Posted by Larry Hoover on November 24, 2002, at 14:15:16
In reply to Re: Thank you Larry, for your input. I'm going to » Larry Hoover, posted by disney4 on November 24, 2002, at 13:32:36
> Hi Larry,
> I have another question for you about fish oil. In the link to the Bipolar Child there is some mention about cell membranes becoming stiff when people eat a diet high in trans fatty acids and take fish oil. I am not careful about my diet, and would hate to think I am doing more harm than good by taking fish oil.
> The Diet of the Child is of Utmost Importance. Parents need to look not only to capsules, however, but to the total diet of their children. Because, as we said earlier, other lipids compete in the cell membranes for the spots that the omega-3's would occupy, a diet high in fat and trans-fatty acids will interfere with omega-3 integration in the cell membrane and the membranes will become stiff and inflexible.
I take it that the latter paragraph is a quotation? I see it as a comparison of taking fish oil *or* consuming trans fatty acids.
Trans fats, although they are unsaturated, have a different three-dimensional structure that do cis fats. Trans fats condense at a higher tremperature than do cis ones. We see that as trans fats solidifying at room temperature, whereas cis fats remain liquid, often even under refrigeration.
An unsaturated fat has carbon-carbon double bonds. If there is only a single bond, each carbon is free to rotate about the axis of the bond. However, a double bond is rigid, pinning the orientation of the carbons.
Because the single bonds of a saturated carbon chain can reorient themselves, they can line up in neat rows beside other chains. When they do that, they stop moving around, and the fatty acids are said to condense, or solidify.
Trans fatty acids aren't very much different than saturated fatty acids in the overall orientation of the carbon chain, and they also solidify fairly readily.
Cis fats have a kink in the long carbon chain, sending the chain off at a 120 degree angle. If there's more than one cis bond, there's more than one kink. The "kinkier" a fatty acid is, the harder it is for it to align with other fatty acids and come to rest in a solid form.
Neuronal membranes depend on the long-chain polyunsaturated fatty acids like DHA and AA for their fluid nature, because the kinky fatty acids cannot condense. If your brain only has trans fatty acids available when it comes time to replace membrane constituents, then that's what it will use, but the membranes will be stiffer, or less fluid, as a result.
Part of the mechanism by which neurotransmitters dock at membrane receptors requires the membrane to be quite flexible. A stiffer membrane has the effect of reducing the signal arising from a particular amount of a neurotransmitter; it's as if there is a deficiency in the neurotransmitter itself.
It's been estimated that the daily turnover rate for membrane fats is no more than 3%. For technical reasons, it is an exponential relationship between supply of DHA and DHA replacement in the membrane, but it might take four months (ballpark) of fish oil supplementation to get the brain replenished in the necessary omega-3 fatty acids.