intake of saturated fat by food source and incident cardiovascular disease: the Multi-Ethnic Study of Atherosclerosis. The American Journal of Clinical Nutrition 96 (2): 397-404. doi:10.3945/ajcn.112.037770, ISSN 0002-9165, 1938-3207. Retrieved 2013-08-10.
11. ^ a b Victor L. Fulgoni, Debra R. Keast, Keigan Park, Nancy Auestad, Peter J. Huth (2013-08-08). Major food sources of calories, added sugars, and saturated fat and their contribution to essential nutrient intakes in the U.S. diet: data from the national health and nutrition examination survey (2003–2006). Nutrition Journal 12 (1): 116. doi:10.1186/1475-2891-12-116, ISSN 1475-2891. Retrieved 2013-09-20.
12. ^ Carolyn D Summerbell, Julian P T Higgins, Rachel L Thompson, Nigel E Capps, George Davey Smith, Rudolph A Riemersma, Shah Ebrahim, Lee Hooper (2001-03-31). Dietary fat intake and prevention of cardiovascular disease: systematic review. BMJ : British Medical Journal 322 (7289): 757-763. ISSN 0959-8138. Retrieved 2013-08-10.