How does fish oil reduce triglycerides
Omega-3 fatty acids from fish oil possess the unique ability to reduce triglycerides.
There's no doubt that omega-3s do this quite effectively. After all, the FDA approved prescription fish oil, Lovaza ®, to treat a condition called familial hypertriglyceridemia, a genetic condition in which very high triglyceride levels, typically 500 mg/dl or greater, develop. Omega-3 fatty acids, prescription or otherwise, reduce triglycerides in this condition by hundreds of milligrams. While most of us don't need this much triglyceride reduction, omega-3 fatty acids can still exert substantial triglyceride reduction even when we have less marked elevations to start.
Omega-3 fatty acids stand out for their unique triglyceride-reducing property. No other fraction of fatty acids, like omega-6, monounsaturated or saturated, can match the triglyceride-reducing effect of omega-3s. Ounce for ounce, omega-3 fatty acids are at least 10-fold more potent for triglyceride reduction than any other food oil.
But why and how does fish oil reduce triglycerides?
First of all, what are triglycerides? As their name suggests, triglycerides consist of three ("tri-") fatty acids lined up along a glycerol (sugar) "backbone." Triglycerides are the form in which most fatty acids occur in the bloodstream, liver, and other organs. (Fatty acids, like omega-3, omega-6, mono- or polyunsaturated, or saturated, rarely occur as free fatty acids unbound to glycerol.) In various lipoproteins in the blood, like LDL, VLDL, and HDL, fatty acids occur as triglycerides.
When triglycerides are present at high levels (greater than 100 mg/dl), they interact with other particles in the blood and cause distorted size and function. High triglycerides are part of the reason, for instance, that small LDL particles develop, the most oxidazable and most heart disease-causing form of LDL. Triglycerides develop most commonly from excessive carbohydrates in the diet.
Of all lipoproteins, chylomicrons (the large particle formed through intestinal absorption of fatty acids and transported to the liver via the lymph system) and VLDL (very low-density lipoprotein, very low-density because they are mostly fat and little protein) particles are richest in triglycerides.
The emerging evidence suggests that omega-3 fatty acids from fish oil reduce triglycerides through:
Reduced VLDL production by the liver
Accelerating chylomicron and VLDL elimination from the blood
Activation of peroxisome proliferator-activated receptor gamma (PPAR-gamma) - Omega-3s ramp up the cellular equipment used to convert fatty acids to energy (oxidation)
In my view, given the extraordinary safety record of omega-3 fatty acids from fish oil, their wide availability and low cost, omega-3s should be first choice for triglyceride reduction when treatment is necessary. (In my cardiology and lipid consultative practice, I am always astounded at how many people are put on various drugs as the first effort to reduce triglycerides, but not fish oil.) Triglyceride-reducing effects begin with an omega-3 dose (EPA + DHA, not of the total fish oil content) of 1000 mg per day, with greater reductions at higher doses.
Because carbohydrates, such as wheat flour, cornstarch, and sugars, all increase VLDL production by the liver and thereby increase triglycerides, reducing these foods also serves to reduce triglycerides. Combine omega-3 fatty acids from fish oil with a low-carbohydrate diet and you have an extremely potent means of reducing triglycerides.