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Keywords:

  • n-3 fatty acids;
  • eicosapentaenoic acid;
  • docosahexaenoic acid;
  • fish oil;
  • functional foods

Abstract

  1. Top of page
  2. Abstract
  3. Introduction
  4. Dietary Intakes and Recommendations for Long Chain n-3PUFA
  5. Health Benefits and Mechanisms of Action of n-3PUFA
  6. Food Sources of n-3PUFA
  7. Facts about Foods Fortified with Long Chain n-3PUFA
  8. Conclusions
  9. Research Needs
  10. References

ABSTRACT:  n-3 Polyunsaturated fatty acids (n-3PUFA) of marine origin have been shown to be essential for brain development and cognitive function. In addition to their essentiality, the scientific literature is full of evidence to suggest that regular consumption and/or dietary supplementation with long chain n-3PUFA give several health benefits including: prevention of cardiovascular diseases, inflammatory diseases, dyslexia, and depression. Long chain n-3PUFA intake in the Western countries, including Australia, has been shown to be inadequate. This is largely due to the fact that the Western populations do not eat seafood on a regular basis because of its cost and availability, and many individuals do not like the flavor/taste/odor of seafood. Foods fortified with long chain n-3PUFA could play an important role in meeting the demands for optimal health. Marine n-3PUFA are not likely to compete with saturated, monounsaturated, and n-6PUFA as a major source of dietary fat; however, increasing the intake of foods containing marine n-3PUFA is an important strategy for the prevention of chronic illnesses. Recent developments in food technology allow fortification of foods, such as bread, dairy products, eggs, pasta, biscuits, margarines, and other spreads, without the undesirable fish odor/taste and with reasonable shelf life. There is a need to increase the amount of long chain n-3PUFA consumed per serve and optimize their bioavailability. This article reviews the foods fortified with marine n-3PUFA and their role in meeting daily requirements, and highlights the need for further research in this important area of functional foods.


Introduction

  1. Top of page
  2. Abstract
  3. Introduction
  4. Dietary Intakes and Recommendations for Long Chain n-3PUFA
  5. Health Benefits and Mechanisms of Action of n-3PUFA
  6. Food Sources of n-3PUFA
  7. Facts about Foods Fortified with Long Chain n-3PUFA
  8. Conclusions
  9. Research Needs
  10. References

The human diet contains polyunsaturated fatty acids (PUFA) belonging to the n-6 and n-3 fatty acid families. Major dietary n-6PUFA include linoleic (18:2), γ-linolenic (18:3), and arachidonic (20:4) acids, whereas major dietary n-3PUFA include α-linolenic (18:3), eicosapentaenoic (20:5), docosapentaenoic (22:5), and docosahexaenoic (22:6) acids. Linoleic, γ-linolenic, and α-linolenic acids are present in large quantities in foods of plant origin, such as corn or maize oil, sunflower seed oil, cottonseed oil, soybean oil, linseed oil, evening primrose oil, and canola oil. Arachidonic acid originates from muscle and organ meats, or alternatively may be synthesized within the body via successive desaturation and chain elongation of linoleic acid. The longer chain n-3PUFA are found mainly in foods of marine origin or are synthesized via desaturation and chain elongation of α-linolenic acid within the human body. Recent evidence suggests that lean meat contributes significantly to the longer chain n-3PUFA content of the Western diet (Sinclair and others 1982; Meyer and others 2003; Li and others 2005). When present in equimolar concentration, linoleic acid and α-linolenic acid compete for conversion to their respective longer chain products, arachidonic acid and eicosapentaenoic acid (Contreras and Rapoport 2002). Recent studies have demonstrated that, for maximum conversion of α-linolenic acid to eicosapentaenoic acid and a maximum reduction in the formation of arachidonic acid, the α-linolenic acid should be supplemented with saturated fatty acids (SFA) rather than n-6PUFA (Garg and others 1989; MacDonald-Wicks and Garg 2004).

Saturated, monounsaturated, and n-6PUFA will continue to form a majority of the fatty acids present in the human diet. n-3PUFA, particularly the longer chain fatty acids of marine origin, constitute a small proportion of the total fat intake. For individuals or populations who consume no seafood or muscle or organ meats, such as vegetarians, α-linolenic acid is the only potential source of n-3PUFA. However, recent studies have demonstrated that the extent of conversion of α-linolenic acid to longer chain n-3PUFA is modest, and it is uncertain as to whether meaningful amounts of conversion occur to support normal growth and development. Emken and others (1994) found 15% conversion, whereas Pawlosky and others (2001) reported 0.2% conversion; both reported that the conversion to docosahexaenoic acid was much less than that to eicosapentaenoic acid and docosapentaenoic acid. However, the longer chain n-3PUFA that accumulates in tissue membranes is docosahexaenoic acid. Therefore, in some individuals, supplementation of the diet using fish oil capsules or foods fortified with fish oil fatty acids may be the only option to supply the recommended levels of longer chain n-3PUFA. As the dose of marine n-3PUFA required to achieve targeted health benefits is much higher than the recommended levels for maintenance of general health, it becomes even more challenging to meet the required amount of these fatty acids in order to minimize the risk of chronic disease.

Dietary Intakes and Recommendations for Long Chain n-3PUFA

  1. Top of page
  2. Abstract
  3. Introduction
  4. Dietary Intakes and Recommendations for Long Chain n-3PUFA
  5. Health Benefits and Mechanisms of Action of n-3PUFA
  6. Food Sources of n-3PUFA
  7. Facts about Foods Fortified with Long Chain n-3PUFA
  8. Conclusions
  9. Research Needs
  10. References

The dietary intake of total n-3PUFA has been estimated from a large dietary survey in the United Kingdom to be 2000 mg for men and 1410 mg for women (Gregory and others 1990), but these estimates do not distinguish between plant and marine n-3PUFA. In the United States, the dietary intake of total n-3PUFA has been reported to be 1600 mg/d, of which 100 to 200 mg/d is 20:5n-3 and 22:6n-3 (Kris-Etherton and others 2000). A recent study reported an average daily intake of 189 mg of marine n-3PUFA (20:5, 22:5, and 22:6 at 56, 26, and 106 mg/d, respectively) (Meyer and others 2003) in the diets of Australians. The major food sources contributing to n-3PUFA intakes include seafoods (71%), meats (20%), and eggs (6%). This study indicated that Australians are failing to meet the recommendations as outlined in the draft document of the new Australian Nutrient Reference Values (previously known as Recommended Dietary Intakes) in which adequate intake has been set at 190 mg/d. The paper also highlighted the need for strategies to increase the availability and consumption of foods enriched with long chain n-3PUFA. In contrast to these Western diets, Japanese eat about 80 g of fish and shellfish per day, providing approximately 1000 to 2000 mg/d of 20:5n-3 and 22:6n-3 (Sugano and Hirahara 2000). This high fish consumption is believed to contribute to the reduced incidence of coronary heart disease (CHD) in this population (Lands and others 1990).

A host of health agencies and professional organizations worldwide have issued recommendations on the intake of long chain n-3PUFA (Table 1). A number of recommendations to increase marine oil intake in people with or at risk of cardiovascular disease (CVD) have been made. These recommendations are based on evidence derived from sound clinical trials linking dietary deficiency of long chain n-3PUFA with cardiovascular events, and a recent meta-analysis of 13 cohort studies including more than 220,000 individuals followed for CHD mortality rates for an average of 12 y (He and others 2004). The British Nutrition Foundation Task Force recommends a daily intake of 500 to 1000 mg/d of long chain n-3PUFA, which is equivalent to 1 to 2 portions of oily fish per week (British Nutrition Foundation 1992). In contrast, the U.K. Department of Health recommends a daily intake of 200 mg of 20:5n-3 and 22:6n-3 (Department of Health 1994). Sweden recommends that the ratio of n-6PUFA to n-3PUFA be 5:1 (Nordic Working Group on Diet and Nutrition 1996). The World Health Organization recommends 1 to 2 servings of fish per week, each containing 200 to 500 mg of 20:5n-3 and 22:6n-3 (Kris-Etherton and others 2002). The American Heart Association (AHA) recommends that people with no CVD should eat oily fish twice/week and foods rich in α-linolenic acid (walnuts, canola, soy, and flaxseed). However, those with documented CVD should eat approximately 1 g of 20:5n-3 and 22:6n-3 per day, preferably from oily fish but also in supplement form. The AHA further recommends that, for triglyceride-lowering effects, 2 to 4 g of n-3PUFA should be consumed per day as a supplement under a physician's care (Kris-Etherton and others 2003). The International Society for the Study of Fatty Acids and Lipids (ISSFAL) recommends adequate 18:2n-6 intake as 2% energy, healthy 18:3n-3 intake as 0.7% energy, and, for cardiovascular health, a minimum of 500 mg of 20:5n-3 and 22:6n-3 per day (ISSFAL 2004). The expert panel supported by the National Institutes of Health recommends 300 mg of docosahexaenoic acid per day for pregnant or lactating females (Simopoulos and others 1999). The Joint FAO/WHO Expert Consultation on Fats and Oils in Human Nutrition made no specific recommendations for n-3PUFA, but recommended that individuals with linoleic-to-linolenic acid ratio in excess of 10:1 should be encouraged to consume foods rich in n-3PUFA, such as green leafy vegetables, legumes, fish, and other seafood (FAO/WHO Consultation on Fats and Oils 1994).

Table 1—.  Recommended Daily Intake of Long Chain n-3 Polyunsaturated Fatty Acids
OrganizationRecommended daily dose of 20:5n-3 plus 22:6n-3 (mg)Population
National Health and Medical Research Council (Australian Nutrient Reference Values)190General population
British Nutrition Foundation Task Force500–1000People at risk of CVD
U.K. Department of Health200General population
European Academy of Nutritional Science200General population
ISSFAL650General population
AHA1000People at risk of CVD
Oily fish (twice/week)General population
>3 g/dTo reduce triglyceride levels
NIH300Pregnant and lactating females

In summary, dietary recommendations for long chain n-3PUFA supplementation are still a matter of debate. Recommendations vary depending on desired disease prevention: daily ranges for 20:5n-3 and 22:6n-3 begin at 180 mg (for healthy adults) to 500 mg (decrease in heart disease) to 1000 mg (decrease in mental illness) (Ruxton and others 2004).

It is also recommended that the ratio of n-6PUFA to n-3PUFA should not exceed 4 to 1 in order to optimize the bioavailability, metabolism, and incorporation into membrane phospholipids (Garg and others 1988c, 1990; Volker and Garg 1996). There are three possible ways to achieve this: (1) simply increasing long chain n-3PUFA consumption in the diet; (2) keeping the SFA, monounsaturated fatty acids (MUFA), and long chain n-3PUFA content constant and decreasing n-6PUFA in the diet (however, taking a whole-diet approach and in the light of general dietary advice to decrease the proportion of SFA in the diet, to concomitantly decrease n-6PUFA will encourage a low-fat intake which has the potential to reduce the level of circulating high density lipoprotein (HDL) cholesterol (Katan 1998; Terpstra and others 2000)); (3) maintaining the level of long chain n-3PUFA, decreasing total n-6PUFA and making up the shortfall in dietary fat intake with MUFA and/or SFA (this will improve the n-6PUFA-to-n-3PUFA ratio without reducing the fat content in the diet and will therefore avoid the detrimental effects of a reduction in circulating HDL cholesterol level). Whether either of the last two options is suitable to optimize the n-6PUFA-to-n-3PUFA ratio without adverse effects on the plasma lipid profile remains to be established.

Health Benefits and Mechanisms of Action of n-3PUFA

  1. Top of page
  2. Abstract
  3. Introduction
  4. Dietary Intakes and Recommendations for Long Chain n-3PUFA
  5. Health Benefits and Mechanisms of Action of n-3PUFA
  6. Food Sources of n-3PUFA
  7. Facts about Foods Fortified with Long Chain n-3PUFA
  8. Conclusions
  9. Research Needs
  10. References

Epidemiological and experimental evidence suggests that consumption of marine n-3PUFA is associated with a reduced risk of CVD, certain types of cancer, inflammatory disease (rheumatoid arthritis, asthma, lupus, and ulcerative colitis), diabetes mellitus, multiple sclerosis, and clinical depression (Ruxton 2004; Wang and others 2004). It is noteworthy that, if the population under study already has a high overall intake of fish, eating more fish is not associated with increased health benefits. These effects are mediated by alterations in circulating lipid levels, eicosanoids, cytokines, and physico-chemical properties of the cellular membranes. n-3PUFA are pleiotropic molecules with a broad variety of different biological actions, including hypotriglyceridemic, anti-aggregatory, anti-inflammatory, and anti-arrhythmic responses. Long chain n-3PUFA have been shown to reduce the size of the chylomicrons synthesized in the intestinal mucosa and released into the thoracic lymph following consumption of foods containing fats (Chan and others 2003). They have also been shown to reduce circulating levels of triglyceride and to reduce secretion of very low density lipoprotein (LDL) from the hepatic tissue (Parks and others 1990; Ikeda and others 2001). Dietary supplementation with long chain n-3PUFA has been shown to inhibit delta-6 desaturase activity, and reduce plasma and tissue levels of arachidonic acid (20:4n-6) (Garg and others 1988a, 1988b). Dietary 20:5n-3 and 22:6n-3 have also been shown to compete at the cyclo-oxygenase and lipo-oxygenase levels with 20:4n-6 to reduce the formation of series-2 eicosanoids (von Schacky and others 1985; Kurlandsky and others 1994; Nordoy and others 1994). Consumption of long chain n-3PUFA has also been associated with a reduction in plasma levels of pro-inflammatory cytokines (interleukins and tumor necrosis factor) (Endres and others 1994; Wallace and others 1995; Wachtler and others 1997; Seljeflot and others 1999). Dietary supplementation with fish oil high in long chain n-3PUFA is accompanied by a reduction in fibrinogen content and down regulation of the expression of adhesion molecules such as VCAM-I and ICAM-I (Gans and others 1988; Collie-Duguid and Wahle 1996; Hughes and others 1996; Vanschoonbeek and others 2004). Dietary long chain n-3PUFA are incorporated into the platelet phospholipids and concomitantly reduce platelet aggregation (Skeaff and Holub 1988; Chen and others 2000). Recent studies have demonstrated that dietary supplementation with long chain n-3PUFA improves vascular compliance and favorably modifies blood pressure (Cobiac and others 1992; Appel and others 1993; McVeigh and others 1994; Geleijnse and others 2002). Incorporation of long chain n-3PUFA into the membrane phospholipids can alter the physico-chemical properties of the membrane and influence membrane-associated functions, such as hormone binding, ion channels, enzyme activities, and so on. (Clandinin and others 1991).

The U.S. Food & Drug Administration has granted a qualified health claim for dietary n-3PUFA supplements: “Consumption of Omega-3 fatty acids may reduce the risk of CHD. FDA evaluated the data and determined that, although there is scientific evidence supporting the claim, the evidence is not conclusive” (US Food & Drug Administration 2004). The United Kingdom has become the first country outside the United States to grant an n-3 fish-oil health claim that manufacturers throughout Europe have begun applying to their products. The claim, issued by the Joint Health Claims Initiative, made up of consumer protection groups, food law enforcers, and members of the food industry, states: “Eating 3 g weekly, or 0.45 g daily, long chain n-3PUFA, as part of a healthy lifestyle, helps maintain heart health.” (Joint Health Claims Initiative 2005).

Given that most Western populations fall well short of recommended oily fish servings per week, food formulators are working hard to develop other ways of increasing fish oil intake, and a wide range of products including eggs, breads, crackers, milks, cheeses, and juices are expected to carry the claim in the near future. Apart from well-informed health seekers, the majority of the consumers in Australia and New Zealand display poor understanding of omega-3 fatty acid types and sources (Patch and others 2005a, 2005b). Moreover, for a vast majority of consumers, improved heart health remains the health benefit most readily linked with n-3PUFA intake/supplementation.

Safety concerns relating almost exclusively to the administration of large doses of LCn-3PUFA have been expressed by some experts. Subjects reported a higher incidence of belching and unpleasant taste (Belluzzi and others 1994) when taking fish oil capsules as supplements, but not experienced by those who increased their n-3PUFA intake purely by dietary means. Since LCn-3PUFA are known to exert a dose-related increase in bleeding time, concerns have been raised about the possibility of increase in blood loss during labor or during surgical operations. However, there are no documented cases of abnormal bleeding even when high dosages of LCn-3PUFA were supplemented along with anticoagulant medications. High doses of LCn-3PUFA have the potential to increase LDL cholesterol levels and/or increase oxidizability of LDLs; however, clear evidence and clinical relevance of these findings remain unclear. People who bruise easily, have a bleeding disorder, or take blood thinning medications are advised to take LCn-3 supplements under the supervision of a healthcare provider.

Food Sources of n-3PUFA

  1. Top of page
  2. Abstract
  3. Introduction
  4. Dietary Intakes and Recommendations for Long Chain n-3PUFA
  5. Health Benefits and Mechanisms of Action of n-3PUFA
  6. Food Sources of n-3PUFA
  7. Facts about Foods Fortified with Long Chain n-3PUFA
  8. Conclusions
  9. Research Needs
  10. References

Common plant sources of n-3PUFA (in the form of α-linolenic acid) include canola oil, soybean oil, walnuts, and flaxseed (linseed) oil. However, plant biologists are removing α-linolenic acid from these sources by genetic manipulation and/or by chemical hydrogenation to improve the shelf-life stability and cooking qualities (Robert and others 2005). Enriched eggs, produced by the addition of fish meal or canola/linseed oil to chicken feed, are also a good source of long chain n-3PUFA (Scheideler and others 1997; Smuts and others 2003; Bourre 2005a). However, concerns with cholesterol present in yolk prohibit frequent consumption of eggs. It is also possible to enrich poultry and pig meat with long chain n-3PUFA by supplementing the feed with fish meal or canola/linseed oil (Metcalf and others 2003; Bourre 2005b). Food sources of long chain n-3PUFA (20:5n-3 and 22:6n-3) include seafoods, fish oils such as cod liver oil, menhaden oil, and herring oil, lipid extracts from fungi, and algae of marine origin. With increased consumption of seafood and impure marine oils, concerns have been raised about the toxins, such as parachlorobenzoic acid, DDT, dioxin, and methyl mercury, that may be present in these foods (Mahaffey 2004; Melanson and others 2005).

Regardless of the source, all long chain n-3PUFA are highly susceptible to oxidation, which leads to unpleasant off-flavors and taste in the final product (Nawar 1996; Watkins and German 1998). The oxidative instability of long chain n-3PUFA is markedly higher than that of oleic acid (18:1n-7) and linoleic acid (18:2n-6). Exposure to high temperatures and air during processing and storage can cause rapid deterioration of these fatty acids. Another problem is the residual “fish” aroma and taste that often remain in the product even if n-3 oils are properly processed and stored. These problems can often be minimized by refining and deodorizing the oil, and packaging in an inert gas like nitrogen to prevent oxidation. Natural and synthetic antioxidants such as tocopherols and ascorbyl palmitate are commonly used to help prevent oil oxidation (Frankel and others 1994; Huang and others 1994; Chen and Ho 1997). However, the effectiveness of antioxidants depends on several factors, such as pH, temperature, polarity and concentration of antioxidants, and the physical properties of the food system. Consequently, great variations can be seen in different food systems.

Microencapsulation of oil can be used to delay or inhibit oxidation and allow the manufacturer to handle and incorporate oil in food products (Kolanowski and others 1999; Klinkesorn and others 2005). The microencapsulation process can also help mask undesirable fishy odors and flavors in the final product. A number of companies, including BASF, Roche, Clover, and Ocean Nutrition, manufacture and sell microencapsulated fish oil powders for use in food products (Table 2). Moreover, several patents on microencapsulation technologies for the protection and encapsulation of fish oil exist. Most of these encapsulated n-3 oil products are based on the formation of fish oil emulsions using proteins, polysaccharides, lecithin, and other low molecular weight emulsifiers, individually and in various combinations. The emulsions are then spray-dried to form microcapsules. However, the amount of oil that can be delivered in these formats varies from 1% to 30%. During spray-drying, a significant proportion of the oil can migrate into the surface of the powder particle, which readily oxidizes and can cause off-flavors in food products. To improve the oxidative stability of the microencapsulated product, antioxidants can be added to either the oil or the powder, or both. Microemulsification has added advantages, such as long shelf life, masking of the taste and flavor of fish, and improved bioavailability of the n-3PUFA. However, particular attention needs to be paid to the material used for microencapsulation for maximum bioavailability. These technologies have allowed the fortification of frequently consumed foods, such as breads, biscuits, soups, fruit juices, and spreads with reasonable consumer acceptability. However, the levels of incorporation that can be achieved with existing technologies are very low and the amounts of long chain n-3PUFA required to meet recommended allowances are impractical in most cases. Further work in this area needs to concentrate on the development of convenience foods, suitable for fortifying with larger amounts of n-3PUFA per serve, in a palatable format.

Table 2—.  Examples of Some Commercially Available Microencapsulated n-3 Powder Products
Company/ProductProduct descriptionIngredients
BASF/Dry n-3 18:12Microencapsulated fish oil rich in EPA and DHA, light yellowGelatin and sucrose matrix, coated in starch, sodium ascorbate (E310), ascorbic acid (E300), tocopherol (E306), tricalcium phosphate (E341)
BASF/Dry n-3 5:25CMicroencapsulated fish oil high in DHA, light yellowCaseinate and sucrose matrix, coated in starch, ascorbyl palmitate (E304), sodium ascorbate
Nu-Mega/Driphorm Hi-DHA 50Powder containing 48% Hi DHA tuna oil, bland tasteTuna oil, sodium caseinate, dextrose monohydrate, dried glucose syrup, sodium ascorbate (E301), mixed natural tocopherols, lecithin, dl-alpha tocopherol (E307), ascorbyl palmitate (E304)
Salkat/Vana Sana EPA/DH, A Rich Powder, 50A 070Powder, typical tasteNatural fish oil concentrate, carbohydrates, antioxidants, free flowing agent

Facts about Foods Fortified with Long Chain n-3PUFA

  1. Top of page
  2. Abstract
  3. Introduction
  4. Dietary Intakes and Recommendations for Long Chain n-3PUFA
  5. Health Benefits and Mechanisms of Action of n-3PUFA
  6. Food Sources of n-3PUFA
  7. Facts about Foods Fortified with Long Chain n-3PUFA
  8. Conclusions
  9. Research Needs
  10. References

There is a constantly growing range of foods enriched in n-3PUFA available to the consumer (Table 3). One of the limitations of currently available foods fortified with long chain n-3PUFA is that they need to be consumed in large quantities to meet a dietary recommendation of 200 mg/d for healthy adults, or even in larger amounts to meet a dietary recommendation of 1000 mg/d of long chain n-3PUFA for people at high risk of CVD. Australian food examples include:

Table 3—.  Examples of Some Commercially Available Foods Fortified with n-3 Polyunsaturated Fatty Acids
Product20:5n-3/22:6n-3% of daily dose (general population)% of daily dose (for those at high risk of CVD)Country
Dairy Farmers (Farmers Best) milk31.2 mg per 250 mL serve 15 3Australia
Brownes (Heart Plus) milk150 mg per 250 mL serve 7515Australia
Coles (High Top) bread37 mg per serve of 2 slices 16   3.2Australia
AP Foods (Seachange) omega-3 spread200 mg per 35 g serve10020Australia
Fish oil capsules (most brands)300 mg per 1 g capsule15030Australia
Cereal bars (Biomedical Laboratories)150 mg per bar 7515United Kingdom
  • • 
    Dairy Farmers (Farmers Best) milk provides at most 31.2 mg of 20:5n-3 and 22:6n-3 per 250 mL serving, which is no more than 15% of what is needed per day to benefit heart health, and less than 3% of the recommended dose for people at high risk of CVD.
  • • 
    Brownes (Heart Plus) milk drink has been specially formulated to improve the performance of the heart and cardiovascular system as part of a balanced diet with regular physical activity. This product does better. One serve (250 mL) contains about 75% of our daily requirement of long chain n-3PUFA, but still needs to be consumed at a dose of over 1.5 L to meet a dietary recommendation of 1000 mg/d of long chain n-3PUFA for people at high risk of CVD.
  • • 
    Coles (High Top) bread provides only 37 mg of 20:5n-3 and 22:6n-3 per serve (2 slices). Buttercup (Wonder White) DHA bread contains only 34 mg of 20:5n-3 and 22:6n-3 in 2 slices. Both breads contain per serve less than 15% of what is needed for good heart health and less than 3% of the recommended dose for people at high risk of CVD.
  • • 
    AP Foods (Seachange) omega-3 spread contains 600 mg of long chain n-3PUFA per 100 g. Approximately 35 g/d of this spread must be consumed for a healthy heart and 175 g/d would need to be consumed to obtain sufficient long chain n-3PUFA to benefit those at high risk of CVD.
  • • 
    Biomedical Laboratories (IQ3 Brainstorm) cereal bars in the United Kingdom are made using Nu-Mega's Driphorm powdered fish oils. The fruit-flavored bars, containing 150 mg of 20:5n-3/22:6n-3, are marketed as a way to improve children's performance at school. This appears to be a good way of supplying long chain n-3PUFA in the diets of children.

Conclusions

  1. Top of page
  2. Abstract
  3. Introduction
  4. Dietary Intakes and Recommendations for Long Chain n-3PUFA
  5. Health Benefits and Mechanisms of Action of n-3PUFA
  6. Food Sources of n-3PUFA
  7. Facts about Foods Fortified with Long Chain n-3PUFA
  8. Conclusions
  9. Research Needs
  10. References

Clearly, there is a need to develop foods that can deliver the recommended level of long chain n-3PUFA in convenience foods consumed on a regular basis. n-3PUFA, particularly of marine origin, will continue to be a minority of all the fatty acid classes present in the human diet, even after making a recommendation of 2 to 3 servings of fish and seafood per week. It is not likely that we will start eating fish on a daily basis just because the n-3PUFA are beneficial to health. If everyone in the world starts consuming even 2 to 3 servings of fish per week, the supply of fish will run out very quickly. Innovative methods of providing required amounts of long chain n-3PUFA are needed. Species of algae and fungi have been isolated and cultured for mass production of long chain n-3PUFA free of the toxins that are typically found in some fish. Efforts are being made to insert genes in plants and animals to enable endogenous synthesis of long chain n-3PUFA. Until such gene manipulations are successfully implemented and their safety established, it is imperative that the delivery and the bioavailability of n-3PUFA are optimized. There is some evidence to suggest that the bioavailability of long chain n-3PUFA can be improved by providing n-3PUFA in a food matrix that accelerates their entry into the mucosal cells. Some important points to optimizing the benefits from n-3PUFA supplements, such as fish oil capsules, include the following:

  • 1
    Keep n-6PUFA in the diet as low as possible.
  • 2
    Consume n-3PUFA supplements with a background diet rich in MUFA.
  • 3
    Consume supplements with the meal.
  • 4
    Ensure that sufficient preformed long chain n-3PUFA foods are consumed, rather than relying on foods containing the parent 18:3n-3.
  • 5
    Prefer microencapsulated fish oil capsules over normal capsules.

Research Needs

  1. Top of page
  2. Abstract
  3. Introduction
  4. Dietary Intakes and Recommendations for Long Chain n-3PUFA
  5. Health Benefits and Mechanisms of Action of n-3PUFA
  6. Food Sources of n-3PUFA
  7. Facts about Foods Fortified with Long Chain n-3PUFA
  8. Conclusions
  9. Research Needs
  10. References

It is evident from the information presented in this article that there is a need to develop functional foods that can provide the recommended levels of long chain n-3PUFA, including for those who have already had a cardiovascular event and those at a high risk of developing CHD. It is noteworthy that although foods fortified with higher levels of long chain n-3PUFA need to be developed, the total fat content, particularly the level of SFA, must not exceed the dietary guidelines. The fortified food must be convenient, palatable, with no fishy odor/flavor and no fishy eructation following consumption. The food matrix should provide minimum or no resistance for release of long chain n-3PUFA in the gastrointestinal tract to ensure maximum bioavailability. Particular attention needs to be paid to the material used for microemulsification, as this may be an important criterion for the bioavailability of long chain n-3PUFA. Quantitative data on bioavailability of long chain n-3PUFA from the n-3PUFA enriched foods is lacking in the literature, although acute and chronic effects of consuming these foods on n-3PUFA incorporation have been extensively reported. Other factors, dietary or physiological, which might affect the bioavailability of long chain n-3PUFA also merit further investigation. Perhaps, long chain n-3PUFA can be combined with other nutrients in a single food to optimize their health benefits. One such ideal combination may be the synergistic effects of long chain n-3PUFA and plant sterols on plasma lipids. Plant sterols are known to reduce plasma and LDL cholesterol, while the triglyceride lowering properties of long chain n-3PUFA are well established. The combination of the two may be ideal to achieve overall lipid-lowering effects from a single food. Similarly, long chain n-3PUFA can be combined with other dietary ingredients, such as carotenoids, in order to maximize the anti-inflammatory effects for the prevention of rheumatoid arthritis, asthma, and inflammatory bowel disease. The development of functional foods enriched with larger amounts of long chain n-3PUFA and testing for bioavailability, biological and clinical effects require a concerted team effort, including food scientists/technologists, human/clinical nutritionists, and food producers. Some of these aspects of long chain n-3PUFA are under active investigation in our research laboratories.

References

  1. Top of page
  2. Abstract
  3. Introduction
  4. Dietary Intakes and Recommendations for Long Chain n-3PUFA
  5. Health Benefits and Mechanisms of Action of n-3PUFA
  6. Food Sources of n-3PUFA
  7. Facts about Foods Fortified with Long Chain n-3PUFA
  8. Conclusions
  9. Research Needs
  10. References
  • Appel LJ, Miller ER III, Seidler AJ, Whelton PK. 1993. Does supplementation of diet with ‘fish oil’ reduce blood pressure? A meta-analysis of controlled clinical trials. Arch Intern Med 153:142938.
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