Dr Jessica Ferguson

Lower incidence of cardiovascular disease (CVD) in the Greenland Inuit, Northern Canada and Japan has been attributed to their consumption of seafood rich in long chain omega-3 polyunsaturated fatty acids (LCn-3PUFA). While a large majority of pre-clinical and intervention trials have demonstrated heart health benefits of LCn-3PUFA, some studies have shown no effects or even negative effects. LCn-3PUFA have been shown to favourably modulate blood lipid levels, particularly a reduction in circulating levels of triglycerides. High density lipoprotein-cholesterol (HDL-C) levels are elevated following dietary supplementation with LCn-3PUFA. Although LCn-3PUFA have been shown to increase low-density lipoprotein-cholesterol (LDL-C) levels, the increase is primarily in the large-buoyant particles that are less atherogenic than small-dense LDL particles. The anti-inflammatory effects of LCn-3PUFA have been clearly outlined with inhibition of NFkB mediated cytokine production being the main mechanism. In addition, reduction in adhesion molecules (intercellular adhesion molecule, ICAM and vascular cell adhesion molecule 1, VCAM-1) and leukotriene production have also been demonstrated following LCn-3PUFA supplementation. Anti-aggregatory effects of LCn-3PUFA have been a subject of controversy, however, recent studies showing sex-specific effects on platelet aggregation have helped resolve the effects on hyperactive platelets. Improvements in endothelium function, blood flow and blood pressure after LCn-3PUFA supplementation add to the mechanistic explanation on their cardio-protective effects. Modulation of adipose tissue secretions including pro-inflammatory mediators and adipokines by LCn-3PUFA has re-ignited interest in their cardiovascular health benefits. The aim of this narrative review is to filter out the reasons for possible disparity between cohort, mechanistic, pre-clinical and clinical studies. The focus of the article is to provide possible explanation for the observed controversies surrounding heart health benefits of LCn-3PUFA.

The most common form of phytosterol (PS) fortified foods are fat spreads and dairy products. The predominant fats used are soybean/sunflower (SS) or rapeseed/canola (RC) oils and animal fat (D) in dairy products. This review aimed to investigate whether the carrier fat is a determinant of the hypocholesterolaemic effects of PS fortified foods. Databases were searched using relevant keywords and published RCTs from 1990 investigating the effects of dietary PS intervention (=¿1.5¿g per day) on total cholesterol and LDL-C were included. After methodological quality assessment and data extraction, a total of 32 RCTs (RC, n¿=¿15; SS, n¿=¿9; D, n¿=¿8) were included. As expected, all fat groups significantly reduced TC and LDL-C (p¿<¿0.01). When compared across different carrier fats, RC as the main carrier fat, reduced LDL-C significantly more than the SS spreads (p¿=¿0.01). Therefore, a combination of monounsaturated fatty acid rich spread with adequate amounts of omega-3 fatty acids (as evident in RC spreads) may be the superior carrier fat for the delivery of PS for optimal blood cholesterol-lowering. The findings of this research provide useful evidence for optimising the hypocholesterolaemic effects of PS and support further investigation into the possible mechanisms behind these findings.

Management of hyperlipidaemia remains a cornerstone therapy for the prevention of cardiovascular disease (CVD). Dietary supplementation with n-3 polyunsaturated fatty acid (PUFA) has been shown to modulate blood lipid profiles and reduce the risk of developing CVD. However, studies relating objective measures of long-term dietary n-3 PUFA intake and circulating lipid levels in older adults are limited. Thus, we aimed to determine whether there is an association between erythrocyte n-3 PUFA status (omega-3 index, O3I) and blood lipid profiles in older adults. A sample of adults aged 65-95 years who participated in the Retirement Health and Lifestyle Study was evaluated. Outcome measures included O3I (% eicosapentaenoic acid+% docosahexaenoic acid) and fasting blood lipid profiles [total cholesterol (TC), low-density lipoprotein (LDL)-cholesterol, high-density lipoprotein (HDL)-cholesterol and triglyceride (TG)]. Two hundred and seventy-six subjects were included in the analyses. The mean±SD age was 77.6±7.4 years, and 40.9% were males. O3I was significantly higher in females compared to males. O3I was inversely associated with plasma TG (P<.001) and TC/HDL-cholesterol ratio (P<.05), and positively associated with HDL-cholesterol (P<.05), in all subjects. Associations between O3I and TG were evident in both females (r=-0.250, P<.01) and males (r=-0.225, P<.05). In females only, the odds of being hypertriglyceridaemic were highest in those with lowest O3I (P=006). Trends for hypercholesterolaemia and elevated LDL risk were converse between males and females. Long-term n-3 PUFA status is associated with blood lipid profiles in older Australians. Our findings support the development and implementation of age-specific dietary strategies to reduce the risk of CVD via improving the O3I.