Diet is a modifiable risk factor for cardiovascular disease. For example, diets rich in polyunsaturated fatty acids (PUFAs) are generally thought to be beneficial for heart health. Omega-3 PUFAs, also called n-3 PUFAs, are involved in multiple biological pathways. These pathways include coagulation, muscle function, cellular transport, and cell division and growth, all of which affect heart health.
The 3 major omega-3 PUFAs are eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and alpha-linolenic acid (ALA). Another omega-3 PUFA, docosapentaenoic acid (DPA), is an intermediate metabolite formed during the interconversion of EPA and DHA. Fish oil and fatty fish such as salmon, mackerel, herring, and tuna are the primary dietary sources of EPA and DHA. ALA is found in plant-based foods such as green leafy vegetables, beans, and vegetable oils; after ingestion, ALA is metabolized to EPA and then, though very inefficiently, to DHA.
Because of inter-individual differences in genetics and metabolism, dietary intake of omega-3 PUFAs may not provide reliable estimates of their concentration in the body. These differences may generate higher levels of omega-3 PUFAs in some people, regardless of the source of fatty acids. Thus, blood testing provides a more direct and accurate assessment of the levels of these fatty acids in the body.
- Brenna JT, Salem N Jr, Sinclair AJ, et al. α-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans. Prostaglandins Leukot Essent Fatty Acids. 2009;80:85-91.
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- Albert CM, Campos H, Stampfer MJ, et al. Blood levels of long-chain n-3 fatty acids and the risk of sudden death. N Engl J Med. 2002;346:1113-1118.
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OmegaCheck = [(EPA + DPA + DHA) ÷ total PLFA] x 100
The cardiovascular disease risks associated with OmegaCheck values are shown in the Table. Thresholds were established by stratifying LC/MS/MS reference range data into quartiles. Previous population-based studies have shown a dose-dependent decrease in risk with increasing levels of omega-3 fatty acids. Relative to individuals in the highest quartile, individuals in the lowest quartile are at highest risk and those in the second and third quartiles (combined in the Table) are at moderate risk.5,9
Table: Interpretation of OmegaCheck Values
OmegaCheck Value (% by weight)
Cardiovascular Disease Risk Level
Consumption of foods high in omega-3 fatty acids (EPA and DHA), dietary supplements containing omega-3 fatty acids, and prescription omega-3 fatty acids can increase the OmegaCheck value.
A high omega-6/omega-3 ratio is associated with a higher risk of major coronary events but should be interpreted with caution because it does not differentiate fatty acids that have different physiologic properties (eg, effect on platelet function and lowering triglycerides).
A higher AA/EPA ratio is associated with higher risk for major coronary events (sudden cardiac death, fatal or nonfatal myocardial infarction, unstable angina pectoris with myocardial ischemia, or the need for revascularization procedures).
A daily dosage of 1 gram of EPA and DHA lowers the circulating triglycerides by about 7-10% within 2 to 3 weeks.
- Blood Levels of Long-Chain n–3 Fatty Acids and the Risk of Sudden Death -- 1-Albert et al. NEJM. 2002; 346: 1113-1118) [L]
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