It is well known that n-3 PUFAs have a dose-dependent lowering effect on serum triglycerides [
22], whose role as cardiovascular disease risk factors has been recently reconsidered [
23]. Other metabolic effects of n-3 PUFAs on lipid profile, related to serum triglycerides reduction, are a small increase of serum high-density lipoprotein (HDL) cholesterol, a significant reduction of post-prandial lipemia and a significant increase in the volume of atherogenic small, dense low-density lipoproteins (LDLs) [
24]. Hypertriglyceridemia, low HDL-C, and small, dense LDL are the atherogenic lipid triad, characterizing the lipid pattern of metabolic syndrome, diabetic dyslipidemia and familial combined hyperlipidemia, all conditions associated with a very high cardiovascular disease risk [
25]. However, n-3 PUFAs have no quantitative effect on the circulating LDL [
26]. Because of their virtual lack of pharmacological interaction and high safety profile, they could have a specific application in the management of hypertriglyceridemia and related dyslipidemias secondary to pharmacological treatments or diseases associated with an adverse metabolic profile. A short list of these conditions is listed below. The use of n-3 PUFAs as therapeutic agents for hypertriglyceridemia in the context of global cardiovascular disease management has recently been evaluated as cost-effective [
27].
Non-alcoholic steatohepatitis (NASH) is a highly prevalent metabolic disorder, characterized by fat infiltration of the liver cells, associated with an increase of cardiovascular disease risk and diabetes, and for which no specific care is currently available [
28]. n-3 PUFA seems to efficiently improve the metabolic pattern and to reduce the liver fat content of NASH patients, both in adults [
29] and in children [
30].
Polycystic ovary syndrome (PCOS) is characterized by relative hyperandrogenism and by an adverse metabolic profile, simulating a metabolic syndrome, usually with hypertriglyceridemia, overweight and impaired fasting glucose. Supplementation with n-3 PUFAs improves the lipid pattern and androgenic profile in PCOS patients [
31].
Chronic kidney disease (CKD) is also a very frequent condition in internal medicine practice. It is associated with premature cardiovascular disease and markedly disturbed lipid metabolism manifesting as elevated triglyceride concentrations, reduced HDL cholesterol concentrations and a preponderance of small, dense LDL particles [
32]. Beyond their known effects on dyslipidemias, n-3 PUFAs could reduce the oxidative stress biomarkers of CKD patients [
33]. Moreover, some trials show that n-3 PUFAs delay the rate of loss of renal function in patients with IgA nephropathy [
34], but also of diabetic nephropathy [
35]. In particular, in IgA nephropathy, n-3 PUFAs potentiate the antiproteinuric effect of angiotensin receptor blockers [
36]. Additionally, studies of omega-3 supplementation in dialysis patients describe salutary effects on triglyceride levels and dialysis access patency [
37]. These effects are also probably dose-related.
Some drugs such as second generation antipsychotics [
38] and highly active antiretroviral therapy (HAART) [
39] are associated with an adverse lipid profile and overall with a phenotypic pattern leading to an increased cardiovascular disease risk. Moreover, they often have a high risk of pharmacological interaction with lipid-lowering drugs. In these patients, n-3 PUFAs could contribute to better control of the lipid profile and to a useful anti-inflammatory reaction [
40].
In antipsychotic treated patients n-3 PUFAs have the potential to improve the lipid pattern and the drug-related arrhythmia risk [
41], but also to reduce some psychosis related symptoms [
42]. The n-3 PUFA supplementation in HIV patients treated with HAART is associated with a significant improvement in dyslipidemia and biomarkers of systemic inflammation level, without significant change in renal and liver enzymes [
43].
The main limitation of the above listed effects is the lack of large clinical trials demonstrating the effect of n-3 PUFAs on the long-term cardiovascular prognosis of these patients.