Knowledge Biological Roles Fish Oil Supplements Widely Known Biology Essay


Public interest in healthy living is increasing across the world, sparking a huge demand for the supplements market. However knowledge of biological roles of fish oil supplements is not widely known and so cheaper and lower quality made supplements which otherwise seem 'value for money' are unlikely to offer health benefits that combat many risk-factors of modern day diseases or deficiencies as would those supplements that have been molecularly distilled to extract impurities and maximise concentrations of the eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) (Bailey, 2009). Another important factor to highlight is that omega-6 fatty acids work in combination with omega-3 fatty acids and this balance also needs to be maintained. This study is about highlighting the risk-factors of fish-derived supplementation and what dosages are best to help fight pathological diseases of the cardiovascular, immune and neurological systems, and if these levels are in all fish oil supplements that are currently on the market or is the use of these fish oil supplements overrated and of little effect, evaluation of the products on the market will be reviewed and compared to known scientific benefits of taking the natural fish oils in a diet.

Literature review:


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The human body makes use of carbohydrates, fats, proteins and fatty acids as major dietary constituents they all serve together with hormones to regulate gene expression in response to food intake and nutritional changes (Surette 2008). Regulation of this allows the body to make use of several metabolic pathways and mechanisms that control fuel utilisation according to the availability of lipid and glucose and that govern the inter-conversion, transport, storage, and mobilisation (Simopoulos, 1999). Together these mechanisms ensure a healthy energy homeostasis; any alteration in this balance can lead to promoting, obesity, hyperlipidemia, diabetes, cardiovascular disease, cancer, inflammation and autoimmune disease (Simopoulos, 1999). Hence it is vital that the human body has all its nutrients and metabolites to maintain optimum functionality.

Objective of this study

The objective of this paper is to carry out an investigation that will look at the advantages and disadvantages of fish oil supplements with a view of determining if fish oil supplements are really needed or do not really make a difference to a persons diet. Taking into consideration the following aspects; fish oils need to be balanced out with vitamin E intake (Muggli, 1989) the levels of which are yet to be determined because fish oil supplement intake alone can induce a vitamin E deficiency and the importance of ingesting eicosapentaenoic acid (EPA) in purified form (Meydani et al 1990). Unless supplements have stated that they contain pure EPA their purity is questionable with regards to containing potentially toxic compounds. The side effects of fish oil supplements will be evaluated and which dosages are tolerable, along side this what levels of vitamin A and D should be associated with fish oil supplement intake. Lastly fish oil supplements have been helpful in a variety of diseases, including bipolar disorder and depression, and its use in these areas will be considered (Simopoulos, 1999; Schachter et al 2005).

Importance of this research

There is a great deal of interest in 'health supplements' as the world is becoming more 'health conscious' and peoples diets are often lacking in essential vitamins and nutrients and therefore it is vital to evaluate supplements for their usefulness. The aim of this paper is to evaluate data to answer the following question 'are fish oils overrated?' by looking at the potential harmful effects and weighing them out against the benefits (see methodology section).


The expected outcome of this research is; fish oil supplement are not overrated for use in Western staple diets. However compliance is a problem because it not widely stated what dosages of fish oil supplements are needed and in what form (oil or capsule) or of what purity. Another problem is the intake of environmental contaminants such as methyl mercury and organochlorides associated with supplements derived from fish (Maycock and Benford, 2007), as well as fatty fish consumption, which is hypothesised that un-purified fish oil supplements could be harmful.

Chemical and Biological Effect of Omega-3 and Omega-6 Fatty acids

At least 20 different types of fatty acids are consumed by humans these are classified as saturated, monounsaturated and polyunsaturated (Schachter et al 2005). Omega-3 and omega-6 are both classed as essential fatty acids that are both polyunsaturated fatty acids (PUFA). Omega-3 (-3 or n3) in nutrition gives the following three essential types of fatty acids; -linolenic acid (ALA; 18:3n23) eicosapentaenoic acid (EPA; 20:5n3) and docosahexaenoic acid (DHA; 22:6n3) and consist of 3, 5, or 6 double bonds in a carbon chain of C20 with a cis-configuration, fragility is higher for -3 fatty acids due it last double bond being more geometrically and electrically more exposed (Lee and Lip 2003). Linoleic acid (LA; 18:2n26) is one of the -6 fatty acids and is a short-chained molecule, another is arachidonic acid (AA; 20:4n6) this is a physiologically significant fatty acid and is the precursor for prostaglandins and other physiologically and immunologically active molecules (Schachter et al 2005). Both ALA and LA are not synthesized by the body; they need to be ingested via dietary constituents. ALA and LA are converted into long-chain PUFAs in the liver, and hence increasing the number of C atoms and double bonds (Lee and Lip 2003).

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Fatty acids have many fates in the body, including β-oxidation for energy, storage in deposit fat or incorporation into phospholipids, which form the major structural components of all cellular membranes (Schacky et al, 1985; Sargent et al, 1999). Sources of -3 and -6 fatty acids are fish such as tuna, trout and salmon which are especially rich in -3 fatty acids. Fish-oil supplements are also a rich source, as they typically contain 30%-50% omega-3 fatty acids (Surette 2008). -3 Fatty acids; EPA and DHA are predominantly found in marine fish (Schacky et al, 1985) and fish oil supplements. ALA is a plant derived -3 FA and an important precursor to EPA and DHA. Figure 1 illustrates the metabolic effect of -3 and -6 PUFA from dietary sources.

Conversion of dietary ALA into EPA, DHA and docosapentaenoic acids (DPA) is not efficient in people who consume a typical Western diet (Taber et al 1998). Northern American diets comprise of mainly of -6 fatty acids; 89 per cent of LA PUFAs makes up the bulk consumption whereas only 9 per cent is ALA PUFA consumed (USDA 1995).

Figure 1: Metabolic effect -3 and -6 PUFA from dietary sources

(Bailey, 2009)

Effects of Fish Oil by dietary consumption

Simpolous (2002, 2006) has extensively studied ratios of -6/-3 FA among pre-agricultural humans and agricultural man. It was found that western diets were consuming larger amounts of -6 than -3 fatty acids, the ratio which was supposed to be that of approximately 1 was found in western diets to be 15:1 and 16.7:1. His studies also documented that many of the pathological diseases such as cardiovascular disease, diabetes, cancer obesity asthma depression were all associated with increased production of thromoboxane A2 (TXA2), leukotriene, interleukins (IL-1β, IL-6), tumour-necrosis factor and C-reactive proteins, these high levels were due to increased consumption of -6 FA and less of -3 FA (Simpolous 2002; 2006).

It has been well documented that Greenland Eskimos had a higher mortality rate due to coronary heart disease and low inflammatory joint diseases compared to the Danes (Webb, 2002). Eskimos diet has been high in fish and marine organisms such as whale meat and seal. Dyberg et al (1975) carried out an extensive study to compare both countries dietary intake it was found that Greenland Eskimos consumed more sea meat hence their protein intake was 2½ times more than that of Danes.

Many literature papers have documented that a higher intake -3 fatty acids is considered more desirable than that of consuming -6 fatty acids alone however in practice recommended levels have been difficult to achieve mainly because our dietary habits are dependent on our lifestyle and rarely easy to change. Some research shows that fish oil supplements are an effective way of overcoming the loss of essential fatty acids (Bailey, 2009).

Fish Oil Supplement Effects

The effect of dietary manipulation and the metabolism PUFA has been greatly studied to distinguish influencing factors that enhance physiological responses mediated by the oxygenated metabolites of the eicosapolyenoic acid cascade (El Boustani et al 1987).

Triglyceride levels have been lowered by supplementation trials using purified EPA (Rambjor et al 1996) and the effects of EPA and DHA on lipoprotein metabolism have been studied in cultured cells of animal models (Kobatake et al 1984 and Demoz et al 1992).

Fish oil supplement consumption has been found to induce a vitamin E deficiency, this may be due to -3 inducing a peroxidation effect of cellular membranes, resulting in a higher need for vitamin E (membrane antioxidant) (Meydani et al 1990 ). Animal models have been used to document the induction of vitamin E deficiency by consuming fish oil supplements (MacKenzie et al, 1941) and the ultimate damage to tissues caused by the oxidation plays an important role in the pathology of atherosclerosis, emphysema, stroke and cancer (Halliwell, 1978).

Common side effects of fish oil supplements include flatulence, heartburn, halitosis, belching, and diarrhoea (Appel et al, 1993; O'Connor et al, 1992; Donnelly et al, 1992) and so are discouraged from use, meanwhile trials using fish oils for diseases such as Crohn's disease have also been carried out (Belluzi et al, 1996). However recent a study shows that using an enteric-coated preparation of fish oil allowed the fatty acids to become incorporated into the phospholipid membrane exerting the desired effect to keep patients in remission with reduced gastric side effects (Belluzi et al, 1996).

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Another important factor to look at when discussing fish oil supplements is the content and purity of fatty acid the individual is being administered, as cheaper fish oil supplements do not necessarily provide effective protection from disposition to disease. Scientific papers that have been studied have also shown that they rarely use market based fish oil supplements but have used either fatty acid esters only and all their recommended dosing levels are variable by greater extent for different diseases e.g. 1-1.5g of long-chain -3 PUFA is recommended to reduce cardiovascular risk factors., whereas as much as 2-4g is needed to treat hypertriglycerdaemia (Geleijnse et al, 2002; Hornstra, 2001).

Another important factor to consider in recognising importance of fish oil supplement intake and increasing or introducing oily fish into the diets is that Greenland Eskimos did not need to consider pollution of their waters and hence their staple diet was fish even for pregnant women. However for industrialised countries pregnant women may not be able to adhere to Eskimos diets as fish and fish liver oil supplement can be contaminated with pollutants also there is a higher risk of overdosing of vitamin A and D.

Clinical Trials

In 1989 Burr et al conducted a randomised controlled trial to in order to scientifically evaluate the effect of diet on the secondary prevention of myocardial infarction in men below the age of 70 and incorporated 2033 subjects calling it The Diet and Reinfarction Trial (DART). The investigation entailed of three dietary factors: (1) reducing total fat and an increase increasing PUFA intake, (2) increasing fatty fish intake and (3) increasing cereal fibre intake. Cereal intake was recorded due to omega-6 fatty acid - LA is abundantly found in vegetable oils, bread and snack food (Ratnayke et al 1993). DART studies revealed lowering mortality rate. Animal studies conducted by McLennan et al 1990 and Charnock 1991 showed that -3 PUFA - EPA and DHA were responsible for preventing ventricular fibrillation in acute-ischemic patients and in-vitro studies have showed an anti-arrhythmic effect (Leaf et al. 2003) this is most likely to have explained DART lowered mortality rate following the initial stage of MI whereas without an anti-arrhythmic effect fatal arrhythmia could have ensued (Burr 2007). Burr et al 1989 conducted the largest of dietary studies in its time compared to those that involved only 500 subjects which scarcely resulted in equivocal findings (Rose et al 1965; MRCRC, 1968; Leren, 1970; Woodhill 1978). Hence the DART study opened a new chapter in lowering morbidity and mortality in myocardial infarct patients hence encouraging studies to be conducted to counteract other diseases.

Other trials similar to that of DART have also been practiced these are; GISSI- Prevenzione trial (GISSI-Prevenzione Investigators, 1999), the results of which were similar to that of DART showing a reduction in mortality including risk-factors of cardiovascular problems following those patients that has survived an initial MI attack. The different factor associated with this investigation was the use of vitamin E (-tocopherol) alone (without any PUFA intake) no benefit was observed.

Another trail conducted was that for the Lyon Diet Heart Study (de Lorgeril et al 1999) again this was a randomized study. Subject patients were mainly Italian, and many already consumed a Mediterranean diet bread, fruit and vegetables, more fish, less meat higher consumption of olive oil (de Lorgeril et al 1997). In both studies the reduction in mortality was less than that observed for DART possibly due to their consumption of an already proposed higher PUFA diet.

Research methods

The method is set out according to the objectives and will be based on collecting qualitative data from studies that have used fish oil supplements, esters or ethyl esters of omega-3 and omega-6 fatty acids to decrease the effects of disease and a quantitative data set will be complied of commercial brands i.e. Sevens Seas Oil including its components and prescribed dosages. Scientific papers will be studied to evaluate these findings.

The following questions will be answered by discussing the following topics:

What level of vitamin E needs to be taken and in what form as to avoid inducing a deficiency to it?

What dosage of EPA and DHA are better at preventing disease?

What side effects of fish oil supplements are likely to occur and at which dosages are they tolerable?

What levels of vitamin A and D are associated with fish oil supplements?

Another important factor that will be extensively researched is clinical trials such as bipolar disorder and depression, cardiovascular disease, auto immune, inflammatory joint disease i.e. arthritis, Crohn's Disease. Studies will incorporate data of sexes, various age groups and implication in pregnancies and infants.

Expected time line for the work to be carried out

The duration in which this research is expected to be carried out and completed is asset out below:

Complete proposal 10 May 2009

Complete literature evaluations by 30 June 2009

Complete analysis of information by 20 July 2009

Have presentation ready by 31 July 2009