(16-09-11) Daily Long-Chain Omega-3 Consumption Associated with Reduced Arterial Stiffness

The familiar term "hardening of the arteries" refers to the gradual loss in blood vessel elasticity or compliance resulting from arteriosclerosis and aging. Increased arterial stiffness causes the heart to work harder, alters arterial blood pressure and affects the dynamics of blood flow. Arterial stiffness is a good predictor of cardiovascular events such as myocardial infarction and stroke, dementia, long-term increase in blood pressure and mortality. Blood pressure is a leading contributor to arterial stiffness and a risk factor for stroke and cardiovascular disease. However, measuring arterial stiffness improves the ability to predict cardiovascular risk. Noninvasive measurement of pulse wave velocity-the difference in the rate of blood flow between the femoral and carotid arteries-is considered the gold standard for the assessment of arterial stiffness (Figure). The slower the pulse wave velocity, the more elastic the arteries. Pulse wave analysis, which measures central blood pressure and is considered a reflection of arterial stiffening throughout the arterial tree, is also widely used to assess arterial stiffness.Nutrition, diet and lifestyle factors affect arterial stiffness through their effects on endothelial cell function, such as the production and release of vasoactive substances like nitric oxide and their influences on inflammation and oxidative stress. High consumption of fruits and vegetables over 27 years was associated with significantly lower arterial stiffness in Finnish adults. A nutritionally poor diet rich in meat and alcohol and low in micronutrients was associated with greater pulse wave velocity and arterial stiffness in a sample of middle-aged French adults. Other lifestyle factors such as smoking and physical inactivity contribute to greater arterial stiffness.Long-chain omega-3 PUFAs (n-3 LC-PUFAs) are obvious candidates for the modification of arterial stiffness because of their ability to improveendothelial function and reduce markers of subclinical inflammation. Eicosapentaenoic acid has also been associated with improved arterial elasticity after a high-fat meal. However, results of n-3 LC-PUFA supplementation on endothelial function in healthy individuals have been inconsistent. Recently, a randomized controlled study in a small number of healthy individuals with moderate hypertriglyceridemia reported no effect of low or high doses of n-3 LC-PUFAs on endothelial function or inflammatory status after 8 weeks of supplementation. Thus, a systematic review of randomized controlled trials on the effects of n-3 LC-PUFAs on arterial stiffness is timely.This review selected trials with at least 15 participants per group, a nonactive control and a validated measure of arterial stiffness, such as pulse wave velocity. The authors assessed the quality of the methods in each study according to the augmented Jadad scale and calculated effect sizes for each trial based on the differences between the placebo and intervention groups. The review included 38 of the 75 randomized controlled trials considered relevant. The studies were grouped according to interventions with animal foods (11), nutrients (15) or plant foods (12).The animal-food trials included 9 studies on n-3 LC-PUFAs and 2 on fermented milk. All but one of the n-3 PUFA trials were long-term studies from 1.5 to 25 months. Of these 8 studies, 7 reported improved pulse wave velocity or arterial compliance with n-3 LC-PUFAs and one reported no effect. The effect sizes in the chronic n-3 LC-PUFA studies ranged from small to large. There were no trials with alpha-linolenic acid, but a recent report from the U.K. found no differences in pulse waveform analysis of arterial stiffness when results from 4 weeks of modest walnut supplementation were compared with the control group in healthy participants.The reviewers concluded that chronic supplementation with n-3 LC-PUFAs was efficacious in reducing pulse wave velocity and increasing arterial compliance. Most of the participants in these studies were overweight, diabetic, dyslipidemic or hypertensive. In the one trial in healthy participants, n-3 LC-PUFAs did not affect arterial compliance. The authors noted that the lowest efficacious dose of n-3 LC-PUFAs was 540 mg EPA plus 360 mg DHA daily and that the effect size of the combined n-3 LC-PUFAs was greater than with EPA alone. The effects of n-3 LC-PUFAs also appearindependent of changes in blood pressure.The value and timeliness of this review highlights another effect of n-3 LC-PUFAs in reducing the risks associated with cardiovascular disease-the reduction in arterial stiffness. As this condition is highly predictive of future adverse cardiovascular events, dementia and death, ensuring a moderate intake of n-3 LC-PUFAs, at least 900 mg/day would be wise dietary insurance, especially among individuals at increased risk of cardiovascular disease.
Pase MP, Grima NA, Sarris J. The effects of dietary and nutrient interventions on arterial stiffness: a systematic review.

Source: Am J Clin Nutr2011;93:446-454 [Pubmed]

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