Fatty fish

Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) are omega-3 polyunsaturated fatty acids that are most abundant in fatty fish such as sardines, salmon, and mackerel. A diet high in EPA plus DHA or supplementation with these fish oils reduces the risk of cardiovascular mortality, reinfarction, and stroke in patients who have experienced an MI. 

A final point is that in laboratory studies reducing lipid content of rainbow trout by starvation did not increase whole body PCB elimination (24). Instead PCB concentration in body fat increased as the absolute amount of fat in the fish decreased (24). The latter has also been shown in coho salmon (33). Thus, reducing body fat by starvation does not appear to be a very effective way of increasing PCB elimination in fatty fish. 

The RDl for vitamin D is 5 micrograms/day for men and women, adults and children, a value independent of state of pregnancy or lactation. Middle-aged adults, ages 50-70 years old, require 10 micrograms/day and for those over 70 years old the valne goes np to 15 micrograms/day. Fish oils, the flesh of fatty fish, and fortified milk and cereals are excellent sources of vitamin D. Of course, vitamin D is also present in most multivitamin piUs. 

Pattaravivat, J., Morioka, K., Shirosaki, M., and Itoh, Y. (2008). Effect of washing conditions on the removal of lipid from the fatty fish escolar (Lepidocybium flavobrunneum) meat. ]. Biol. Sci. 8, 34-42. 

Vitamin D is converted in the liver and kidneys to 1,25-dihydroxyvitamin D, which is the hormone-active compounds. The principal physiological function is to maintain the serum calcium and phosphorus concentrations in a range that support cellular processes, neuromuscular function, and bone ossihcation [417], Only a few foods contain vitamin D in quantities that have an impact on the dietary intake hsh liver, hsh liver oils, fatty fish, and egg yolks. Thus, some countries practice fortihcation of certain foods with vitamin D, most often milk, margarine, and/or butter. 

Fat is a key component in the human diet. Research shows that excessive consumption of saturated fat negatively impacts several biomarkers of health while monounsaturated and n-3 PUFAs are beneficial to human health. Moreover, research shows that imbalanced dietary ratios of n-6 n-3 may lead to various health complications as well as disease progression while increased n-3 levels impart prevention and health promoting effects (Burghardt et al., 2010 Goodstine et al., 2003 Simopoulos, 2002 Wan et al., 2010). The American Heart Association recommends eating fatty fish meals at least twice a week due to their promising health and especially cardiovascular benefits. Here, we review some of the health benefits of n-3 PUFAs, due in part to their anti-inflammatory effects in cancer, cardiovascular diseases (CVDs), obesity, and other metabolic disorders. 

Thyroid Effects. Limited information is available on thyroid effects in PBDE-exposed humans. There are suggestive occupational data as shown by effects that included increased serum FSH, low or borderline low serum T4, and increased thyroid antimicrosomal antibody titers in workers exposed to decaBDE and/or unspecified PBBs. There was no clear association between plasma levels of 2,2, 4,4-tetraBDE and thyroid hormone levels (free and total T3 and T4, TSH, free testosterone, follicle-stimulating hormone, lutenizing hormone, and prolactin) in men who consumed varying amounts of fatty fish from the Baltic Sea. Based on consistent evidence in animals, as summarized below, the thyroid is particularly sensitive to PBDEs and is a likely target of toxicity in exposed humans. 

Relatively few foods contain significant amounts of vitamin D. In addition to conversion in situ by the body, the principal sources of vitamin D are foods derived from animal sources, including egg yolk, fatty fish and liver. Unfortified cows milk is not an important source of vitamin D. 

Vitamin D occurs naturally in fatty fish, liver, and egg yolk. Milk, unless it is artificially fortified, is not a good source of the vitamin. The RDA for adults is 5 mg cholecalciferol, or 200 international units (IU) of vitamin D. 

The addition of smoke to meat also imparts antioxidant properties (42). This has also been shown on application of smoke to fatty fishes (43). Porter ( 6) has reviewed the antioxidant properties of smoke and concluded that a number of phenolic compounds are responsible. Several of these phenolic components, including phenol, guaiacol and catechol, are not only potent antioxidants but also have antibiotic activity. 

It is found in fortified milk and butter, egg yolks, fatty fish and fish-liver oils. It is also made by... 

Lignans Inhibit estrogen and block prostaglandins Fatty fish, flaxseed, walnuts... 

This period is also marked by the deposition of energy substrates - mostly triacyl-glycerols in fatty fish and liver glycogen in lean fish. The rate of accumulation is much lower than that of protein production (O Boyle and Beamish, 1977), a fact explicable from the life strategy of the fish they must attain maximum size and weight as soon as possible before becoming sexually mature, so as to be able to escape predators, to search effectively for food and to evolve optimum reproductive power. Fecundity is directly proportional to... 

The Atlantic cod offers an example (in a non-fatty fish) of extreme proportions of phospholipids and triacyl-glycerols. As much as 88% of the lipids of the white muscle (total lipid content 0.5% to 0.6%) consists of phospholipids and only about 1% is triacyl-glycerols. When the fish are starved, the minute proportion of triacyl-glycerols does not change, so in this situation a... 

Muravskaya, 1978 Diana and Mackay, 1979 Shatunovsky, 1980). However, in all starved fish it is the lipid that is mobilized first, except possibly in the eel. In fatty fish, much lipid is used from the flesh, while in lean fish it is used from the liver. In both types of fish, muscle protein is mobilized only when the lipid resources fall below a critical level. Black and Love (1986) showed that energy substrates are mobilized in a definite sequence, white muscle protein, for example, being metabolized at an earlier stage than red muscle protein, while, on refeeding, the latter is replenished before the former. 

However, the sequence of mobilization must always be borne in mind, lipids being mobilized before the contractile muscle is raided in many species of non-fatty fish, large resources of lipid are in fact stored in the liver. Pickerel take up an intermediate position, lipid and protein being removed equally from the flesh. 

Laboratory experiments showed that the water content of the muscle of small, immature cod subjected to starvation rose (reflecting protein depletion) from 80% to around 86%, beyond which level the fish died. Larger fish, however, which had spawned several times, could be depleted until the water content of the musculature was over 95% - a remarkable adaptation to the more severe depletion imposed under natural conditions (Love, unpublished). While this phenomenon differs from that described above in fatty fish, it again illustrates a change in the metabolism of fish in response to growth. Likewise, Borisov and Shatunovsky (1973) studied the possibility of using the water content to estimate the natural mortality rate of Barents Sea cod. 

Since the liver changes markedly in size according to its lipid content, the most useful measure is the quantity of lipid in the whole liver, rather than the concentration in a piece of the organ. Where much lipid is stored, the liver is large and creamy in appearance, while the liver of a starved fish is small and red. It must be emphasized that this particular scheme applies only to nonfatty fish, which store virtually all their lipid reserves in their livers. Fatty fish will behave somewhat differently, although die general principles are the same. 

In fatty fish, the total lipid content correlates negatively with the content of dry matter and water. The fat-water line has been recognized in dozens of species of fish (Kizevetter, 1942 Levanidov, 1950 Luhmann, 1953, 1955 Brandes and Dietrich, 1958 Krivobok and Tarkovskaya, 1960 Shulman, 1961). The correlation is a good one (r=-0.8 to -0.9), but each species has its own equation. In Black Sea sprat, for example, the relationship is Y=-13.28 + 0.84X, where Y is the total lipid content and X the content of dry matter... 

Such an approach was developed independently by the authors and their colleagues, who were prevented by international problems from becoming fully aware of one another s progress. With the introduction of openness in the former Soviet Union, it has been possible for the authors to meet and engage in full collaboration. This volume offers insight into hitherto inaccessible Russian data that concern principally the fatty fish and their lipid dynamics to this is added complementary western studies on non-fatty fish, especially their proteins. 

In the absence of inadequate endogenous synthesis, vitamin D must be obtained from dietary sources or from supplements. Few foods contain vitamin D except for the flesh of fatty fish (salmon, mackerel, sardines), fish liver oils, and eggs from hens fed feed enriched with vitamin D. In the United States, all commercially produced milk is fortified with vitamin D2 at a level of 400 IU/L (1 IU = 0.025 fig of vitamin D3). Therefore, in the United States (and other economically advanced countries) most dietary vitamin D is obtained from milk and other vitamin D2-fortified foods. Both vitamin D2 and vitamin D3 are converted at the same rate to 25-hydroxyvitamin D by a hydroxylase in the liver and are equally active as a prohormone. Because dietary uptake of vitamin D is dependent on normal fat absorption, conditions in which fat malabsorption is present can result in vitamin D deficiency. Because breast milk contains little vitamin D, vitamin D deficiency can occur in infants who are solely breastfed, are not exposed to adequate sunlight, and are not receiving vitamin D supplements. The adequate intake of vitamin D for children is 5 pg/day (200 IU/day) (Table 30-2). 

The study by Hites et al. (2004) of BDEs in farmed and wild salmon promoted discussions regarding the consumption of fatty fish. The health benefits of omega-3 fatty acids are clear, but the consumption of (especially) farmed fish exposes consumers to higher intakes of lipophilic contaminants (including BDEs) and so presumably to an additional health risk (Law et al, 2006a). The development of less contaminated feeds for use in salmon farms may be a way of reducing this risk. 

Numerous studies document PCBs in food suppfies as seen from the perspective of human exposure (Davies, 1988 Schecter and Piskac, 2001). Due to their hydrophobicity, PCB concentrations track closely concentrations of fat and lipids, resulting in foods rich in animal lipids, such as fatty fish, cheese and meats, having the highest concentrations, as seen in Figure 8.4 (e.g. Watanabe et al, 1979 Wilson et al, 2003 Schaeffer et al, 2006 Koizumi et al, 2005). 

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