6 Safe and Nutritious Aquaculture Produce
203
A very similar situation was seen in sea bass where 200 g of flesh, from fish
grown on FO diets, can provide 29% of the ISSFAL weekly recommended intake
(3.5 g) of EPA + DHA and around 690 g/week would be needed to fully meet the
ISSFAL recommendation. As with bream, just over 1 kg of sea bass grown on 60%
VO would meet the ISSFAL weekly intake value for EPA + DHA (Fig. 6.5).
Following a FO finishing diet period 570 g of sea bass fed FO would supply the
weekly intake value or 740 g of sea bass fed 60% VO would meet the recommended
EPA + DHA intake value (Fig. 6.5). In contrast to bream, but similar to salmon and
trout, the concentrations of EPA + DHA increase in the post-finishing diet period.
This is due to a lower lipid deposition, seen in larger fish, in bass compared to
bream (Mourente et al. 2005; Izquierdo et al. 2005).
While these results clearly demonstrate that fish with oily flesh, such as salmon
and trout, can provide a higher dietary intake of EPA and DHA, compared with
leaner fish, the contribution of beneficial fatty acids from the leaner species is still
significant. Even in very lean white fish species, such as cod and plaice, where flesh
lipid values may only be 1% of wet weight, the EPA + DHA content of ~0.25 g/100 g
can still make an important contribution to the human diet (SACN/COT 2004;
EFSA 2005). This is especially important as the HUFA in lean fish are concentrated
in the phospholipid fraction which is thought to be more easily digested and deposited in cell membranes than HUFA supplied as triglyceride oils. For this reason, the
advice of the UK Food Standards Agency that we should consume two portions of
fish per week, of which one should be lean and the other oily, is sound nutritional
advice (www.food.gov.uk).
6.7 Health Benefits of Consuming Fish Protein
In addition to the widely documented benefits of the n-3 HUFA, found in fish oils,
there is also considerable evidence to support the role of fish protein, peptides and
amino acids as valuable nutrients for animal and human health, especially
cardiovascular health. Feeding rats cod protein reduced hepatic triacylglycerol
(TAG) concentrations and reduced TAG secretion rates compared to rats fed casein
(Demonty et al. 2003) while a mixture of cod protein and menhaden oil resulted in
50% lower plasma TAG compared to rats fed casein and beef tallow (Demonty
et al. 2003). In rats fed fish, soybean or casein as protein source, the plasma
cholesterol concentrations were reduced for fish and soya compared to casein
(Iritani et al. 1985) while the former two also increased excretion of bile salts and
cholesterol in faeces. In another study, feeding fish protein to rats, rabbits and humans
resulted in reduced plasma cholesterol concentrations in all cases (Jacques 1990). In
addition, feeding cod and soy proteins resulted in lower fasting plasma glucose
and insulin levels, in rats, compared to those fed casein (Lavigne et al. 2000). Fish
protein has also been shown to affect blood coagulation by increasing fibrinolysis
in rats (Murata et al. 2004).
203
A very similar situation was seen in sea bass where 200 g of flesh, from fish
grown on FO diets, can provide 29% of the ISSFAL weekly recommended intake
(3.5 g) of EPA + DHA and around 690 g/week would be needed to fully meet the
ISSFAL recommendation. As with bream, just over 1 kg of sea bass grown on 60%
VO would meet the ISSFAL weekly intake value for EPA + DHA (Fig. 6.5).
Following a FO finishing diet period 570 g of sea bass fed FO would supply the
weekly intake value or 740 g of sea bass fed 60% VO would meet the recommended
EPA + DHA intake value (Fig. 6.5). In contrast to bream, but similar to salmon and
trout, the concentrations of EPA + DHA increase in the post-finishing diet period.
This is due to a lower lipid deposition, seen in larger fish, in bass compared to
bream (Mourente et al. 2005; Izquierdo et al. 2005).
While these results clearly demonstrate that fish with oily flesh, such as salmon
and trout, can provide a higher dietary intake of EPA and DHA, compared with
leaner fish, the contribution of beneficial fatty acids from the leaner species is still
significant. Even in very lean white fish species, such as cod and plaice, where flesh
lipid values may only be 1% of wet weight, the EPA + DHA content of ~0.25 g/100 g
can still make an important contribution to the human diet (SACN/COT 2004;
EFSA 2005). This is especially important as the HUFA in lean fish are concentrated
in the phospholipid fraction which is thought to be more easily digested and deposited in cell membranes than HUFA supplied as triglyceride oils. For this reason, the
advice of the UK Food Standards Agency that we should consume two portions of
fish per week, of which one should be lean and the other oily, is sound nutritional
advice (www.food.gov.uk).
6.7 Health Benefits of Consuming Fish Protein
In addition to the widely documented benefits of the n-3 HUFA, found in fish oils,
there is also considerable evidence to support the role of fish protein, peptides and
amino acids as valuable nutrients for animal and human health, especially
cardiovascular health. Feeding rats cod protein reduced hepatic triacylglycerol
(TAG) concentrations and reduced TAG secretion rates compared to rats fed casein
(Demonty et al. 2003) while a mixture of cod protein and menhaden oil resulted in
50% lower plasma TAG compared to rats fed casein and beef tallow (Demonty
et al. 2003). In rats fed fish, soybean or casein as protein source, the plasma
cholesterol concentrations were reduced for fish and soya compared to casein
(Iritani et al. 1985) while the former two also increased excretion of bile salts and
cholesterol in faeces. In another study, feeding fish protein to rats, rabbits and humans
resulted in reduced plasma cholesterol concentrations in all cases (Jacques 1990). In
addition, feeding cod and soy proteins resulted in lower fasting plasma glucose
and insulin levels, in rats, compared to those fed casein (Lavigne et al. 2000). Fish
protein has also been shown to affect blood coagulation by increasing fibrinolysis
in rats (Murata et al. 2004).