In a recent study published in The American Journal of Clinical Nutrition, a bunch of researchers in the US investigated the impact of differing kinds and amounts of dietary fatty acids on the incidence of atherosclerotic cardiovascular diseases (ASCVDs) in a big cohort of United States (U.S.) veterans.

Study: Association of dietary fatty acids with the chance of atherosclerotic heart problems in a prospective cohort of United States veterans. Image Credit: Corona Borealis Studio / Shutterstock

Background 

ASCVDs lead global adult deaths, with weight loss program playing a vital role. Current guidelines generalize fat intake, categorizing fats (saturated, trans, cis, and conjugated) without considering individual fatty acids (FAs) unique effects. This oversimplification ignores various health impacts, evidenced by recent research difficult traditional views on dietary fats and heart health. Thus, understanding individual FAs’ specific influences on ASCVD is critical, necessitating further research for refined dietary recommendations and policies.

In regards to the study

The Million Veteran Program (MVP), initiated in January 2011, had enrolled 702,740 veterans by November 2018. This study focused on the 352,874 individuals who accomplished the MVP Lifestyle Survey, reporting on their habitual dietary intake. The study excluded participants with pre-existing conditions like ASCVD or cancer, resulting in a final cohort of 158,198 for evaluation. The median follow-up period was 3.4 years, with all procedures complying with Department of Veterans Affairs policies.

Dietary intake was assessed using a validated Food Frequency Questionnaire (FFQ), which surveyed participants on their average consumption frequency of 61 different foods over the previous 12 months. Intakes of 27 commonly consumed fatty acids and nutrients were then calculated using the Harvard University Food Composition Table. For this study, fat intake was expressed as a percentage of total day by day caloric intake.

Various covariates were assessed, including demographics, lifestyle, and medical history, gathered from the Lifestyle Surveys or the Corporate Data Warehouse and MVP Baseline. Body Mass Index (BMI) was calculated, and electronic health records were used for extra data like statin use. ASCVD outcomes were determined based on the International Classification of Diseases (ICD)9 and ICD10 codes from Veterans Affairs electronic health records, with fatalities from the National Death Index used for censoring.

The study outlined a precise chemical evaluation on the Harvard T.H. Chan School of Public Health to measure fatty acid content in oils and fats, using extraction, multiple chemical steps, and GC-FID evaluation.

The study employed Cox proportional hazard models for statistical evaluation, calculating person-time from FFQ completion to the initial ASCVD incident, coronary procedures, or censoring. Participants were divided into quintiles based on the proportion of calories from various fats. Adjustments were made for aspects like demographics, health, lifestyle, and medicine. The evaluation, conducted via SAS Enterprise Guide 8.3, also examined the results of substituting fats or macronutrients on ASCVD risk, setting statistical significance at a P value under 0.05 and applying the Bonferroni correction for multiple comparisons.

Baseline estimated day by day intake of fat classes (represented as absolute intake in grams per day) and individual FAs (represented as percentage contribution to total fat class intake) n = 158,198.

Study results 

The current study delves into the dietary patterns of 158,198 U.S. veterans with a mean age of 61, specializing in their fat consumption in relation to ASCVD risks. The participants, on average, derived 32% of their total day by day calories from fats. Throughout the follow-up, 11,771 ASCVD events were noted, predominantly ischemic heart disease (IHD), followed by ischemic cerebrovascular disease (ICVD) and peripheral arterial disease (PAD).

Significant attention was paid to the intake of saturated fatty acids (FAs), notably palmitic acid, which constituted over half of the entire saturated fats consumed. Higher saturated fat intake was observed to correlate with increased ASCVD risk, a consistent finding even after accounting for BMI. Interestingly, replacing saturated fats with cis-polyunsaturated fats reduced ASCVD risk. Nevertheless, when specific ASCVD components were considered, higher saturated fat intake was linked with PAD but not IHD or ICVD. 

The study delved deeper into the results of individual saturated FAs, revealing that while a better intake of butyric acid, a short-chain FA, was linked to a lower ASCVD risk, increased consumption of margaric acid, present in dairy and beef fats was related to a heightened risk of the identical. Palmitic acid also showed an elevated ASCVD risk association, which, nonetheless, weakened after BMI adjustment.

The evaluation prolonged to trans-unsaturated FAs, revealing that higher consumption levels were connected with a more significant likelihood of experiencing ASCVD events. This association endured for trans-monounsaturated fats even after BMI inclusion within the models, particularly increasing risks for IHD and PAD.

When considering cis-unsaturated FAs, the principal focus was on oleic acid, which comprised the vast majority of day by day cis-monounsaturated fat intake. These fats, nonetheless, showed no significant association with ASCVD risk. Alternatively, higher consumption of certain fats like palmitoleic acid and cis-vaccenic acid corresponded to increased ASCVD risk. Notably, participants with higher cis-polyunsaturated fat intake, especially linoleic acid, showed a lower likelihood of ASCVD events.

Finally, the study found that the vast majority of conjugated linoleic acid intake got here from ricinenic FA, and people in the best consumption quintile faced a greater likelihood of ASCVD events, a risk particularly pronounced for IHD and PAD. The excellent evaluation underscores the nuanced impacts of varied fatty acids on cardiovascular health, highlighting the complexity of dietary influences on disease risk and the potential health advantages of choosing healthier fats.