Dietary intake and biomarkers of alpha linolenic acid and risk of all cause, cardiovascular, and cancer mortality: systematic review and dose-response meta-analysis of cohort studies

Abstract

Objective To examine the associations between dietary intake and tissue biomarkers of alpha linolenic acid (ALA) and risk of mortality from all causes, cardiovascular disease (CVD), and cancer. Design Systematic review and meta-analysis of prospective cohort studies. Data sources PubMed, Scopus, ISI Web of Science, and Google Scholar to 30 April 2021. Study selection Prospective cohort studies that reported the risk estimates for death from all causes, CVD, and cancer. Data synthesis Summary relative risks and 95% confidence intervals were calculated for the highest versus lowest categories of ALA intake using random effects and fixed effects models. Linear and non-linear dose-response analyses were conducted to assess the dose-response associations between ALA intake and mortality. Results 41 articles from prospective cohort studies were included in this systematic review and meta-analysis, totalling 1 197 564 participants. During follow-up ranging from two to 32 years, 198 113 deaths from all causes, 62 773 from CVD, and 65 954 from cancer were recorded. High intake of ALA compared with low intake was significantly associated with a lower risk of deaths from all causes (pooled relative risk 0.90, 95% confidence interval 0.83 to 0.97, I 2 =77.8%, 15 studies), CVD (0.92, 0.86 to 0.99, I 2 =48.2%, n=16), and coronary heart disease (CHD) (0.89, 0.81 to 0.97, I 2 =5.6%, n=9), and a slightly higher risk of cancer mortality (1.06, 1.02 to 1.11, I 2 =3.8%, n=10). In the dose-response analysis, a 1 g/day increase in ALA intake (equivalent to one tablespoon of canola oil or 0.5 ounces of walnut) was associated with a 5% lower risk of all cause (0.95, 0.91 to 0.99, I 2 =76.2%, n=12) and CVD mortality (0.95, 0.91 to 0.98, I 2 =30.7%, n=14). The pooled relative risks for the highest compared with lowest tissue levels of ALA indicated a significant inverse association with all cause mortality (0.95, 0.90 to 0.99, I 2 =8.2%, n=26). Also, based on the dose-response analysis, each 1 standard deviation increment in blood concentrations of ALA was associated with a lower risk of CHD mortality (0.92, 0.86 to 0.98, I 2 =37.1%, n=14). Conclusions The findings show that dietary ALA intake is associated with a reduced risk of mortality from all causes, CVD, and CHD, and a slightly higher risk of cancer mortality, whereas higher blood levels of ALA are associated with a reduced risk of all cause and CHD mortality only. Systematic review registration PROSPERO CRD42021229487.

The Regular Consumption of Nuts Is Associated with a Lower Prevalence of Abdominal Obesity and Metabolic Syndrome in Older People from the North of Spain

“…Omega-3 fatty acids are a family of essential and biologically relevant fatty acids that belong to the PUFAs, being mostly available in nuts, alfa-linolenic acid (ALA), which is metabolised to eicosapentaenoic acid and docosahexaenoic acid, with anti-inflammatory properties. In this regard, a recent meta-analysis published in 2021 by Naghshi et al [30] found that a high intake of ALA was associated with a reduced risk of mortality from all causes, CVD and coronary heart diseases. Additionally, the nuts contain phytosterols, which have an inverse relationship with blood cholesterol levels [31] and other bioactive compounds with antioxidant properties such as polyphenols and vitamin E, all of which play an important role in the prevention of cardiovascular disease [32].…”

Effects of Dietary α-Linolenic Acid Treatment and the Efficiency of Its Conversion to Eicosapentaenoic and Docosahexaenoic Acids in Obesity and Related Diseases

“…Moreover, common obesity-associated features such as dyslipidemia, hypertension, and insulin insensitivity [12][13][14] that lead to the development of metabolic syndrome and increase the risk for the development of cardiovascular and other diseases such as type 2 diabetes and cancer are not found in all obese subjects [15,16]. ALA may play an important role in obesity and related diseases as well as obesity-associated comorbidities [17][18][19], but its effects are generally inconsistent and understudied, so future Molecules 2022, 27, 4471 2 of 23 well-designed controlled clinical trials could be needed. In addition to the listed features associated with obesity, the ectopic accumulation of the fat in the liver is often present, and it can lead to the development of non-alcoholic fatty liver disease (NAFLD) [20].…”

α-Linolenic Acid and Risk of Heart Failure: A Meta-Analysis

“…Therefore, it is important to explore whether ALA has similar effects on the risk of HF. However, although previous studies showed that dietary patterns that included ALA-rich foods may reduce the risk of cardiovascular disease (10,11), the association between ALA and HF was unclear. The Physicians' Health Study has found that dietary ALA intake level showed an inverse trend towards an association with HF, (12) while other studies did not find a similar association (13)(14)(15).…”