Risks and Benefits of Seafood - ACS Publications - American

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R i s k s and B e n e f i t s of S e a f o o d BRENDA C. HIGGINS and ALBERT C. KOLBYE Downloaded via TUFTS UNIV on July 10, 2018 at 00:22:15 (UTC). See https://pubs.acs.org/sharingguidelines for options on how to legitimately share published articles.

The Nutrition Foundation, Inc., Washington, DC 20006 Health Benefits Seafood is a wholesome and healthful food. Today's health conscious consumer would do well to eat more fish for a variety of reasons. First, most fish products are lower in calories than meat and poultry because (1) they usually contain more moisture and less fat. Shellfish, too, are very low in fat, but some may be high in cholesterol. Fish protein differs from that of meat because it has less connective tissue and no elastin (2). It is easily digested and recommended for many therapeutic diets because it lacks elastin and the collagen converts to gelatin during cooking. The fat content of fishery products is lower than that of meats, but the protein content of fish is as high because fish protein is of equivalent biological value (3). Knowing the relative value of fish protein, one can compare a serving of meat with a serving of fish: a three-ounce serving of steak contains 330 calories, 27 grams of fat and 20 grams of protein. A serving of halibut, on the other hand, contains only 155 calories, 7 grams of fat and 23 grams of protein. The halibut, therefore, has half the calories and one-fourth of the fat contained in the steak, but provides just as much protein of equivalent biological value (4). Fish may be divided into two classes: lean fish, such as haddock, whiting and flounder, which contain little fat — less than two and a half percent — and fat fish, such as herring, trout, salmon and bluefish, which usually contain 10 to 25 percent fat (3). Shellfish, too, are low in calories, have good quality protein and are particularly excellent sources of trace elements such as copper, iron, zinc and manganese. Oysters are especially rich in iron, zinc and manganese. Salt water fish 0097-6156/ 84/0262-0059$06.00/0 © 1984 American Chemical Society

Ragelis; Seafood Toxins ACS Symposium Series; American Chemical Society: Washington, DC, 1984.

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are r i c h sources of iodine, but most f i s h are poor sources of the minerals calcium and i r o n (1). F i s h are low i n sodium, even i f they are s a l t water f i s h , and can be used i n low sodium d i e t s . Some s h e l l f i s h , however, do not have t h i s same d i s t i n c t i o n ; but, oysters and soft clams are low i n sodium and are the exception (5). Sixty t o eighty-five percent of the f a t t y acids i n f i s h e r y products are either monounsaturated or polyunsaturated. Polyunsaturated f a t s have been shown to reduce blood cholesterol l e v e l s and the same phenomenon e x i s t s for f i s h o i l s . Epidemiological studies of the Greenland Eskimos show their d i e t to be high i n marine o i l s and the population has correspondingly low serum cholesterol values (6) (7). In addition, the myocardial i n f a r c t incidence among these Eskimos i s low and their blood plasma and p l a t e l e t s contain high l e v e l s of the f a t t y acid, eicosapentaenoic acid, which i s an analog of arachidonic acid (6). The action of t h i s omega-3 f a t t y a c i d may be i t s a b i l i t y to i n h i b i t the formation of thromboxane fy, a blood aggregating agent. Indeed, the Greenland Eskimo data show bleeding time to be longer than among a control group of Danes who had l e s s f i s h i n the d i e t and, consequently, l e s s eicosapentaenoic a c i d (7). The threshold amount of eicosapentaenoic acid needed to p r e c i p i t a t e these changes i n blood c l o t t i n g time and the incidence of myocardial i n f a r c t i s unknown. The mechanism for these observations i s not completely understood. Most tissues of the body incorporate omega-3 f a t t y acids from a d i e t r i c h i n f i s h . I t has been suggested that omega-3 f a t t y acids are e s s e n t i a l for l i f e , but they cannot be synthesized by the human body. Other possible sources of these f a t t y acids, i n addition to f i s h , are not completely d e f i n e d (7). Some f i s h o i l s are used to make margarine and shortening. The end products of the hydrogenation of f i s h o i l s used i n margarines have been examined f o r t h e i r r e l a t i o n to the development of heart disease, a concern which i s i n d i r e c t contrast to f i s h o i l ' s p o t e n t i a l l y p r o t e c t i v e e f f e c t s . Upon hydrogenation, f i s h o i l s , e s p e c i a l l y the longer chain f a t t y acids (C22's), form many new p o s i t i o n a l and geometric isomers. In some cases, p a r t i a l l y hydrogenated f i s h o i l s may contain as many as 50% of the docosenoic acids i n the trans form as opposed to the n a t u r a l l y occurring c i s form. I t i s these trans isomers which may be responsible for the l i p i d o s i s of heart and s k e l e t a l muscle found i n monkeys. Epidemiological studies of populations with high intakes of docosenoic acids,


HIGGINS AND KOLBYE

Risks and Benefits of Seafood

however, do not y i e l d higher rates of myocardial lesions. the excessive s u s c e p t i b i l i t y of laboratory animals i s not confirmed i n populations (6).

'Thus,

Obviously, i n order for f i s h e r y products to be of a health benefit, they must be consumed. The high p e r i s h a b i l i t y of f i s h e r y products creates some d i f f i c u l t y for both the government and industry to provide wholesome and appealing products (8). The consumption pattern of f i s h e r y products i n the United States attests t o the d i f f i c u l t y i n handling marine products. Per capita consumption of f i s h i s not uniform throughout the country; some data indicate that consumption i s much higher i n coastal areas (about twice the average) where f i s h of high q u a l i t y i s r e a d i l y accessible. I t i s much lower i n inland areas where the q u a l i t y of fresh f i s h available t o consumers may be r e l a t i v e l y poor. Unfortunately, when individuals have a bad experience with a f i s h e r y product, they tend t o exclude a l l f i s h e r y products from the d i e t (9). I t seems i r o n i c , but one of the factors which makes f i s h e r y products so a t t r a c t i v e from a health standpoint a l s o makes i t not only undesirable, but a c t u a l l y unpalatable. That factor i s the o i l . F i s h o i l oxidizes r e a d i l y i n a i r , which changes the color to brown or dark red, and has a d i s t i n c t i v e smell. Not only i s the q u a l i t y reduced, but the peroxide i n the l i p i d may be t o x i c o l o g i c a l l y active (8). This phenomenon of rancidity i s a problem, p a r t i c u l a r l y when making salted or d r i e d f i s h products. L i p i d oxidation takes place i n fresh and frozen seafood, too, and can be catalyzed by metal ions. This factor becomes a concern throughout the handling of f i s h e r y products from the time of harvesting a l l the way through processing. Another problem i s that oxidized unsaturated l i p i d s bind t o protein and form insoluble l i p i d - p r o t e i n complexes. These complexes account for some of the toughened texture, poor flavor and unappealing odor of poorly stored, c h i l l e d or frozen seafood (10). Storage temperatures are c r i t i c a l t o the safety and p a l a t a b i l i t y of seafood. Fresh, wet f i s h should be kept as close to 32°F as possible, and frozen f i s h should be kept as cold as possible — not higher than 0°F (9). While cold storage i s an excellent way to preserve f i s h e r y products, excessive cold storage causes toughening of the t i s s u e s (3) (11). Another major factor a f f e c t i n g texture, and thus the a c c e p t a b i l i t y of cooked f i s h , i s the post mortem pH. The lower the pH, the tougher the f l e s h (3). In s p i t e of the e f f e c t s of cold storage on f i s h q u a l i t y , how f i s h are handled from the time of harvesting dramatically a f f e c t s p a l a t a b i l i t y . Countries such as Norway and Iceland have s t r i c t handling procedures, mandated by law, which has


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contributed t o t h e i r reputation for q u a l i t y groundfish. Dramatic improvements i n appearance, y i e l d , shelf l i f e , texture and o v e r a l l q u a l i t y have been reported after comparisons have been made between groundfish bled and boxed a t sea and groundfish handled and stored i n the t r a d i t i o n a l manner. Advances i n maintaining seafood q u a l i t y are now allowing Iceland and Norway t o ship fresh f i s h d i r e c t l y into the U.S. market and s e l l i t for a premium p r i c e . U.S. producers w i l l have t o make changes i n their methods i n order t o avoid invasion from foreign markets (12). Not every f i s h i n g system works as w e l l and preserves f i s h as long as the ones used i n Iceland and Norway. Spoilage a t sea i s very common and contributes s u b s t a n t i a l l y t o the l o s s of f i s h e r y resources. Several f a c t o r s a f f e c t the keeping q u a l i t y of f i s h held on trawlers. One factor i s the temperature of the water from which the catch i s taken. F i s h from high temperature water needs l e s s c h i l l i n g t o i n h i b i t enzyme a c t i v i t y ; f i s h from very low temperature waters need very low temperature c h i l l i n g to retard enzyme a c t i v i t y (13). Aside from the complications imposed by the o i l i n f i s h and the need t o keep the catch cold, there i s a l s o a compound i n f i s h c a l l e d trimethylamine oxide (TOAD), which i s converted t o trimethylamine (TMA). Trimethylamine oxide i s e s s e n t i a l l y an odorless compound which i s converted by b a c t e r i a i n and on the f i s h t o the f i s h y t a s t i n g and smelling compound, trimethylamine. Retarding t h i s conversion i s one of the prime objectives of adequate cold storage of f i s h e r y products (3) (8).

CQHSUrption Japan and Russia are the two most aggressive countries i n the f i e l d of large-scale f i s h i n g ; Japan a l s o has the highest per capita consumption of f i s h . The United States i s a r e l a t i v e l y small consumer of f i s h e r y products, with 50 t o 60% of the f i s h consumed being imported. On a per capita basis, Americans consumed 11.4 pounds of edible weight of f i s h products i n 1970 — l e s s than one-fourth the amount of poultry consumed (11). In the United States, almost h a l f of the f i s h consumed i s fresh or frozen; the other h a l f i s canned. Of the nearly 200 commercial species of f i s h , most consumers are f a m i l i a r with fewer than twenty (11). Tuna i s by far the most popular f i s h consumed i n the United States. In recent years, Americans have eaten an average of three pounds or more of canned tuna per capita. Tuna accounts for almost one-fourth of the t o t a l of a l l species of f i s h and s h e l l f i s h consumed i n the United States (14).


higgins a n d kolbye


One out of every three f i s h f i l l e t s or steaks eaten i n the United States i s cod. Other popular f i s h are flounder and other turbot which comprise another 20% of consumption. About 15% of t o t a l consumption consists of haddock or pollock. Salmon ranks fourth i n o v e r a l l consumption behind tuna, shrimp and cod (14). f

On a worldwide basis, a f i f t h of the t o t a l catch of f i s h and s h e l l f i s h has been of sea herring and pilchards. The catch has been increasing over the years and i n 1979 i t exceeded 34 b i l l i o n pounds — more than the catch of cods, tunas or any other group of f i s h (14). Most of the pilchards and h e r r i n g - l i k e f i s h nourish man i n d i r e c t l y . These f i s h are mainly used as f i s h meal which i s used, i n turn, t o feed poultry and livestock, e s p e c i a l l y pigs (15).

mm

Catch

About 90% of the world catch comes from oceans, seas and t r i b u t a r i e s . Rivers, lakes and other bodies of fresh water provide the remainder of the supply (11). World production of aquatic l i f e , excluding whale, doubled twice i n the decades between 1950 and 1970. Growth i n world f i s h e r y production throughout the seventies, however, was lower than the rate of growth i n population. Consequently, on a worldwide basis, the contribution of f i s h t o human n u t r i t i o n has declined (16). There i s a l i m i t t o the amount of f i s h which can be caught before the supply i s seriously compromised. The s t a b i l i z a t i o n and, indeed, decline i n some species of the world catch i n the past decade i s l a r g e l y due t o the diminishing number of stocks of conventional f i s h . The l i m i t of future production l i e s between four and ten times the present harvest. Part of t h i s increase w i l l come from increased f i s h i n g , but possibly f i f t y percent w i l l be achieved only through better management of t h i s renewable natural resource (16). There i s no doubt that for much of the world population f i s h are the main source of animal protein. Twenty years ago, i t was thought that increasing the world catch would solve the world's animal protein problem. More r e a l i s t i c projections currently show that the stock may not meet the demand, e s p e c i a l l y i n developing countries. The thought today i s that better management, such as through technological advances, i s needed t o take the s t r a i n o f f the catch and make better use of f i s h end-products (16).


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One such suggestion i s to turn f i s h materials now being used f o r animal feed and f e r t i l i z e r into palatable human food, instead. Since f i s h s p o i l rapidly, much of the world catch becomes u n f i t f o r human consumption, but freezing f i s h and f i s h products conserves f i s h which otherwise would have been wasted and i t allows greater d i s t r i b u t i o n . This technology, however, i s r e l a t i v e l y expensive for most consumers of the world (8). Aquaculture i s another means of meeting the demand f o r f i s h e r y products. This method, however, i s rather c o s t l y i n developed nations, although many countries have practiced some form of aquaculture for many years. China practiced f i s h farming as f a r back as 2000 B.C., but i t was introduced only recently i n A f r i c a where about 700,000 tons are produced annually. F i s h farming has maintained i t s importance through the centuries i n Russia, which today produces about 200,000 tons of pond f i s h (17). Although aquaculture can be costly, one of the l e a s t c o s t l y and most productive species i s the pond-raised c a t f i s h . Most c a t f i s h ' require a l i v i n g organism for food, but the channel c a t f i s h w i l l eat almost anything and can grow as large as twenty pounds (18). As yet, only about 30% of the U.S. consumers have ever tasted c a t f i s h , but with increased production and greater consumer awareness, t h i s figure i s sure to r i s e (19). C a t f i s h are not the only species suitable f o r aquaculture. Bass, trout, prawns and salmon are successfully being c u l t i v a t e d for human consumption (18).

Risks of Consuming Seafood Risks to the consumer from seafood can come from either n a t u r a l l y occurring b a c t e r i o l o g i c a l contaminants or manmade environmental contamination. Type E Clostridium botulinum i s one microbiological contaminant which i s appearing more frequently i n f i s h e r y products. Most botulism outbreaks have been traced to foods that have been poorly processed and held i n an anaerobic environment conducive to Clostridium botulinum growth. I t i s worthy of note that fresh or frozen f i s h e r y products h i s t o r i c a l l y never have been implicated i n outbreaks of botulism among humans (2 0). The smoked f i s h industry was responsible for several botulism outbreaks i n the 1960's, but i t has produced m i l l i o n s of pounds of safe products since that time after processing techniques were modified (21).


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Some of the other organisms which cause major health problems around the world and which are found i n seafoods are d i p h y l l o b o t h r i a s i s a n i s a k i a s i s , heterophyiasis and chlonorchiasis. These i n f e c t i o u s organisms can be retarded or controlled by precautionary storage and preparation techniques (22). f

V i b r i o cholerae outbreaks have occurred on occasion i n the United States among persons eating seafoods. Although the dangers from t h i s organism are not a t c r i t i c a l proportions, there i s some concern that the contamination might become more widespread unless preventive measures are taken (17) (20) (23). A toxicant worthy of note i s one which occurs p r i m a r i l y i n Caribbean f i s h e s and i s known as ciguatera toxin. As many as three hundred types of f i s h e s from the Caribbean and equatorial regions of the P a c i f i c Ocean have been found t o contain t h i s toxin (15). Environmental contamination i s another source of concern, not only f o r the safety of the consumer, but a l s o f o r the f i s h i n g industry because of the p o t e n t i a l cost t o marine l i f e as w e l l as t o human l i f e (20) (24). Since the l a t e 1960's problems related t o contamination of f i s h and s h e l l f i s h have been recognized. The problem compounds share one c h a r a c t e r i s t i c : biopersistence. Compounds such as various s a l t s of lead or mercury have contaminated s h e l l f i s h or f i s h l i v i n g i n either fresh or s a l t water. Chlorinated compounds such as DDT, PCB and dioxins have been found i n f i s h l i v i n g i n fresh water r i v e r s and lakes and t o some extent i n the B a l t i c and Mediterranean Seas (25). In more recent years, e f f o r t s have been stepped up t o control environmental p o l l u t i o n , with the r e s u l t that i n many areas residues of such compounds i n f i s h and s h e l l f i s h are decreasing s u b s t a n t i a l l y from previous l e v e l s . The chlorinated compounds mentioned e a r l i e r have the a b i l i t y at sustained high doses i n rodents t o promote the development of l i v e r cancer; thus, they have been c a l l e d "carcinogenic." When viewed i n terms of projected hazards t o human health, however, human exposure i s usually low l e v e l and sporadic. Most of the detectable l e v e l s of chlorinated compounds i n various f i s h and s h e l l f i s h pose no hazard t o human health. In summary, from the standpoint of r i s k s and benefits, the benefits f a r outweigh the r i s k s . There are many health benefits to be der ived from eating f i s h and s h e l l f i s h as long as the n u t r i t i o n a l q u a l i t y i s assured. Seafood and fresh water f i s h , as well as s h e l l f i s h , are excellent foods. They are a renewable


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SEAFOOD TOXINS natural resource which can feed many who are hungry. Some obstacles t o the r e a l i z a t i o n of f i s h e r y products f u l l p o t e n t i a l revolve around production, spoilage and d i s t r i b u t i o n problems. There are many i n d i v i d u a l s and organizations, as w e l l as the federal government, who are cooperating t o ensure that the p u b l i c safety i s secure. The greatest threat t o the p u b l i c health i s from b i o l o g i c a l toxins and i n f e c t i o n s as opposed t o chemical toxins, but greater attention should be given t o c o n t r o l l i n g environmental contamination. 1

Literature Cited 1. 2. 3. 4. 5.

6. 7. 8. 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19.

Anthony, J . E . , ; Hadgis, P.; Milam, R.; Herzfeld, G.; Taper, L.; Ritchey, S. J. Food S c i . 1983, 48, 313-314. Fox, B. "Food Science - A Chemical Approach;" Hodder and Stoughton: London, 1978; p. 210-211. Love, R. In "Advances in Fish Science and Technology;" Connell, J . J . , Ed; Fishing News Books Ltd.: Surrey, England, 1979; p. 130-138. "Teacher's Manual. Fishery Products Inspection," U.S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service. Stillings, B.; "Thompson, M. "Seafoods and Health," Fishery Market Development Series No. 17; U. S. Department of Commerce, National Oceanic and Atmospheric Administration, National Marine Fisheries Service. Carpenter, K. In "Advances in Fish Science and Technology;" Connell, J . J . , Ed; Fishing News Books Ltd.: Surrey, England, 1977; p. 124-130. Gunby, P. J. Amer. Med. Assoc. 1982. 247, 729-731. Suzuki, T. "Fish and K r i l l Protein: Processing Technology;" Applied Science Publishers Ltd.: London, 1981. R o n s i v a l l i , L. J.; Gorga, C.; Kaylor, J.; Carver, J.; Mar. Fish Rev. 1978, 1, 1-4. Khayat, Α.; Schwall, D.; Food Tech. 1983. 37, 130-140. V a i l , G.; P h i l l i p s , J.; Rust, L . ; Griswold, R.; Justin, M. "Foods - An Introductory College Course;" Houghton-Mifflin Company: Boston, 1973. Sackton, J . Sea. Bus. Rep. 1982, 80, 57-60. Hansen, P.; Jensen, J . Infofish Mkt. Dig. 1982. 6, 26-28. Slavin, J . "Fish Facts;" Food Marketing Institute: Washington, D.C., 1982. Chichester, C., personal communication. Robinson, M. "Prospects for World Fisheries to 2000;" Food and Agriculture Organization of the United Nations: Rome, 1982, June, 1-16. Kreuzer, R. In "Fishery Products;" Fishing News Ltd: Surrey, England, 1974, 22-47. Hopkins, H; FDA Cons. 1981, 15, 10-15. Food Eng. 1982, 54, 151.


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20. Finch, R. In "Fishery Products;" Fishing News Ltd: Surrey, England, 1974, 53-59. 21. Eklund, M.W. Food Tech. 1982, 36, 107-112. 22. Asner, M. FDA Cons. 1982, 16, 4-7. 23. De Paola, A. J. Food Sci. 1981, 46, 66-70. 24. "Interchange of Pollutants between the Atmosphere and the Oceans," Reports and Studies No. 13, World Meteorological Organization, 1981. 25. "The Review of the Health of the Oceans," Reports and Studies No. 15, United Nations Educational, Scientific and Cultural Organization, 1981. RECEIVED April 23, 1984


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Risks and Benefits of Seafood - ACS Publications - American

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