Nutrients and Chemical Pollutants in Fish and Shellfish. Balancing Health Benefits and Risks of Regular Fish Consumption

Dietary patterns and lifestyle factors are clearly associated with at least five of the ten leading causes of death, including coronary heart disease, certain types of cancer, stroke, non-insulin insulin-dependent diabetes mellitus, and atherosclerosis. Concerning specifically fish and seafood consumption, its beneficial health effects in humans are clearly supported by an important number of studies performed in the last 30 years. These studies have repeatedly linked fish consumption, especially those species whose contents in omega-3 fatty acids are high, with healthier hearts in the aging population. The nutritional benefits of fish and seafood are also due to the content of high-quality protein, vitamins, as well as other essential nutrients. However, a number of studies, particularly investigations performed in recent years, have shown that the unavoidable presence of environmental contaminants in fish and shellfish can also mean a certain risk for the health of some consumers. While prestigious international associations as the American Heart Association have recommended eating fish at least two times (two servings a week), based on our own experimental results, as well as in results from other laboratories, we cannot be in total agreement with that recommendation. Although a regular consumption of most fish and shellfish species should not mean adverse health effects for the consumers, the specific fish and shellfish species consumed, the frequency of consumption, as well as the meal size, are essential issues for adequately balancing the health benefits and risks of regular fish consumption.     

Nutritional composition of fats in seafoods

Public interest in the health benefits of seafood lipids, or of fish oils, is a most unusual phenomenon because for once the recommendations of health authorities to "eat more fish" are in accord with newer and popular attitudes. Media exploitation of the more sensational health aspects is also generally in favor of more consumption of seafood. The public is however still confused by the multitude of species of fish and shellfish available, and in a quandary over whether fatty fish are risky in terms of calories or cholesterol, or of more benefit than lean fish in terms of omega-3 fatty acids. Most direct questions on how much omega-3 fatty acids are useful in the diet of an average individual may never be answerable until long term studies with humans are carried out. It does appear that marine fish can be broken down into four convenient categories: lean (including shellfish), low fat, medium fat and high fat; and in this review it is suggested that these could contribute, per 100 grams, respectively about 250, 750, 1000 and 2000 mg of total C20 + C22 omega-3 fatty acids. This intake can compare favorably with the alternative of commonly available fish oil capsules. Moreover this survey shows that at present the composite of total omega-3 fatty acids in fish and shellfish may contain roughly equal proportions of the functionally effective eicosapentaenoic acid, and of docosahexaenoic acid with its as yet unknown long-term biochemical effects, or be biased in favor of more of the latter. To assist the public, nutritionists, dietitians, and researchers this review discusses the distribution of fat in edible fish muscle, the classes of lipids encountered, and the major fatty acids of health interest. Included are limited numbers of analyses from parts of the world other than North America.     

Science opens new horizons for marine lipids in human nutrition

Abstract

Until the past few decades, lipids contained in plants and animals from the marine and freshwater bodies of the world have not been considered important to human nutrition. Today, with the findings that highly unsaturated omega‐3 (n‐3) fatty acids in marine lipids can be important in preventing or reducing certain premature heart diseases, inflammatory disorders, and many other health problems, there is an increasingly active interest in seafood and its component oils. A review of the role of lipids in human nutrition must also include consideration of the source of marine lipids and how the fishing industry can, and does, get high‐quality oils to the consumer. There are many practical considerations involved in the harvesting or growing of seafood, processing the products, and handling and distributing to market that must be considered in the overall program of getting prople to consume more n‐3 fatty acids. Except in regard to those persons requiring medical attention and needing large doses of n‐3s, marine lipids should only be considered in the highly nutritious food category. This includes, high‐quality seafood, food supplement oil and capsules, and prepared foods contining component fish oil.     

Quantitative risk–benefit analysis of fish consumption for women of child-bearing age in Hong Kong

Maternal fish consumption is associated with both risks from methylmercury (MeHg) and beneficial effects from omega-3 fatty acids to the developing foetal brain. This paper assessed the dietary exposure to MeHg of women of child-bearing age (20–49 years) in Hong Kong, and conducted risk–benefit analysis in terms of the effects in children’s intelligent quotient (IQ) based on local data and the quantitative method derived by the expert consultation of FAO/WHO. Results showed that average and high consumers consume 450 and 1500 g of fish (including seafood) per week, respectively. About 11% of women of child-bearing age had a dietary exposure to MeHg exceeding the PTWI of 1.6 µg kg^–1 bw. In pregnant women MeHg intake may pose health risks to the developing foetuses. For average consumers, eating any of the 19 types of the most commonly consumed fish and seafood during pregnancy would result in 0.79–5.7 IQ points gain by their children. For high consumers, if they only ate tuna during pregnancy, it would cause 2.3 IQ points reduction in their children. The results indicated that for pregnant women the benefit outweighed the risk associated with eating fish if they consume different varieties of fish in moderation.     

Metal(loid) contamination in seafood products

Seafood products are important sources of proteins, polyunsaturated lipids and phospholipids, and also of numerous micronutrients (vitamins and minerals). However, they may also present chemical contaminants that can constitute a health risk and that must be considered when evaluating the risk/benefit associated with consumption of this group of foods. Toxic metals and metalloids in seafood, such as mercury (Hg), cadmium (Cd), arsenic (As), and lead (Pb), are subjected to legislative control in order to provide the consumer with safe seafood. This review provides an exhaustive survey of the occurrence of these toxic metal(loid)s in seafood products, and of the risk resulting from their consumption. Consideration is given to aspects related to speciation, food processing, and bioavailability, which are key factors in evaluating the risk associated with the presence of these toxic trace elements in seafood products.     

Importance of instrumental and sensory analysis in the assessment of oxidative deterioration of omega‐3 long‐chain polyunsaturated fatty acid‐rich foods

Omega‐3 long‐chain polyunsaturated fatty acids (LC PUFA) positively influence human health. Their main dietary source is fish, especially fish oil. Owing to low fish consumption in many Western countries the average intake of omega‐3 LC PUFA is below the recommended level. This raises interest in diet supplementation and food enrichment with fish oil. However, due to a high degree of unsaturation fish oil is extremely susceptible to oxidation. Oxidation of fish oil increases when added to food products, which may be enhanced by some antioxidants, under certain conditions. For quality control of omega‐3 LC PUFA‐containing foods adequate and combined methods of oxidation assessment should be used, beginning from the raw material and continuing during processing, storage and distribution. To achieve this goal correlation of instrumental and sensory methods with multivariate data analysis may give the best results. In this paper problems of oxidation of fish oil and fish oil‐containing foods, as well as methods for its assessment, are reviewed. Copyright © 2006 Society of Chemical Industry     

A Comprehensive Overview of the Risks and Benefits of Coffee Consumption

Findings on both the health benefits and the potentially harmful effects of coffee consumption have been contradictory. However, the general scientific consensus is that moderate, regular coffee drinking by healthy individuals is either essentially benign or mildly beneficial.  Results and generalizations are complicated by a number of factors, including differences in age, gender, health status, type of coffee preparation, serving size, and source of coffee. Coffee may have potential health benefits and risks, but causality cannot be established for either with the research currently available as these are largely based on observational data.  This review aimed to provide a comprehensive overview of the risks and benefits of coffee consumption on health outcomes.  A systematic search (search terms: “coffee” OR “coffee adj3” [consum* or intake* or drink*]) of the literature (from 1970; humans; in English) using the electronic databases “OVID,” “CINAHL,” and “Web of Knowledge” returned 12405 results. Duplicates were removed, studies were screened (based on inclusion/exclusion criteria), and the remaining eligible studies (n = 1277) were used to collate an exhaustive list of the potential health benefits and risks of coffee consumption, which were grouped and are discussed with regard to major diseases/conditions (mortality, cardiovascular disease, cancer, and metabolic/liver/neurological disorders), at‐risk/vulnerable groups, and specific coffee constituents. This qualitative assessment has shown that the health benefits (or null effects) clearly outweigh the risks of moderate coffee consumption in adult consumers for the majority of health outcomes considered. Results from this research may aid further qualitative and quantitative deterministic risk–benefit assessments of coffee consumption.     

Mercury,selenium, PCBs and fatty acids in fresh and canned fish available on the Slovenian market

In order to contribute to the general understanding of the risks and benefits of consuming fish and fish products, total mercury (THg), monomethylmercury (MeHg), polychlorinated biphenyls (PCBs), selenium (Se), n-3 and n-6 fatty acids were determined in fresh and canned fish on the Slovenian market. Furthermore, the mercury exposure of pregnant women in Slovenia was assessed by determining total mercury (THg) in hair, and through fresh and canned fish consumption obtained by a food frequency questionnaire. Based on the frequency of fish consumption and levels of MeHg, THg and PCBs determined in the present study, it can be concluded that fish available on the Slovenian market do not represent a health risk. It was also confirmed that fish are important sources of selenium and n-3 fatty acids.     

Food of marine origin: Between benefits and potential risks. Part I. Canned fish on the Polish market

Chemical analyses were performed on 12 of the most popular varieties of canned fish on the Polish market. The contents of the nutritive substances of canned fish (protein, micro and macroelements, vitamins A₁, D₃, E, and fatty acids) and certain contaminants were determined. It was confirmed that canned fish is a good source of digestible proteins, fluoride, iodine, selenium, and vitamin D₃. The fundamental nutritive benefit of processed fish is the highly advantageous fatty acid composition, which imparts healthful effects. The high content of long-chained polyunsaturated fatty acids, which is not noted in other food products, is especially important.     

Biogenic amines in fish, fish products and shellfish: a review

Fish, cephalopods and shellfish provide a healthy source of high-quality proteins, essential vitamins, minerals and polyunsaturated fatty acids. The beneficial effects of fish consumption on human health such as protection against coronary heart disease and certain cancer may be offset by fish decomposition and the formation of chemical contaminants such as biogenic amines. There are several toxicological effects of biogenic amines on humans, especially histamine. It is the causative agent of histamine or scombroid fish poisoning which is a significant public health problem. In individuals with diminished histamine detoxification, ingestion of even a low or moderate histamine- or tyramine-containing fish may lead to food intolerance. Biogenic amines such as putrescine, tyramine and cadaverine can potentiate histamine toxicity. Furthermore, dietary polyamine intake should be minimised in some cancer patients. Besides their potential toxicity, biogenic amines are used for the evaluation of hygienic quality of different marine and freshwater species. Spoilage pattern and biogenic amine formation are species specific. Histamine has been traditionally used as an indicator of the quality of histidine-rich fish (dark-muscle fish). On the other hand, putrescine and cadaverine are the most objective indicators of quality of histidine-poor fish (white-muscle fish), shellfish and fermented seafood products.     

Biogenic amines in fish,fish products and shellfish: a review

Fish, cephalopods and shellfish provide a healthy source of high-quality proteins, essential vitamins, minerals and polyunsaturated fatty acids. The beneficial effects of fish consumption on human health such as protection against coronary heart disease and certain cancer may be offset by fish decomposition and the formation of chemical contaminants such as biogenic amines. There are several toxicological effects of biogenic amines on humans, especially histamine. It is the causative agent of histamine or scombroid fish poisoning which is a significant public health problem. In individuals with diminished histamine detoxification, ingestion of even a low or moderate histamine- or tyramine-containing fish may lead to food intolerance. Biogenic amines such as putrescine, tyramine and cadaverine can potentiate histamine toxicity. Furthermore, dietary polyamine intake should be minimised in some cancer patients. Besides their potential toxicity, biogenic amines are used for the evaluation of hygienic quality of different marine and freshwater species. Spoilage pattern and biogenic amine formation are species specific. Histamine has been traditionally used as an indicator of the quality of histidine-rich fish (dark-muscle fish). On the other hand, putrescine and cadaverine are the most objective indicators of quality of histidine-poor fish (white-muscle fish), shellfish and fermented seafood products.     

Shellfish: Nutritive Value,Health Benefits,and Consumer Safety

Shellfish is a major component of global seafood production. Specific items include shrimp, lobsters, oysters, mussels, scallops, clams, crabs, krill, crayfish, squid, cuttlefish, snails, abalone, and others. Shellfish, in general, contain appreciable quantities of digestible proteins, essential amino acids, bioactive peptides, long‐chain polyunsaturated fatty acids, astaxanthin and other carotenoids, vitamin B₁₂ and other vitamins, minerals, including copper, zinc, inorganic phosphate, sodium, potassium, selenium, iodine, and also other nutrients, which offer a variety of health benefits to the consumer. Although shellfish are generally safe for consumption, their exposure to diverse habitats, the filter feeding nature of shellfish such as oysters, clams, and mussels, and unhealthy farming and handling practices may occasionally entail health risks because of possible presence of various hazards. These hazards include pathogenic organisms, parasites, biotoxins, industrial and environmental pollutants, heavy metals, process‐related additives such as antibiotics and bisulfite, and also presence of allergy‐causing compounds in their bodies. Most of the hazards can be addressed by appropriate preventive measures at various stages of harvesting, farming, processing, storage, distribution, and consumption. Furthermore, consumer safety of shellfish and other seafood items is strictly monitored by international, governmental, and local public health organizations. This article highlights the nutritional value and health benefits of shellfish items and points out the various control measures to safeguard consumer safety with respect to the products.     

Manipulation of Omega‐3 PUFAs in Lamb: Phenotypic and Genotypic Views

A number of studies have shown that dietary omega‐6 and omega‐3 long‐chain fatty acids can be incorporated into muscle tissue of ruminants despite the biohydrogenation of dietary fatty acids in the rumen. The main focus of this review is on eicosapentaenoic (20:5n‐3) and docosahexaenoic (22:6n‐3) fatty acids because health authorities around the world consider the sum of these fatty acids as the basis of classifying a food as a source or good source of omega‐3 polyunsaturated fatty acids (PUFAs). A high proportion of polyunsaturated fatty acids are hydrogenated in the rumen, leading to a higher concentration of 18:0, but some escapes the rumen to be absorbed intact by the small intestine. Feeding strategies for ruminants have been successfully applied to increase the absorption of PUFAs in the small intestine and therefore to increase the levels of PUFAs in muscle tissue. Protected fats and algae are strong candidates to improve the nutritional value of red meat in ruminants in terms of health‐claimable omega‐3 fatty acids. Efforts to understand the genetic basis of fatty acid metabolism have been underway. The knowledge of the main genes which control the output of omega‐3 fatty acids is still lacking, but gene expression studies have helped to explain the deposition of these acids in muscle, liver, and subcutaneous fat.     

Evaluating daily exposure to polychlorinated biphenyls and polybrominated diphenyl ethers in fish oil supplements

Fish oil supplements have become a popular means of increasing one's dietary intake of essential polyunsaturated fatty acids. However, there is growing concern that the levels and potential health effects of lipophilic organic contaminants such as polychlorinated biphenyls (PCBs) and polybrominated diphenyl ethers (PBDEs) may diminish some of the health benefits associated with the daily consumption of fish oil supplements. In this study, ten over-the-counter fish oil supplements available in the United States were analysed for PCBs and PBDEs and daily exposures calculated. Based on manufacturers’ recommended dosages, daily intakes of PCBs and PBDEs ranged from 5 to 686 ng day^?1 and from 1 to 13 ng day^?1, respectively. Daily consumption of fish oil supplements expose consumers to PCBs and PBDEs. However, in comparison with fish ingestion, fish supplements may decrease daily PCB exposure and provide a safer pathway for individuals seeking to maintain daily recommended levels of polyunsaturated fatty acids.     

Chia Seed (Salvia hispanica L.) as a Source of Proteins and Bioactive Peptides with Health Benefits: A Review

The consumption of chia seed (Salvia hispanica L.) has increased in recent years due its high content of omega‐3 fatty acids and dietary fiber. This seed also has a high concentration of proteins and essential amino acids, becoming a promising source of bioactive peptides. The objective of this review was to identify the composition and the beneficial effects of chia seeds (S. hispanica L.), their proteins, peptides, and their potential impact on human health. The UniProt database was used to identify the chia proteins and their amino acid sequences. The BIOPEP database was used to analyze the peptides's bioactive potential. A total of 20 proteins were cataloged in chia seed, 12 of those were involved in the regular metabolic processes of the plant cells. However, eight proteins were specifically related to production and storage of plant lipids, thus explaining the high concentration of lipids in chia seeds (around 30%), especially omega‐3 fatty acids (around 20%). The analyses of amino acid sequences showed peptides with bioactive potential, including dipeptidyl peptidase‐IV inhibitors, angiotensin‐converting enzyme inhibitors, and antioxidant capacity. These results correlated with the main health benefits of whole chia seed in humans such as antioxidant capacity, and hypotensive, hypoglycemic, and anticholesterolemic effects. Such relation can be associated with chia protein and peptide compositions and therefore needs further investigation in vitro and in vivo.     

Dietary intake of isoflavones and polyunsaturated fatty acids associated with lung function,breathlessness and the prevalence of chronic obstructive pulmonary disease: Possible protective effect of traditional Japanese diet

The Japanese diet is high in soy products and fish. A case–control study was conducted in Japan to investigate the relationship between dietary intake of isoflavones and fatty acids and lung function, breathlessness and chronic obstructive pulmonary disease (COPD). A total of 278 referred patients aged 50–75 years with COPD diagnosed within the past 4 years, and 340 community‐based controls were assessed for respiratory symptoms and undertook spirometric measurements of lung function. A validated food frequency questionnaire was administered face‐to‐face to obtain information on habitual food consumption. Dietary intakes of isoflavones and fatty acids were derived from the Japanese food composition tables. The COPD patients had significantly lower habitual intakes of isoflavones (genistein and daidzein) and polyunsaturated fatty acids (PUFA; both omega‐3 and omega‐6) than control subjects. Lung function measures were found to be positively associated with isoflavones and PUFA intake. Substantial reductions in prevalence of COPD and breathlessness were observed for isoflavones, the respective adjusted odds ratio being 0.36 (95% confidence interval 0.19–0.68) and 0.60 (95% confidence interval 0.33–1.10) for the highest versus lowest levels of total isoflavone intake. The corresponding tests for linear trend were significant. High intakes of PUFA and omega‐6 fatty acids (derived from foods excluding oils and fats as seasonings) also appeared to reduce the risks of COPD and breathlessness symptom, but no evidence of association was found for other types of fatty acids. The study provided evidence of possible protective effect of traditional Japanese diet against tobacco carcinogens.     

SEAFOODplus – how to provide health promoting, safe seafood of high eating quality to consumers

The strategic objective of the SEAFOODplus Integrated Project is to reduce health problems and to increase well-being among European consumers by applying the benefits obtained through consumption of health promoting and safe seafood products of high eating quality. The relevance of seafood in the diet to diminish the increased incidences of e.g. cardiovascular, cancer and inflammatory diseases is being assessed by performing dietary intervention and epidemiological studies. Other focus areas are health of young populations, to treat overweight, to prevent osteoporosis and postpartum depression observed for women giving birth. Seafood’s importance for consumer behaviour and well-being is assessed to understand determinants of consumers’ seafood consumption and to adapt seafood products to consumer demands. The objectives of the seafood safety component are to make seafood safe for the consumer, by identifying risk factors and avoiding risks caused by viral and bacterial contamination and biogenic amines in seafood. The total value chain is addressed by developing consumer driven tailor-made, functional seafood products to improve health and to ensure nutritional quality and safety by full utilisation of raw materials from aquaculture and from traditional fisheries. The aquaculture component will study the effects of dietary modulation, husbandry, fish physiology, genetics and pre-slaughter conditions. Validated traceability systems are assessed to make it possible to apply a total chain approach from the live fish to the consumer product, and to trace back any feature from fork to farm. Received: January 7, 2008; accepted January 8, 2008     

Fatty Acid Composition of 12 Fish Species from the Black Sea

Abstract: The long‐chain polyunsaturated fatty acids docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) are healthful to humans, particularly in promoting growth and cognitive development in infants and young children, and in reducing the risk of cardiovascular disease. Though the populations who inhabit the Trabzon province of Turkey include seafood from the Black Sea in their diet, knowledge of the fatty acid composition and content of these fish is scant. Fatty acid analysis was performed on freeze‐dried muscle tissue of 12 species of fish purchased in markets in Trabzon. The fat content varied from 0.2% (garfish) to 12% (shad) of dry weight. The highest DHA and DHA plus EPA contents were found in horse mackerel 16.1 and 20.6 mg/g dry weight, respectively. Only in sea bass and sea bream did the essential fatty acid linoleic acid account for more than 10% of the fatty acid total. For all 12 species, arachidonic acid accounted for 0.09% to 7.64% of the fatty acid total. Oleic acid varied greatly from 0.14% (garfish) to 32.7% (shad). The omega‐3/omega‐6 fatty acid ratio ranged from 0.8 to 25. A 100 g serving of fresh horse mackerel would contribute 586 mg of DHA to the diet, which exceeds the recommended daily intake of 200 to 300 mg of DHA for pregnant and lactating women. These data indicate that some, but not all, of the 12 fish species from the Black Sea fish we studied could contribute significantly to satisfy the DHA and EPA needs of the inhabitants of the eastern Black Sea region of Turkey. Practical Application: The information in the present paper will be of practical value from a health perspective for populations who consume these fish and for food producers, as well as scholars interested in fishery and aquaculture and biodiversity and marine ecology when we consider an increasing pollution of our marine ecosystem in our green planet.     

The New Paradigm for Lipid Oxidation and Insights to Microencapsulation of Omega‐3 Fatty Acids

The consumption of omega‐3 fatty acids provides a wide range of health benefits. However, the incorporation of these fatty acids in foods is limited because of their high oxidative instability. A new paradigm has emerged to better explain the oxidation mechanism of polyunsaturated fatty acids, which will be discussed here with reference to bulk lipids considered a special case of water in oil microemulsion. This paradigm suggests that lipid oxidation reactions are initiated by heterogeneous catalysis by metal oxides followed by the formation of micelles containing initial hydroperoxides, water, and other amphiphilic compounds. The induction period comes to the end when the formed micelles reach a critical micelle concentration and start to decompose opening the way to intense free radical reactions. Antioxidants and synergists extend the induction period not only by scavenging free radicals but also by stabilizing the micelles. With better understanding of the lipid oxidation mechanism, a tailored choice of antioxidants and synergistic combinations, and efficient encapsulation methods may be optimized to provide stable encapsulates containing highly n‐3 polyunsaturated fatty acids. Smart processing and encapsulation technologies utilizing properly stabilized oils as well as optimized packaging parameters aiming to enhance n‐3 fatty acid stability by smart selection/design of antioxidants, control of the interfacial physics and chemistry, and elimination of surface oil are needed for this purpose.     

Health benefits of seafood; Is it just the fatty acids?

There is a considerable body of literature suggesting a wide range of health benefits associated with diets high in seafood. However, the demand for seafood across the world now exceeds that available from capture fisheries. This has created a rapidly increasing market for aquaculture products, the nutrient composition of which is dependent on feed composition. The use of fishmeal in this food chain does little to counteract the environmental impact of fisheries and so the on-going development of alternative sources is to be welcomed. Nevertheless, an in-depth understanding as to which nutrients in seafood provide benefit is required to permit the production of foods of maximal health benefit to humans. This paper reviews our current knowledge of the beneficial nutrient composition of seafood, in particular omega-3 fatty acids, selenium, taurine, vitamins D and B12, in the context of the development of environmentally sustainable aquaculture.