Aren't saturated fatty acids dangerous to the heart?

Saturated fatty acids: bad for the heart?

Saturated fatty acids appear not to increase the risk of heart and vascular disease, and Omega-3 polyunsaturates may not have a protective effect on heart health. Nutrition claims that have for years promoted the consumption of foods rich in Omega-3 fatty acids and discouraged that of saturated fats may need to be revised.

This is reported in research conducted at the University of Cambridge (UK) in collaboration with Harvard University in Boston (USA), and published in the journal Annals of Internal Medicine. Specifically, this is a meta-analysis, a study reporting the results of work conducted on a given topic, summarizing the evidence on the 'association between fatty acids and coronary heart disease.

Fatty acids and cardiac events

Fatty acids are the constituents of animal and plant lipids. They are classified according to length and chemical structure into: saturated, monounsaturated and polyunsaturated. Belonging to saturated fatty acids is palmitic acid, found in palm oil, meat and cheese. Among monounsaturated, the most common is oleic acid, the main component of olive oil. Polyunsaturated fatty acids are distinguished into Omega-3 and Omega-6. To the first group belong alpha linoleic acid, found mainly in flaxseed, EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), in which fish is rich. To the second group belongs, among others, linoleic acid, found mainly in vegetable oils. 

Numerous studies have shown that saturated fats cause increased blood cholesterol and thus heart risk. A diet high in saturated fatty acids among other things appears to increase the likelihood of developing cancer. In contrast, scientific evidence shows that unsaturated fatty acids, especially Omega-3, protect against the onset of cardiovascular disease, and prevent some types of cancers and cognitive dysfunction. In recent years, leading food safety agencies have recommended limiting intake of saturated fatty acids and increasing intake of polyunsaturated fatty acids to protect the heart.

Do omega-3s protect against cardiovascular risk?

The study in question looked at 82 publications on diet-related coronary heart disease risk, considering more than 600,000 people in Europe, North America, and Asia. From these analyses, it appears that reducing saturated fat in the diet per se does not help predict the risk of heart disease.The study reported that daily intake of Omega-3 has a protective effect against cardiovascular risk, but these results are not statistically significant. 

According to an author of the study, Dr. Dariush Mozaffarian of the Department of Epidemiology at Harvard University, the current findings therefore do not agree with guidelines that encourage high consumption of polyunsaturated fatty acids and low consumption of saturated fats. This is because, as has become apparent in recent years, it is erroneous to consider a single nutrient in relation to the prevention of a certain disease, but one must consider the effects of food as a whole.

Therefore, there should be a shift to food-based guidelines rather than individual nutrients. According to Richard Bazinet, professor of nutritional sciences at the University of Toronto, two issues need to be refuted: the first is that reducing saturated fatty acids may confer cardiovascular protection; the other is that not all polyunsaturated fats are effective. An example of his thinking concerns processed, low-fat turkey or chicken meats, which may have adverse effects on heart disease risk because of the high levels of sodium they contain. 

Currently the only way forward for healthy eating seems to be healthy foods, unprocessed foods, fruits and vegetables . Although scientific evidence confirms that high levels of EPA, DHA, and linoleic acid are associated with lower coronary risk, Bazinet notes that in some diets such as Canada's, linoleic acid makes up only 5 percent of the oils consumed and that oils with Omega-3 and Omega-6 such as soybean oil and canola account for 55 percent and 25 percent of the diet

A study with many limitations

It must be considered that this study does not consider individual diseases or problems, but refers to the whole of cardiovascular problems, and does not distinguish between primary prevention (that which prevents a disease) and secondary prevention (that which includes immediate diagnosis of the disease). 

Although the data were not statistically significant, the daily intakes of Omega-3, demonstrated a protective effect relevant to public health recommendations.In fact, the authors reported a 25% decrease in the risk of coronary heart problems associated with circulating EPA and DHA As well as, the administration of 1-2 grams per day of EPA + DHA, demonstrated a strong trend toward decreasing cardiovascular risk. It should be considered then, that participants in randomized clinical trials do not always follow instructions correctly, contributing to bias in the study data.

Omega-3: important components of cardioprotective diets

This study, despite the lack of statistical significance, demonstrates that high blood levels of EPA and DHA are linked to the reduction of cardiovascular events, and underscores the 'importance of the consumption of these fatty acids.EPA and DHA taken either from dietary sources, such as oily fish, or through supplementation, are important components of a healthy diet and a proper lifestyle. In fact, the study confirms that by increasing the consumption of Omega-3 and decreasing that of Omega-6, inflammatory processes slow down. 

Source: Rajiv Chowdhury, MD, PhD; Samantha Warnakula, MPhil; Setor Kunutsor, MD, MSt; Francesca Crowe, PhD; Heather A. Ward, PhD; Laura Johnson, PhD; Oscar H. Franco, MD, PhD; Adam S. Butterworth, PhD; Nita G. Forouhi, MRCP, PhD; Simon G. Thompson, FMedSci; Kay-Tee Khaw, FMedSci; Dariush Mozaffarian, MD, DrPH; John Danesh, FRCP; and Emanuele Di Angelantonio, MD, PhD. " Association of Dietary, Circulating, and Supplement Fatty Acids With Coronary Risk: A Systematic Review and Meta-analysis." Ann Intern Med. 2014;160(6):398-406-406. doi:10.7326/M13-1788