As a pharmacist I often find myself engaged in lively debate focussed on contentious issues most pertinent to this profession. Advocating a nutritional stance I am regularly a lone voice swallowed up in a sea of conventional wisdom. So it was nice to see that on the topic of omega 3 fish oil consumption, of which I have been a staunch defender, I have received unlikely support from Big Pharma. They have been casting their nets for the next big heart cure, and fish oil is the catch of the day. Following their public endorsement of this often derided supplement analysts now suggest that as many as one third of adults will be prescribed fish oils by their doctors in the next few years. The question is though, what are the benefits that caused this change in heart about fish oils?
1) Inhibit Inflammation
It's an often overlooked factor in heart disease, and mistakenly so - inflammation is the underlying driver of atherosclerosis. The earliest stage of plaque formation occurs when inflammatory factors (called macrophages and T-lymphocytes) infiltrate the injured arterial wall endothelium, forming fatty streaks. In addition to this, the injured endothelium releases its own inflammation promoting factors, only to exacerbate matters.
It is the pro-inflammatory effects of insulin that largely explains why high sugar consumption is so bad for our hearts, and the inflammatory chemicals released by fat tissue that predisposes overweight individuals to developing cardiovascular and metabolic disease.
A simple blood test of one of the most common inflammation measurements - called C reactive protein - is especially effective in predicting one's risk of heart disease.
Fish oils massively dampen overall inflammation in the body. They reduce the synthesis of highly inflammatory members of what's called the eicosanoid family, as well as promoting the production of newly discovered classes of potent anti-inflammatory mediators called resolvins and protectins [1].
2) Arrest Aggregation
Platelet aggregation is key in clot formation, and with it comes a dramatically increased risk of heart attack and stroke. Fish oils exert anti-platelet effects through multiple mechanisms, the primary means; a reduction in ADP induced platelet aggregation [1]. As well as being effective in their own right, they also enhance the effects of conventional anti-platelet drug therapy.
The sex of the patient introduces an interesting consideration when selecting fish oils for their anti-platelet effects. A recent study found that men are only responsive to the omega 3 constituent EPA, not DHA, while the inverse is true for women, DHA responsive, EPA unresponsive [2].
3) Better Blood Pressure
When fish oils are consumed at doses of 3 grams omega 3 a day or more they exert a blood pressure lowering effect. The magnitude of the effect appears determined by the starting blood pressure and age of the patient, with maximal benefit achieved in hypertensive patients aged over 45 years [1].
On top of this fish oils consumption lowers heart rate in those with higher heart rates to begin with (resting heart rate > 70bpm) - confirming that fish oils effect the electrophysiology of the heart [3]. Some researchers have suggested that it is only the DHA component of fish oil which exerts this effect [4].
4) Enhanced Endothelial Function
Endothelial dysfunction of the arterial wall is a key event in the development of atherosclerosis. In older individuals and those already presenting with cardiovascular risk factors, fish oil consumption relaxes and increases the diameter of blood vessels, improving blood flow and reducing the chances of damage occurring to the artery walls [1].
5) Lower Lipids
Non-HDL-Cholesterol is widely considered the most accurate predictor of cardiovascular disease, accounting for both LDL cholesterol and VLDL cholesterol (triglycerides) - each of which is harmful. Whereas statins lower non-HDL cholesterol predominantly through lowering LDL, fish oils do so by reducing VLDL/ triglycerides [5]. They do this through a threefold action on the liver; acting as poor substrates for triglyceride synthesis, directly inhibit triglyceride synthesis, and promoting 'burning' of fats making them unavailable for making triglycerides.
In one of the most recent trials of fish oils in statin treated patients, 2 grams of a highly concentrated, bioavailable fish oil product reduced non-HDL cholesterol by 4% [6]. Whilst, at first glance, 4% may not appear a change of significant magnitude, it is worth noting that this is equivalent to what would be seen if the patient doubled their statin dose (exposing them to all the side effects that come with such increases). Upping the dose to 4 grams reduced non-HDL cholesterol 7%, the same effect as trebling the statin dose.
1. Marangoni, F. and A. Poli, Clinical pharmacology of n-3 polyunsaturated fatty acids: non-lipidic metabolic and hemodynamic effects in human patients. Atheroscler Suppl, 2013. 14(2): p. 230-6.
2. Phang, M., L.F. Lincz, and M.L. Garg, Eicosapentaenoic and docosahexaenoic acid supplementations reduce platelet aggregation and hemostatic markers differentially in men and women. J Nutr, 2013. 143(4): p. 457-63.
3. Mozaffarian, D., et al., Effect of fish oil on heart rate in humans: a meta-analysis of randomized controlled trials. Circulation, 2005. 112(13): p. 1945-52.
4. Grimsgaard, S., et al., Effects of highly purified eicosapentaenoic acid and docosahexaenoic acid on hemodynamics in humans. Am J Clin Nutr, 1998. 68(1): p. 52-9.
5. Pirillo, A. and A.L. Catapano, Omega-3 polyunsaturated fatty acids in the treatment of atherogenic dyslipidemia. Atheroscler Suppl, 2013. 14(2): p. 237-42.
6. Maki et al, A HIGHLY BIOAVAILABLE OMEGA-3 FREE-FATTY ACID REDUCES NON-HIGH DENSITY LIPOPROTEIN CHOLESTEROL IN HIGH-RISK PATIENTS TREATED WITH A STATIN AND RESIDUAL HYPERTRIGLYCERIDEMIA (ESPRIT TRIAL) 2013.