Heart disease risk similar for individual saturated fatty acids
medwireNews: Dietary intake of saturated fatty acids (SFAs) is associated with increased risk for coronary heart disease (CHD), with individual fatty acids making a similar contribution to risk, according to the results of two large cohort studies.
“Owing to similar associations and high correlations among individual SFAs, dietary recommendations for the prevention of coronary heart disease should continue to focus on replacing total saturated fat with more healthy sources of energy,” write study authors Qi Sun (Harvard T H Chan School of Public Health, Boston, Massachusetts, USA) and colleagues in The BMJ.
In an analysis of data from 73,147 women in the Nurses’ Health Study and 42,635 men in the Health Professionals Follow-up Study, the researchers found that overall intake of major SFAs was associated with increased risk for CHD over a median follow-up of 25.8 years for women and 21.2 years for men.
Intake of the individual SFA types – lauric acid, myristic acid, palmitic acid, and stearic acid – was highly correlated, with Spearman correlation coefficients ranging from 0.38 to 0.93. When the highest and lowest intake groups for each SFA were compared, the hazard ratios for CHD were 1.07, 1.13, 1.18, and 1.18, respectively.
“[A]round a 5% higher intake of longer chain dietary SFAs (12-18 carbons), found in hard cheese, whole milk, butter, beef, and chocolate, is associated with a 25% increased risk of coronary heart disease,” explain Russell de Souza and Sonia Anand (McMaster University, Hamilton, Ontario, Canada) in an accompanying editorial.
Using statistical models, Sun and colleagues also showed that when 1% of daily energy intake from a combination of the four SFAs was replaced with equivalent energy from polyunsaturated fat, whole grain carbohydrates, or plant protein, there was a significant 6–8% reduction in CHD risk. Replacement of palmitic acid resulted in the greatest reduction in the risk of CHD, at 10–12%.
The authors note that the use of palm oil, which contains over 40% palmitic acid, is increasingly used in food production, especially in developing countries. They believe that this trend “might lead to adverse consequences, and calls for integrated and effective solutions that involve food producers, consumers, and policymakers.”
de Souza and Anand comment that there have been inconsistencies in the results of cohort studies investigating the link between SFAs and cardiovascular disease. Although “[s]tudies of individual nutrients are essential to ensure nutritional adequacy,” they caution against dietary advice involving single nutrients.
“Advice to avoid ‘long chain, even saturated fats’ is unlikely to find its way into guidelines because this information is not required on nutrition labels, and many fatty acids share food sources. A narrow focus on SFAs might result in diet that meets one target (for example, low in saturated fat) but fails to meet another (owing to a high intake of refined carbohydrates),” the commentators say.
And they recommend that “dietary patterns might provide more appropriate information to guide food choices.”
The study authors acknowledge the limitations associated with the self-reported data that were obtained through food frequency questionnaires in their study, but conclude that their findings support current nutritional guidance to limit saturated fat intake.
Looking to the future, they say that: “The public health and clinical significance of modulating the content of individual SFAs in specific foods should be further evaluated.”
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