n-3 Polyunsaturated Fatty Acids

Many studies have examined the beneficial effect of n-3 PUFAs in the prevention and treatment of CVD. n-3 PUFAs include a-linolenic acid, eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and docosapentaenoic acid (DPA). a-Linolenic acid is mainly found in plant sources and specifically in a limited number of seeds, nuts, and their oils, such as flaxseed oil, rapeseed oil, walnut oil, and soybean oil. EPA and DHA are derived mainly from seafood such as anchovies, salmon, and mackerel. DPA is also derived from seafood but in significantly smaller amounts, and at the same time it is endogenously synthesized from DHA (USDA 2016). There are several mechanisms associated with the beneficial effect of n-3 fatty acids on CVD. Firstly, n-3 PUFAs result in the lowering of plasma triglyceride (TG) synthesis (Harris and Bulchandani 2006). n-3 PUFAs have also been associated with reduced systolic and diastolic blood pressure (Mozaffarian and Wu 2011), have antiarrhythmic effects (Endo and Arita 2016), result in improved endothelial function

TABLE 6.1

Nutrient Functions and Recommendations for Reducing the Risk of Heart Disease

Nutrient

Nutrient Functions and Recommendations

Saturated fatty acids

Dietary saturated fatty acids intake is not associated significantly with risk of CHD (Siri-Tarino et al. 2010). The effect of saturated fatty acids on CVD risk depends on the replacement nutrient (Michas et al. 2014). It is recommended that SFAs should account for <10% of total energy intake, through replacement by polyunsaturated fatty acids (Montalescot et al. 2013).

Trans fatty acids

Trans fatty acids are associated with increased levels of LDL, blood lipoprotein-a, and inflammatory factors, decreased levels of HDL, and impaired endothelial function (Mozaffarian et al. 2006). They are positively associated with CHD morbidity and mortality. It is recommended that trans-unsaturated fatty acids do not exceed 1% of total energy intake (Montalescot et al. 2013).

n-6 Polyunsaturated fatty acids

n-6 Polyunsaturated fatty acids may have a beneficial effect on cardiac death risk, and intakes of at least 5%-10% energy intake from n-6 PUFAs is associated with a reduced risk of coronary heart disease (Harris et al. 2009).

n-3 Polyunsaturated fatty acids

The consumption of n-3 polyunsaturated fatty acids from fish and fish oils has a cardioprotective effect (Endo and Arita 2016). It is recommended to consume fish at least twice a week (preferably oily fish). It is suggested to consume n-3 PUFAs from fish and fish oils rather than from food supplements (Montalescot et al. 2013).

Monounsaturated fatty acids

MUFAs as a replacement nutrient for carbohydrates and saturated fatty acids have been shown to decrease blood pressure, increase HDL cholesterol levels, and decrease hs-CRP levels (Michas et al. 2014).

Fiber

Antioxidants

Fiber intake is inversely associated with CVD mortality (Liu et al. 2015). Based on data from intervention controlled trials, it is not recommended to use antioxidant vitamin supplementation to prevent or treat CVD.

Vitamin C

It has been shown that vitamin C has no significant inverse association with cardiovascular events and all cause mortality.

Vitamin A

High plasma levels of carotenoids may be associated with reduced oxidative stress, lower levels of inflammation, improved endothelial function, and higher levels of HDL cholesterol; however, the findings are not consistent. It is not recommended to use ^-carotene supplementation in the prevention of cardiovascular disease.

Vitamin E

Vitamin E may have anti-inflammatory and cardioprotective functions. Meta-analyses have failed to support the beneficial effect of vitamin E and its supplementation for the primary prevention of cardiovascular disease is not recommended (Moyer and Force 2014).

Vitamin D

It has been shown that low blood vitamin D levels may be associated with increased risk of CHD (Grandi et al. 2010). The correction of low vitamin D levels may reduce CVD morbidity and mortality (Eilat-Adar et al. 2013). It is not recommended to use vitamin D supplements in order to prevent CVD in people with normal vitamin D levels (Eilat-Adar et al. 2013).

Polyphenolic compounds B vitamins

Polyphenolic compounds may have antioxidant and cardioprotective function; however, the evidence is limited and further research is required (Rangel-Huerta et al. 2015).

B vitamins (folate, vitamin B6, and vitamin B12) or folate supplementation can result in lower levels of homocysteine and CHD risk (Muskiet 2005). Folic acid and vitamin B supplements are not effective for the primary or secondary prevention of CVD and stroke.

(Mozaffarian and Wu 2011), and in high doses have anti-inflammatory properties and contribute to the cardioprotective effect (Endo and Arita 2016; Oh et al. 2010).

The consumption of n-3 PUFAs from fish and fish oils has a cardioprotective effect (Endo and Arita 2016). Meta-analyses of RCTs show that the consumption of n-3 PUFAs results in a significant reduction in CHD death (Marik and Varon 2009; Mozaffarian and Wu 2011). At the same time, another meta-analysis indicated that dietary intake of long-chain n-3 PUFAs and circulating long-chain n-3 PUFAs are associated with a significant decrease in coronary risk (Wen et al. 2014). A metaanalysis of cohort studies also suggests that high intake of n-3 PUFAs may augment the prevention of stroke in women but the beneficial effect was not established in men (Larsson et al. 2012). It has been shown that patients with stroke had lower erythrocyte levels of n-3 PUFAs (Park et al. 2009). Another meta-analysis showed an inverse statistically significant association between high fish consumption and the risk of stroke (Larsson and Orsini 2011). Overall, an association between n-3 PUFAs and stroke cannot be established and the evidence cannot support n-3 PUFA supplementation as a means for stroke prevention. Most studies agree that n-3 PUFA consumption at moderate levels could reduce CHD mortality compared with low or no consumption through mechanisms such as membrane modification, the regulation of proinflammatory gene expression, and the production of lipid mediators, which have been recognized to augment the protective role of PUFAs in CHD (Endo and Arita 2016; Mozaffarian and Wu 2011). As far as treatment is concerned, n-3 PUFA supplementation seems to be effective in the treatment of hypertriglyceridemia and heart failure (Nestel et al. 2015).

Guidelines recommend the consumption of fish at least twice a week, with one of the servings as oily fish (McMurray et al. 2012; Montalescot et al. 2013). The recommendation of the European Society of Cardiology is that patients with stable heart disease should increase n-3 PUFA intake through fish consumption, rather than from supplements (Montalescot et al. 2013).

Monounsaturated Fatty Acids

The main sources of MUFAs are nuts, olive oil, canola oil, high oleic safflower oil, sunflower oil, and avocado. The replacement of carbohydrates with MUFAs decreases TG, VLDL, hs-CRP, and blood pressure (BP), and increases HDL and Apo A; MUFA consumption also decreases total cholesterol and LDL (Michas et al. 2014). A meta-analysis indicated that high (>12%) MUFA diets are significantly associated with reduced systolic and diastolic BP (Schwingshackl et al. 2011). Based on the available data, the recommendations for the intake of MUFAs remain unclear (Perk et al. 2012). However, it is supported that populations at risk of CVD should continue replacing saturated fatty acids with unsaturated fat, although the type of unsaturated fat is not clear yet (Hooper et al. 2012).

 
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