Rigid timetables, pressure to meet deadlines, and hectic daily work can often be an obstacle to a healthy and balanced diet. Instead of preparing light meals from fresh ingredients in a way that will preserve the vitamins they contain people often end up having to still their hunger with a ready meal. And if on account of this they afterwards suffer from a bad conscience many of them will try to ease it by swallowing food supplements in the hope of doing their bodies some good and making up for the presumed nutritional deficiencies. Wouldn’t it be more comfortable and more effective, clever product developers might have thought, to include these helpful food additives right from the outset and in so doing deliver an "added value"? And with that, the idea of "functional foods" was born… foods that are not only filling but at the same time follow a preventive approach and compensate for nutritional deficiencies and counteract diet-related diseases.
Although the term "functional food" is relatively new there have been foods that meet this requirement for quite a long time. The idea of "fortified" products originally came from Japan, where the functional food idea has in the meantime matured to a veritable food concept which today encompasses an almost inconceivable number of products. Almost a fifth of these are officially recognized as real functional food products in Japan and they are traded under the abbreviation FOSHU which stands for "Food for Specified Health Use". Alongside these products there is a much greater fraction which also lays claim to, and advertises, functional added value on the packaging, but are not officially approved as FOSHU. That functional food would be successful in Asia, was actually not surprising, given the fact that a specific health value is traditionally associated with many foods there: some are good for the intestines and liver, while others help with an upset stomach or potency disorders.
In the EU, the term functional food is not legally defined. This allows food manufacturers to advertise any products from fruit juice to margarine and yogurt as "functional" if they are enriched with detectable or presumed health-promoting additives. And in Europe, too, foods that are considered in the literal sense to be functional food were available on the market long before the term itself became established. For example, salt enriched with iodine, fruit juice with an extra portion of calcium, sweets and margarine with added vitamins, or products with added fibre to reduce intestinal transit or have a positive influence on lipid and cholesterol metabolism. Among the particularly popular additives are probiotics (mostly lactic acid bacteria), prebiotics (which include fibres), and synbiotics (which are said to combine the advantages of pro- and prebiotics). There are also vitamins and antioxidants, minerals, trace elements, plant supplements and unsaturated fatty acids, especially the omega 3 type. The "added value" of functional foods is rarely visible because the products mostly continue to enter the market in the usual format. By enriching them with additional substances they only acquire an additional function that goes beyond the nutritional and sensory properties of food. The prime objective is often one of the following:
• to compensate for nutritional deficiencies by enrichment with fibres, amino acids, calcium, selenium, iodine, etc.,
• to correct the typical consequences of particular lifestyles, for example with the help of antioxidants or bioactive substances,
• to provide consumers who suffer from reduced food tolerance, as in the case of allergies, with food products
• to support dietary therapy, for example among people with lipid metabolism disorders.
Functional foods are divided into two different groups. Firstly, foods that in their natural state are already rich in the desired health-promoting ingredients. They are often referred to as intrinsic functional foods. And secondly, foods that gain their positive effect only through controlled supply, enrichment or mixture with health-promoting ingredients (nutraceuticals), also called extrinsic functional foods.
High nutritional value makes seafood a functional food
Fish and seafood have per se numerous components that are good for human health. Because of this inherent functionality it is good and, indeed, recommendable to eat seafood regularly. The production of many species in aquaculture also opens up the possibility of providing the fishes with additional functional properties by giving them specially enriched feed. Seafood can thus be both an intrinsic and an extrinsic functional food. In addition, some of the valuable health-promoting nutraceuticals and bioactive substances that are contained in fish can also be extracted and isolated. Not only the fillets, but also the waste from slaughtering and processing, i.e. the skin, head, bones and intestines, often contain many of these ingredients. Such isolates can then in turn be used to enrich other products (e.g. bread, eggs, dairy products) in order to give them additional functional properties, too.
Many experts believe that natural seafood products offer greater health benefits than extrinsic functional foods. This is because natural products do not only possess the aforementioned inherent functionality, i.e. numerous valuable ingredients, but also contain these substances in their "natural complexity." By this is meant that nature offers all the different components and ingredients in an optimal, if not to say perfect, blend. All substances and nutrients are in balance with each other, they are embedded in a "tissue matrix" and therefore protected. This ensures, among other things, that they maintain their effectiveness over a long period of time, are not present in excess quantities, and are digested more slowly, and thus exert their beneficial effect in the body of the consumer only gradually.
It has long been undisputed that fish is one of the healthiest foods. Recent studies have increasingly revealed more and more valuable ingredients and their health-promoting effects. The integrated European research project SEAFOODplus and the network for marine functional food (MARIFUNC) in which research institutes from five Nordic countries were involved provided important insights into the health value of fish. The results of these projects demonstrate not only the important contribution that fish makes to seafood consumers’ health but also point to the substances that are responsible for these effects.
The best-known ingredients in fish that have a functional effect are probably the long-chain polyunsaturated fatty acids ("PUFAs") of the omega 3 type, especially EPA and DHA. In the 1970s it was first presumed that the low rate of heart attacks and coronary artery disease of the Inuit in Greenland was due to their EPA and DHA-rich diet. Since then, not only has this effect been proved beyond reasonable doubt, but other positive effects of the omega 3 fatty acids have been observed. Among other things they reduce the risk of some cancers, promote brain development and cognitive abilities in infancy, and help prevent Alzheimer's disease. The main sources of EPA and DHA are fatty fish such as salmon, mackerel and herring. While nuts and some vegetable oils also contain omega 3 fatty acids these are mostly alpha-linolenic acid (ALA), which is also one of the essential fatty acids, but one of which the human body can only convert just under 5% to the far more important EPA and DHA. Consumption of fatty fish is thus the easiest and most reliable way to guarantee an adequate supply of valuable fatty acids. Already an average portion of salmon or mackerel already covers our daily requirement of EPA and DHA. And since the two fatty acids are relatively heat stable, they remain biologically effective in canned and hot smoked products.
Less well known but equally valuable are bioactive proteins and peptides in fish. These substances inhibit the angiotensin I-enzyme (ACE for Angiotensin I-Converting Enzyme) and thus promote the dilation of the blood vessels, resulting in a hypotensive effect. Japanese researchers have identified in mussels and sardines alone more than a dozen such ACE inhibitory peptides. A specific protein of the blue whiting is said to stimulate the formation of an intestinal hormone that curbs appetite and could be helpful in combating obesity. And highly specific substances that block the enzyme PEP (prolyl endopeptidase) not only exist in red wine, green tea or some herbal extracts but also in the flesh of cod, salmon and trout. This enzyme is directly connected with neuro-degenerative disorders such as memory disorders and possibly Alzheimer's disease (Alzheimer's disease patients have very high PEP activity). And the PEP enzyme appears to play a role in depression, schizophrenia and autism, too. Regular consumption of fish helps prevent such diseases.
The importance of taurine in fish was long underestimated. Since the human body can produce taurine itself it was assumed that additional supply via the diet was unnecessary… Or perhaps only necessary in the case of vegetarians, because taurine is only present in animal protein, but not in plants. A few years ago the importance of the amino acid taurine for the human organism was re-evaluated. Taurine is important for the development of the brain, the retina of the eye, and the liver in newborns. It facilitates the passage of important substances into the bloodstream, promotes fat burning and the absorption of fat-soluble vitamins, guards against cardiovascular disorders, oedema and high blood pressure. Another argument in favour of fish consumption is the high content of antioxidants it contains. Antioxidants prevent premature cell aging and can at least in test tube experiments even check the spreading of cancer cells within the tissue. One of the many important trace elements which are found in fish is selenium. Because selenium reduces the risk of colon, prostate and lung cancer the EC Directive 90/496/EC recommends a daily intake (RDI) of 55 µg which is easily to be covered with a lot of seafood products.
A more certain and more elegant way would obviously be to enrich the fish fillet additionally with selenium, thereby making the fish into an extrinsic functional food. This is exactly what researchers succeeded in doing in the context of SEAFOODplus: they mixed some garlic, which has strong selenium-absorbing properties, into the feed of African catfish. It was also possible to increase the taurine content in fish in the same way. Because the enrichment of live fish with health-promoting substances is relatively complicated and the outcome difficult to predict, it is in practice easier to mix the functional substances into the products during processing. This mostly works without any major problems with dietary fibres such as apple pomace, a waste product during juice production. 50 per cent of apple pomace consists of fibres, and the pomace contains pectin and gallic acid which have a cholesterol reducing effect and bind free radicals. In products with minced mackerel (such as burgers or lasagna) no taste impairment was perceptible with a "fruit share" of up to about 2 to 3%.
Seafood components as nutraceuticals in other foods
Enrichment of other kinds of foods with bioactive substances derived from fish and seafood is extremely popular. The omega-3 fatty acids are well to the fore in terms of popularity. They are to be found in eggs, bread, sausage and dairy products and various spreads for example, and are particularly well-liked in North America because they meet the American Heart Association’s dietary recommendations for increased intake of DHA and EPA, promising health benefits without consumers having to make drastic changes to their eating habits. But the list of marine nutraceuticals and bioactive substances that can be considered as health promoting additives for functional food is much longer. In addition to omega 3 fatty acids there are now several fish hydrolysates and antioxidant peptides derived in part from the skin of pollock, acid-soluble collagen from the bones and scales of individual species and chitosan, various chitosan oligomers and glucosamine from crustacean shells, which serve as a source of calcium (whose health value in functional foods, however, is highly controversial).
More and more consumers are wondering anyway which physiological and biochemical effects of functional food have actually been tested and scientifically proven and whether the promises made by food manufacturers are really correct or whether an excessive intake might not even be harmful. Even some vitamins that are useful and essential in normal doses can decalcify bone and thus have negative effects in larger quantities. From a nutritional perspective, the benefits of functional foods are usually only achieved when consumed as part of a varied mixed diet. And there is growing distrust because many people no longer understand how everything fits together, and deep down they have the feeling that producers are unnecessarily “messing about” with food on which humanity has fed for thousands of years without any problems. More important than the food industry’s advertising claims would therefore probably be campaigns to improve awareness and the level of knowledge and acceptance of functional foods.
In spite of numerous directives and legal regulations concerning food the EU still has no explicit rules governing functional food. At the moment there is not even a clear definition of what functional food actually is and whether it should be categorized as food, as something therapeutic, or even as medication. Each EU member state handles the problem differently. In Germany, for example, there are special regulations for dietary supplements (NemV), dietary foods (DiätV) and Novel Food (NFV), which also in part relate to functional food. In essence, however, functional food products are covered under the general food law. This at least ensures that the products comply with the applicable regulations for health and fraud protection of consumers. The Health Claims Regulation (EC no. 1924/2006) of the European Parliament on nutrition and health claims made on foods has also been in force since July 2007. It obliges manufacturers to provide truthful information on the health value of their products. Some advertising claims are only permitted if scientific evidence is available. This applies, for example, to general statements which are clearly associated with health such as "beneficial to blood circulation", "reduces cholesterol" or "strengthens the immune system". Such “claims” are only allowed if they are listed as such in the Community Register. Even indisputably correct statements such as "calcium is good for your bones" may only be used for promotional purposes if they are included in the positive list of generic health claims.
Although a varied and balanced diet is still the best and easiest method to avoid nutritional deficiencies or even compensate for unhealthy splurges the range of, and the market for, functional foods will continue to grow in the coming years. For the manufacturers of such products the temptation to enter into previously untapped market gaps and to develop new sales opportunities is simply too great to pass up on a voluntary basis. We can probably be sure that in future fish and seafood will play a greater and more important role in this development than in the past.