Re: how much dha in sardines?
You had better hope there isn't much, if you are eating them.
"...addition of cod liver oil to to the diet elevated the rate of
peroxidation by 20-fold."
And that was on top of the 10-fold increase over rats on the fat free
diet (when corn oil was added.
Source: from the text of the following:
Free Radic Biol Med. 1988;5(2):95-111.
A role for dietary lipids and antioxidants in the activation of
Division of Comparative Medicine, Clinical Research Centre, Harrow,
The ways in which dietary polyunsaturated fats and antioxidants affect
the balance between activation and detoxification of environmental
precarcinogens is discussed, with particular reference to the
polycyclic aromatic hydrocarbon benzo(a)pyrene. The structure and
composition of membranes and their susceptibility to peroxidation is
dependent on the polyunsaturated fatty acid (PUFA) content of the cell
and its antioxidant status, both of which are determined to a large
degree by dietary intake of these compounds. An increase in the PUFA
content of membranes stimulates the oxidation of precarcinogens to
reactive intermediates by affecting the configuration and induction of
membrane-bound enzymes (e.g., the mixed-function oxidase system and
epoxide hydratase); providing increased availability of substrates
(hydroperoxides) for peroxidases that cooxidise carcinogens (e.g.,
prostaglandin synthetase and P-450 peroxidase); and increasing the
likelihood of direct activation reactions between peroxyl radicals and
precarcinogens. Antioxidants, on the other hand, protect against lipid
peroxidation, scavenge oxygen-derived free radicals and reactive
carcinogenic species. In addition some synthetic antioxidants exert
specific effects on enzymes, which results in increased detoxification
and reduced rates of activation. The balance between dietary
polyunsaturated fats, antioxidants and the initiation of carcinogenesis
is discussed in relation to animal models of chemical carcinogenesis
and the epidemiology of human cancer.
Biochemist Ray Peat has cited much older studies, such as how dogs fed
fish oil all died of cancer:
"Fifty years ago, it was found that a large amount of cod liver oil in
dogs' diet increased their death rate from cancer by 20 times, from the
usual 5% to 100%. A diet rich in fish oil causes intense production of
toxic lipid peroxides, and has been observed to reduce a man's sperm
count to zero. [H. Sinclair, Prog. Lipid Res. 25, 667, 1989.]"
Stop listening to the hype (mostly from people who want to sell you
supplements) and start doing your own thinking and research!