Omega 3s fight high triglycerides!

L’eccesso di trigliceridi nel sangue rappresenta un pericolo per la salute essendo uno dei principali fattori di rischio cardiovascolare, insieme al colesterolo “cattivo”, alla pressione alta, alle cattive abitudini di vita e a particolari patologie o predisposizioni genetiche. Le malattie cardiovascolari, tra cui la malattia coronarica, rappresentano la maggior causa di morte tra adulti di negli anziani, nella maggior parte dei Paesi europei. Ridurre i “trigliceridi alti” è quindi una delle principali armi di prevenzione cardiovascolare e può essere ottenuta non solo grazie ai farmaci ma anche con l’adozione di uno stile di vita sano, in particolare con una alimentazione equilibrata, ad esempio incrementando il consumo di alimenti ricchi di omega 3, cioè pesce e alcuni semi oleosi. È nota infatti da diversi anni l’azione cardioprotettiva degli omega-3, che agiscono con diversi meccanismi sul controllo di colesterolo e trigliceridi alti.

Triglycerides: what are they and what functions do they have?

Triglycerides are found primarily in adipose tissue, in which they are accumulated within specialized cells called adipocytes. Triglycerides can be taken in with food, whether of animal or plant origin, and be formed by the body itself. Chemically they belong to the lipid family, or fats, and are derived from the union of a glycerol molecule with three fatty acids. Fatty acids in turn are differentiated, according to their length and the presence or absence of double bonds, into saturated, monounsaturated and polyunsaturated fatty acids.

Lipoproteins

Like cholesterol, in order for triglycerides to be transported in the blood and reach body tissues, they must bind to particular proteins (Apoproteins), forming structures called lipoproteins. These lipoprotein particles differ in their lipid and protein composition and are classified according to their density inThe triglycerides represent an important energy resource for the human body; in fact, they provide about 9 kcal per gram, compared with 4 Kcal for carbohydrates and proteins. 

• Chylomicrons,
• VLDL (very low density lipoprotein)
• LDL (low density lipoprotein)
• IDL (intermediate density lipoprotein)
• HDL (high-density lipoprotein).

What is the optimal level of triglycerides in the blood? 

The amount of triglycerides in the blood is called triglyceridemia, and it can be detected by a simple blood test performed on an empty stomach. The concentration of triglycerides in the blood is mainly influenced by diet, sex, and age. The normal concentration of triglycerides in the blood is between 60 mg/dl and 150 mg/dl. When the concentration exceeds the latter value, one is in a condition called hypertriglyceridemia, which can be more or less severe:

• Trigliceridi normali:  < 150 mg/dl
• Borderline triglycerides: 150-199 mg/dl
• High triglycerides: 200 to 499 mg/dl
• Very high triglycerides: > 500 mg/dl

The causes of high triglycerides 

Hypertriglyceridemia in most cases, especially when it is between 150 and 199 mg/dl, is due to an incorrect lifestyle, particularly an unbalanced diet and alcohol consumption. In contrast, cases due to genetic disorders, such as familial hypertriglyceridemia, are very rare (about one case in a thousand). In general, the main causes of high blood triglycerides are:

• overweight or obesity
• sedentariness
• cigarette smoke
• poor eating habits
• diabetes mellitus
• alcohol abuse
• kidney disease
• viral hepatitis
• Taking medications (hormonal contraceptives, glucocorticoids)
• genetic factors

Consequences of hypetriglyceridemia

Una concentrazione elevata di trigliceridi nel sangue favorisce l’insorgenza di malattie come la pancreatite e soprattutto disturbi cardiovascolari, quali l’angina, l’aterosclerosi, l’infarto, e l’ictus. In particolare, i trigliceridi alti possono favorire la formazione di placche aterosclerotiche, ossia ispessimenti delle pareti interne delle arterie, che ostacolano il flusso sanguigno causando l’aterosclerosi e altre patologie a carico del cuore e dei vasi sanguigni. Questa relazione è particolarmente valida quando l'ipertrigliceridemia si accompagna ad altri fattori di rischio, come l'aumento del colesterolo LDL (“colesterolo cattivo”) e la riduzione delle HDL (”colesterolo buono”). L'analisi dei trigliceridi ematici viene solitamente accoppiata a quella del colesterolo totale, di quello LDL e di quello HDL, proprio per valutare il rischio cardiovascolare.

How to lower triglycerides?

In addition to reducing or, better yet, eliminating risk factors such as smoking, alcohol and being sedentary, much attention should be paid to diet. In cases of high triglycerides, it is good to: 

• Limit calorie intake by correcting any overweight or obesity
• Reduce consumption of simple sugars (sweets, dehydrated fruits)
• Limit consumption of foods high in saturated fat, such as dairy products and red meat
• Avoid hydrogenated fats, found in snacks and baked goods
• Consume foods rich in antioxidants
• Do not overconsume carbohydrates, which, in excess, are converted into triglycerides and stored in adipose tissue
• Consume polyunsaturated fatty acid peaches, at least 2-3 times a week.
   

There are many studies confirming the beneficial effects of fish intake on fat metabolism and cardiovascular risk(read here). It has been shown that to achieve a 30% reduction in triglyceride concentration, it is necessary to take 120 to 320 grams of fish per day.This action is due to the presence of omega-3 polyunsaturated fatty acids. In fact, it has been widely demonstrated that the intake of omega-3 series fatty acids leads to a significant reduction in the concentration of triglycerides in the blood.

Omega-3 against high triglycerides

The 'interest of the scientific world in omega-3 polyunsaturated fatty acids is due to some epidemiological studies carried out around the mid-1970s. In those very years, it was observed that in the populations of Alaskan Eskimos, Greenlanders (Inuit), and Japanese living in coastal areas, the incidence of ischemia was lower than that observed among Eskimos who had migrated to industrialized countries and that of Japanese living inland. Comparison of mortality between the Greenland Inuit and the Danish population showed that the cardiovascular risk in the former was 10 times lower than that in the latter, and that the Inuit had a diet of fatty fish and 5 times higher in omega-3. Since then, numerous research studies have confirmed the link between omega-3 intake and reduced cardiovascular risk.

But what exactly are omega-3 fatty acids?

As mentioned earlier, omega-3s are polyunsaturated fatty acids, that is, containing a long chain of carbon atoms, held together partly by simple bonds and partly by double bonds. Various types of omega-3 exist in nature, the most important of which are alpha linolenic acid (ALA), eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The latter two are contained in significant amounts in fish species that live in cold seas: salmon, tuna, sardines, anchovies, mackerel, and herring. One ounce of salmon, for example, contains 560 mg of omega-3. The main sources of ALA, on the other hand, are green leafy vegetables such as spinach, legumes, nuts, and vegetable oils such as flaxseed and soybean oil.

L’ALA un acido grasso essenziale, cioè che non può essere sintetizzato dall’organismo ma può essere solo assunto tramite gli alimenti. Esso è il precursore del DHA e dell’EPA, ma nell’uomo gli enzimi necessari a convertire l’acido alfa linoleico negli altri due omega-3, sembrano non essere completamente efficienti, e tale meccanismo viene utilizzato solo in minima parte. Per questo il consumo di alimenti contenenti EPA e DHA tramite l’olio di pesce, è importante per mantenere un livello ottimale delle due molecole.

Ratio of omega-3 to omega-6

The efficiency of conversion of ALA to EPA and DHA is also limited by the presence of high levels of the omega-6 polyunsaturated fatty acids, this is because the enzymes that convert them, "recognize" both omega-3 and omega-6. When the diet is too rich in the latter, the enzymes act on ALA inefficiently, impairing the formation of EPA and DHA. In Western countries this condition is very common, as the ratio of omega-6: omega-3 dietary intake is 15:1. This imbalance is mainly due to the high consumption of foods rich in omega-6, such as seed oil, and the limited consumption of fish, but also to the lower amount of omega-3 in farmed fish compared to caught fish.

The mechanism of action of omega-3 on blood triglycerides

The reduction in triglyceridemia following omega-3 consumption occurs through several mechanisms. EPA and DHA reduce the production of triglyceride-rich lipoproteins (chylomicrons and VLDL) and accelerate their removal. Specifically, at the level of liver cells, omega-3s slow the synthesis of an apolipoprotein, the protein part of VLDL, called ApoB. This results in reduced entry of triglycerides into the bloodstream. The increased removal of triglycerides, on the other hand, is due to the ability of omega-3 to increase the activity an enzyme, called lipoprotein lipase, found in the inner tissue of blood vessels, which promotes the removal of triglycerides from the blood by breaking them down into their individual components (fatty acids and glycerol).

What is the optimal omega-3 consumption to protect heart health?  

In Europe, the new EU Regulation No. 432/2012 of May 16, 2012 states:

• maintenance of normal blood pressure is achievable with a 3 g daily dose of EPA and DHA.
• il mantenimento di concentrazioni di trigliceridi a digiuno è necessario assumere invece 2 g al giorno di EPA e DHA.

In addition, the same regulation states that omega-3s "contribute to normal cardiac function" with an EPA or DHA dosage of 250 mg per day."

Omega-3; better from fish or supplements?

Per essere sicuri di consumare le dosi giornaliere raccomandate di EPA e DHA è necessario consumare dai circa 200 grammi di pesce grasso al giorno tutti i giorni, una condizione non sempre realizzabile. L’elevato consumo di prodotti ittici tra l’altro aumenta la probabilità di assumere i contaminanti in essi contenuti, come ad esempio i metalli pesanti, tra cui il mercurio che è molto pericoloso per la salute. Questo problema può essere evitato assumendo integratori di omega-3 estratti per purificazione da tessuti muscolari di pesce grasso.  L’olio di questi integratori è dunque privo di sostanze dannose.