Fish protein hydrolysate reduces plasma total cholesterol an increases the proportion of HDL cholesterol in rats

Here's an interesting fish protein study with rats:

Wergedahl H, Liaset B, Gudbrandsen OA, Lied E, Espe M, Muna Z, Mork S,
Berge RK.
Fish protein hydrolysate reduces plasma total cholesterol, increases
the proportion of HDL cholesterol, and lowers acyl-CoA:cholesterol
acyltransferase activity in liver of Zucker rats.
J Nutr. 2004 Jun;134(6):1320-7.
PMID: 15173391 [PubMed - indexed for MEDLINE]
<http://jn.nutrition.org/cgi/content/full/134/6/1320>

"There is growing evidence that soy protein improves the blood
lipid profiles of animals and humans. We compared the effects
of fish protein hydrolysate (FPH), soy protein, and casein
(control) on lipid metabolism in Wistar rats and genetically
obese Zucker (fa/fa) rats. In Zucker rats, FPH treatment
affected the fatty acid composition in liver, plasma, and
triacylglycerol-rich lipoproteins. The mRNA levels of Delta 5
and Delta 6 desaturases were reduced by FPH and soy protein
feeding compared with casein feeding. In Zucker rats both FPH
and soy protein treatment reduced the plasma cholesterol level.
Furthermore, the HDL cholesterol:total cholesterol ratio was
greater in these rats and in the Wistar rats fed FPH and soy
protein compared with those fed casein. Although fecal total
bile acids were greater in soy protein-fed Zucker rats than in
casein-fed controls, those fed FPH did not differ from the
controls. However, the acyl-CoA:cholesterol acyltransferase
activity was reduced in Zucker rats fed FPH and tended to be
lower (P = 0.13) in those fed soy protein compared with those
fed casein. Low ratios of methionine to glycine and lysine to
arginine in the FPH and soy protein diets, compared with the
casein diet, may be involved in lowering the plasma cholesterol
concentration. Our results indicate that the effects of FPH and
soy protein on fatty acid metabolism are similar in many
respects, but the hypocholesterolemic effects of FPH and soy
protein appear to be due to different mechanisms. FPH may have
a role as a cardioprotective nutrient."

[...]

In summary, although the effect of soy protein on lipid
metabolism generally was slightly more pronounced than that of
FPH, the cardioprotective effect of FPH was clearly
demonstrated. The mechanism for the cholesterol-lowering effect
of FPH is different from that of soy protein because FPH
lowered plasma cholesterol in Zucker rats by reducing the
activity of ACAT, whereas soy protein did so by also affecting
the secretion of fecal bile acids.

--
Matti Narkia
.

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