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Saturated Fat and Cardiovascular Disease…An Ongoing Conversation Piece (December 2015)

Coming from a cardiology background as a cardiac dietitian, I was trained back in the days when dietary trends followed the philosophies of Pritikin and Dr. Dean Ornish as ways to reduce the chances of developing coronary artery disease, to reverse heart disease, and also to keep one’s lipids at a healthful level.  Over the years the nutritional recommendations have changed and numerous fads have come and gone.

Currently we are faced with the discussion of saturated fat: Is butter good for you? What about coconut oil? Ghee?  The journalist Mark Bittman first announced “butter is back” March 25, 2014 in The New York Times. Bittman’s article was related to the findings published in the Annals of Internal Medicine which was led by Rajiv Chowdhury, M.D., Ph.D. from the University of Cambridge. The review concluded that there was not enough supportive evidence for current cardiovascular guidelines to recommend high intake of polyunsaturated fatty acids and what the appropriate intake of saturated fats is; however, The Academy of Nutrition and Dietetics (AND) released its position paper on fatty acids for adults in January, 2014. It recommended that adults receive not more that 7-10% of total caloric intake from saturated fat. Americans currently consume more than 11% of their total calories from saturated fat, which, according to AND, is excessive.

The research that Chowdhury did was based on 27 randomized, controlled trials and 49 observational studies, which included more than 600,000 participants in 18 countries. The studies analyzed fatty acids circulating in the blood stream or being stored in fat tissue. The participants then completed a diet history questionnaire to assess fatty acid intake.  This didn’t affect the result of the study, but other experts, strongly disagree with the results.

Some experts assert that Chowdhury’s assessment is not accurate since he excluded a number of important studies, used incorrect information from other studies, and failed to mention some of the positive findings of Walter Willet M.D., DrPh, chair of the Department of Nutrition at Harvard School of Public Health, who had completed a small portion of the study. The analysis neglected to mention two important issues: the benefits from the omega- 3 and omega-6 polyunsaturated fats and also the benefits of replacing saturated fat with polyunsaturated fats.  These omissions were likely due to the aforementioned problems.

Currently we have a considerable amount of data that show how dietary saturated fat increases the blood levels of LDL cholesterol (bad cholesterol) and also increases the risk of coronary artery disease.  In addition, there is a significant amount of data that show that a high LDL in the blood stream can increase our risk of coronary artery disease.  Another problem with Chowdhury’s study is that participants share information about their food intake using a 24-hour dietary recall method.  Such a method does not give a broad sense of what their diets are like over a period of time.

Coconut Oil- A popular trend revisited
Coconut oil is a saturated fat and we know that it can raise our LDL cholesterol (bad cholesterol) but can also increase our HDL (good cholesterol).  It is 44% lauric acid and 16% myristic acid, both being hypercholesterolemic. The data are inconclusive whether coconut oil is better or worse for you than any other saturated fat. The reason that coconut oil is popular is because it contains medium chain triglyceride (MCT), eight- and ten-carbon chains.  These fats may be metabolized differently from other triglycerides so can, therefore, lead to less fat production in the body.   It is recommended to have coconut oil in the natural form as it will contain more of it beneficial fatty acids, which could otherwise, during processing, be destroyed.

Important Considerations about Red Meat
It has been recommended that we limit red meat consumption due to the “artery clogging” saturated fats it contains.  On the other hand, a plus about red meat is that it contains oleic acid, the heart-healthy fatty acid which is also found in olive oil.  In addition, one third of the saturated fat in beef and pork is stearic acid, which is not thought to elevate our blood cholesterol levels.  The iron in red meat is known as “heme” iron and has proven to be efficiently used the body.  The vitamin B-12 and the mineral zinc are also nutritionally beneficial components of red meat.

Interesting Facts about Dairy Products
There has been quite a bit of evidence that full fat dairy is good for us due to the role fat plays in fertility and in reducing the risk of diabetes. In the August 2014 study of The Lancet Diabetes & Endocrinology the study followed 340,000 people across eight European countries and measured plasma levels of saturated fatty acids. The researchers found that fatty acid chains with an odd number of carbon atoms, especially C15:0 (pentadecanoic acid) and C17:0 (heptadecanoic acid) which are mostly in dairy products were linked to a lower chance of developing adult onset diabetes (type 2 diabetes). Even chain saturated fatty acids that were measured (myristic, palmitic, and stearic acid) were linked to an increased incidence of type 2 diabetes.

In an interview which followed the above study, Mozaffarian mentioned that more research needs to be done to conclude if odd chain saturated fatty acids have a direct correlation to reducing the risk of type 2 diabetes or if other ingredients are contributing to the results involving dairy products. He mentioned that probiotics or the fermentation of dairy products could receive some of the credit for the protective benefits.

Understanding Some Issues about LDL and HDL cholesterol…
I remember a few years ago watching an episode of CNN and seeing Dr. Sanjay Gupta discuss President Clinton after he had a heart attack. The goal of the episode was to educate the public about the most damaging type of LDL. What does that mean?  Most of us think there is only one kind of LDL and are not aware that there are several different types of LDL, some of which can be more detrimental to heart health than others.    These types are known as type-A and type-B.  Fortunately these types can be detected in specialized blood tests. People with a family history of hyperlipidemia and/or coronary artery disease might be well advised to discuss the need for this special blood test with their doctors.   I have been having these specialized labs done for a decade because of my family history.  It is an extra measure of precaution that gives me peace of mind.

It is important to know what type of LDL particles one has.  Overall, fewer LDL particles are better than having a larger number of particles.  We do not want the small, dense LDL, which is type B; the largest kind, type A, is the least harmful.   Some of the research suggests that consuming saturated fats instead of carbohydrates can reduce the number of small, dense LDL particles. This is not a helpful dietary change, but replacing saturated fat with unsaturated fats including the omega-3 and omega-6 are more effective choices.

It is also important to have a large buoyant HDL, the most protective one of which is a HDL2, according to Mark Houston, MD, MS, ABAARM, FACP, FAHA, FASH director of The Hypertension Institute of Nashville and author of What Your Doctor May Not Tell You about Heart Disease. There is one other type of HDL: small, dense HDL3 which is hypothesized to be the least protective against coronary artery disease.

Dietary recommendations are always changing as the science of nutrition advances.  If you need to cut back on fats, consider filling that gap with carbohydrates, especially fibrous ones such as legumes, and whole grains –  black or brown rice, quinoa –  or yams.  Remember that small amounts of saturated fats are necessary for overall health and well-being making it unadvisable to remove them from the diet entirely.  Also, keep the major portion of fats in your diet as the unsaturated variety.  As a final thought, make sure your diet is one that has balance, includes a variety of foods, and you consume your choices in moderation.

 

References:

  1. Bittman M. Butter is back. The New York Times website. http://www.nytimes.com/2014/03/26/opinion/bittman-butter-is-back.html. March 25, 2014. Accessed August 20, 2014.
  2. Vannice G, Rasmussen H. Position of the Academy of Nutrition and Dietetics: dietary fatty acids for healthy adults. J Acad Nutr Diet. 2014;114(1):136-153.
  3. DiNicolantonio JJ. The cardiometabolic consequences of replacing saturated fats with carbohydrates or omega-6 polyunsaturated fats: Do the dietary guidelines have it wrong? Open Heart. 2014;1. doi:10.1136/openhrt-2013-000032.
  4. Stearic acid: a unique saturated fat. National Cattleman’s Beef Association website. http://www.beefnutrition.org/CMDocs/BeefNutrition/StearicAcid.pdf. Accessed August 22, 2014.
  5. Forouhi NG, Koulman A, Sharp SJ, et al. Differences in the prospective association between individual plasma phospholipid saturated fatty acids and incident type 2 diabetes: the EPIC-InterAct case-cohort study. Lancet Diabetes Endocronol. 2014; Epub. doi:10.1016/S2213-8587(14)70146-9.
  6. Mozaffarian D. Saturated fatty acids and type 2 diabetes: more evidence to re-invent dietary guidelines. Lancet Diabetes Endocronol. 2014; Epub. doi:10.1016/S2213-8587(14)70166-4.
  7. Katz DL, Meller S. Can we say what diet is best for health? Annu Rev Public Health. 2014;35:83-103
  8. Parlesak A, Eckoldt J, Winkler K, Bode CJ, Schäfer C. Intercorrelations of lipoprotein subfractions and their covariation with lifestyle factors in healthy men. J Clin Biochem Nutr. 2014;54(3):174-180.
  9. CNN.Com/Thelastheartattack/DrSanjaygupta/September 2011

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