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Dr. Bob is Robert Hsiung, MD,
bob@dr-bob.orgShown: posts 1 to 18 of 18. This is the beginning of the thread.
Posted by nilla on November 25, 2002, at 11:16:31
Fish Oil Vs. Flaxseed. what's the difference? (nm)
Posted by Larry Hoover on November 25, 2002, at 11:28:36
In reply to Fish Oil Vs. Flaxseed. what's the difference? (nm), posted by nilla on November 25, 2002, at 11:16:31
> Fish Oil Vs. Flaxseed. what's the difference? (nm)
Flax seed oil contains a precursor to the fatty acids found in fish oil. Your body cannot use the flax oil directly. It has to do a conversion. Fish oil goes straight to work.
Flaxseed oil contains alpha-linolenic acid, a polyunsturated fatty acid that is eighteen carbons long, and three-times unsaturated. The short-form is 18:3 n-3. The latter term signifies that it is an omega-3 fatty acid.
Fish oil contains two polyunsaturated acids that are important. They are EPA, which is 20:5 n-3, and DHA, which is 22:6, n-3.
You can see that both EPA and DHA are longer, and more unsaturated than the 18:3 in flaxseed oil. The conversion requires step-by-step activity of different enzymes. Some people do the conversion so poorly that there is zero output of DHA from ALA. The average is about 3-6%. Other dietary factors influence the conversion, like the amount of vegetable oil in the diet (inhibitory influence).
Fish oil gives you the good stuff, for sure. Flaxseed oil might.
Posted by kara lynne on November 25, 2002, at 12:28:40
In reply to Re: Fish Oil Vs. Flaxseed. what's the difference?, posted by Larry Hoover on November 25, 2002, at 11:28:36
Posted by Larry Hoover on November 25, 2002, at 13:22:58
In reply to What about evening primrose or borage oil? (nm), posted by kara lynne on November 25, 2002, at 12:28:40
Evening primrose, borage, and black currant oils are good sources of GLA (gamma-linolenic acid).
I know the terminology is confusing. Both ALA (alpha-linolenic) and GLA (gamma-linolenic) are 18:3, but the difference has to do with where one of the unsaturated bonds is. ALA is an omega-3. GLA is an omega-6.
In the presence of fish oil or ALA, competetive influences at the enzyme level pushes more of the GLA towards type one prostaglandin synthesis. PG-1 is associated with elevated mood, and reduced inflammatory response. In the absence of omega-3 fats, much more of the GLA goes towards arichidonic acid (20:4, omega-6), and type 2 prostaglandins. PG-2 is associated with enhanced inflammation. High arichidonic acid levels are also associated with depressed mood through neuronal membrane changes (reduced fluidity).
Posted by kara lynne on November 25, 2002, at 13:29:43
In reply to Re: What about evening primrose or borage oil?, posted by Larry Hoover on November 25, 2002, at 13:22:58
I'm still trying to understand; so are you saying that Evening Primrose or Borage oil alone could lead toward increased inflammation and depressed mood, or did I read incorrectly? I'm looking for alternatives to fish oil, which as you've read, makes me sick. Thanks for your patience and knowledge.
Posted by Larry Hoover on November 25, 2002, at 13:37:19
In reply to Re: What about evening primrose or borage oil?, posted by kara lynne on November 25, 2002, at 13:29:43
> I'm still trying to understand; so are you saying that Evening Primrose or Borage oil alone could lead toward increased inflammation and depressed mood, or did I read incorrectly?
That's a possibility, if you do not have sufficient omega-3s to modulate what happens to this particular omega-6. Dr. Weil notes this in his books, for example.
>I'm looking for alternatives to fish oil, which as you've read, makes me sick. Thanks for your patience and knowledge.
Glad to help. Why don't you try e.g. canned salmon? Pink salmon is cheap ($0.99 Cdn., on sale), and will supply other good stuff too. Sardines, herring, are other alternatives which are high in fat, and low in pollutant burden.
Posted by kara lynne on November 25, 2002, at 14:06:14
In reply to Re: What about evening primrose or borage oil?, posted by Larry Hoover on November 25, 2002, at 13:37:19
Maybe I will try canned salmon, although I'm always a bit dubious about eating anything from a can. The thought of sardines and herring makes me shudder (!), but of course I love tuna which is supposed to have too much mercury. I try to eat cooked salmon whenever possible, but lately have been scared away by news stories about that as well. It's getting to be that you can't eat anything without impunity; just like that old Joe Jackson song, "Everything Gives You Cancer". So sometimes I just give up and eat chocolate and drink Coke (from a bottle, of course). Thanks again.
Posted by kara lynne on November 25, 2002, at 14:13:56
In reply to Re: What about evening primrose or borage oil?, posted by kara lynne on November 25, 2002, at 14:06:14
...can't eat anything *with* impunity.
Posted by viridis on November 26, 2002, at 5:02:16
In reply to Re: What about evening primrose or borage oil?, posted by Larry Hoover on November 25, 2002, at 13:37:19
Hi Larry,
Since we're picking your brains on lipid metabolism (and you seem very knowledgeable), could you offer a brief synopsis/opinion on hempseed oil (and pumpkinseed oil too, if possible)?
Thanks in advance,
Viridis
Posted by Larry Hoover on November 26, 2002, at 9:08:41
In reply to Hempseed oil? » Larry Hoover, posted by viridis on November 26, 2002, at 5:02:16
> Hi Larry,
>
> Since we're picking your brains on lipid metabolism (and you seem very knowledgeable), could you offer a brief synopsis/opinion on hempseed oil (and pumpkinseed oil too, if possible)?
>
> Thanks in advance,
>
> ViridisSure.
Hemp oil has a good fatty acid balance, I suppose, but only in comparison with other vegetable oils. It might be rather unique in being a source for both isomers of 18:3 linolenic acid. Still, it falls short of the target of 1:1 ratio of omega-6:omega-3. I've heard it said that hemp is also a source of EPA, but that is not correct; the 20 carbon fatty acid is a mono-ene, and is not interconvertable with EPA. It's in low concentration, in any case.
hemp oil:
gamma-Linolenic acid (18:3 omega-6) 3.10%
alpha-Linolenic acid (18:3 omega-3) 20.00%
Eicosaenoic acid (20:1) 0.50%Data on pumpkinseed oil is harder to find. It's main claim to fame, I suppose, is its high linoleic acid content (50-60%). Linoleic acid is an 18:2 omega-6 (please note the confusing similarity of the name with linolenic acid, which is 18:3). Linoleic acid has the dubious merit of being considered to be an essential fatty acid. It was merely the first to be identified, and some still say the only such fatty acid. Despite the burgeoning evidence of the essentiality of omega-3 fatty acids, some still cling to this old concept. With the huge amount of vegetable oils being consumed today, there is a virtual zero per cent likelihood that anyone needs more 18:2 linoleic than they're already getting. There's very little of the higher polyunsaturates to consider, so I don't see anything in any way special about pumpkinseed oil. Pumpkin seeds, however, are a different matter. They're quite nutritious.
pumpkinseed oil:
total PUFAs (not linoleic): <2%The take-home message is that I don't see anything particularly special about these oils, but hemp has a better profile. Cold-pressed oils may contain other fat-soluble materials like phytoestrogens (e.g. beta-sitosterol), but that's another story.
Lar
Posted by viridis on November 27, 2002, at 0:29:36
In reply to Re: Hempseed oil?, posted by Larry Hoover on November 26, 2002, at 9:08:41
Hi Larry,
Many thanks for the insights. A lot of these oils get hyped for their health benefits, and I just don't have the time (or knowledge of biochemistry) to investigate each the way you have. I do like hempseed oil (it has a nice flavor in salad dressings), but some of the claims for its health benefits sound a bit...fishy?
I was curious about pumpkinseed oil because it's become a trendy restaurant item, and there are a few websites that tout it as the latest miracle cure.
I use a variety of oils (mostly olive and some canola for cooking, and cold-pressed olive, nut, flax, and hempseed for various non-heated condiments like salad dressings), but also take a few grams of fish oil each day, in addition to eating quite a bit of fish. It sounds like fish oil is really the way to go for direct assimilation of omega 3s.
OK, one more for you -- purslane (popular as a salad vegetable in Europe, mostly an ornamental or weed here) is supposed to be high in omega-3 fatty acids. Any truth to this claim, or are these again just precursors?
Posted by Larry Hoover on November 27, 2002, at 9:06:32
In reply to Re: Hempseed oil?, posted by viridis on November 27, 2002, at 0:29:36
> Hi Larry,
>
> Many thanks for the insights. A lot of these oils get hyped for their health benefits, and I just don't have the time (or knowledge of biochemistry) to investigate each the way you have. I do like hempseed oil (it has a nice flavor in salad dressings), but some of the claims for its health benefits sound a bit...fishy?Hype is exactly the problem, as in hyperbole. If health quacks just gave the facts, people can make up their own minds.
> I was curious about pumpkinseed oil because it's become a trendy restaurant item, and there are a few websites that tout it as the latest miracle cure.
Not having used it, I can't make a comment on that, but I presume it has an interesting flavour. A few drops of sesame oil, for example, can totally transform a dish.
> I use a variety of oils (mostly olive and some canola for cooking, and cold-pressed olive, nut, flax, and hempseed for various non-heated condiments like salad dressings), but also take a few grams of fish oil each day, in addition to eating quite a bit of fish. It sounds like fish oil is really the way to go for direct assimilation of omega 3s.
There is nothing else to compare to it. Using a variety of oils is a good thing, but I'd avoid canola for frying. The high PUFA content makes it liable to break down under heat. Sunflower oil is an option for frying. I should check smoking temperatures and get back to you.
> OK, one more for you -- purslane (popular as a salad vegetable in Europe, mostly an ornamental or weed here) is supposed to be high in omega-3 fatty acids. Any truth to this claim, or are these again just precursors?Purslane is unique among herbs in being a good source of omega-3s. Most of that is alpha-linolenic (18:3), but there are small amounts of EPA and DHA. Trace amounts, but that suggests to me that some genetic races of this herb can contain more. I didn't see any mention of omega-6 fats. One of the factors that some have suggested as contributing to the low levels of heart disease in Mediterranean populations is the use of purslane as a potherb. BTW, portulaca, or moss rose, the garden flower, is edible. I'm not sure if it's the same species, but it's the same genus. There's also a common garden weed that's a portulaca, but I can't think of the name of it.
Lar
Posted by IsoM on November 27, 2002, at 12:53:25
In reply to Re: Hempseed oil?, posted by Larry Hoover on November 27, 2002, at 9:06:32
Viridis, purslane is the same as the garden weed some people called wild portulaca - it's Portulaca oleracea. I've eaten it lots & like the taste & while it's supposed to be rich in omega-3, think for a minute of where it would be - the seeds.
It's one of the complaints I have against blanket analysis of beneficial plants. Often, what part of the plant is rich in certain nutrients isn't specified so people assume the whole plant is a good source. Only once, did I read that --
"purslane has the highest omega-3 profile of all plants in what small amount of fats is found in purslane"
-- so I think you get an idea of how much is in it. It’s true that chickens that have eaten lots of purslane have higher omega-3 in their eggs, but chickens can eat a lot of purslane & the omega-3 fats are concentrated in the eggs for the developing chicks.Even if little omega-3 is found in purslane, it wouldn't stop me from eating it, I like the taste. But it does have a fair amount of oxalic acid, which can interfere with calcium absorption. It's supposed to have 1.31 g oxalic acid per 100 g purslane - quite high; but then, so does parsley, & it doesn't stop me from eating hummus with lots of parsley.
Here's what I found on purslane:
http://www.nal.usda.gov/fnic/cgi-bin/list_nut.pl
You can find a lot from the USDA Nutrient Data Lab http://www.nal.usda.gov/fnic/cgi-bin/nut_search.pl
one of the main complaints I have about the Canadian equivalent - very few reference sources for the average person, but the American site is good.--Will write you back soon. I've been very busy too as I'm sure you understand.-- ^_^
Posted by Larry Hoover on November 27, 2002, at 13:04:43
In reply to Re: Purslane, posted by IsoM on November 27, 2002, at 12:53:25
> Viridis, purslane is the same as the garden weed some people called wild portulaca - it's Portulaca oleracea. I've eaten it lots & like the taste & while it's supposed to be rich in omega-3, think for a minute of where it would be - the seeds.
Do the search here, and it says the omega-3s are in the herb:
<shrug>
Posted by IsoM on November 27, 2002, at 13:54:33
In reply to Re: Purslane, posted by Larry Hoover on November 27, 2002, at 13:04:43
Ah, Larry, I love you. I lost Jim Duke's site, wasn't sure of his name at the time, & when we transferred info to our new computer, I lost it. I thought I'd bookmarked his site. I'll email him & ask more about purslane & let virids know what he says. I trust Duke's science & integrity.
I'd heard of him a few years ago & his interest in botany relating to phytonutrients. I'm so glad you linked to his site & I now have it again. Thank you, thank you!!
Posted by Larry Hoover on November 27, 2002, at 14:29:46
In reply to Re: Purslane » Larry Hoover, posted by IsoM on November 27, 2002, at 13:54:33
> Ah, Larry, I love you.
<blush>
>I lost Jim Duke's site, wasn't sure of his name at the time, & when we transferred info to our new computer, I lost it.
My biggest criticism is I don't know how he references things.
Lar
Posted by IsoM on November 27, 2002, at 17:21:03
In reply to Re: Purslane, posted by Larry Hoover on November 27, 2002, at 14:29:46
Let's ask him then! If I hear back from him, I'll ask him what he uses as a reference. I read years ago that he was intensely interested in the therapeutical effects of plants & had previously been a herbalist or something similar. But he wanted to learn more about the science behind it & went back to get a doctorate. So he has a natural bias in favour of plants. That's not necessarily a bad thing as I do too, but if one isn't completely objective about so-called benefits, more can be credited to plants than is true, or at least known now.
Posted by viridis on November 28, 2002, at 0:52:18
In reply to Re: Purslane, posted by IsoM on November 27, 2002, at 12:53:25
Hi Larry and IsoM,
Thanks for the info Larry, and confirmation that purslane (and Portulaca) do contain omega-3s. That is a good point, IsoM -- you'd think the oils would be in the seeds (and purslane seed is tiny, almost dust-like; I can't imagine grinding it up). It's interesting that the oils may actually be in the plant itself.
I like purslane. Here in the southern US, we have the wild form in our yard, and also grow tons of the ornamental cultivars in the summer. It's extremely heat- and drought-tolerant (essentially a succulent), spreads fast, and even the tiniest piece will root. I sometimes toss wild and cultivated purslane in salads, but mostly we use it as a garden flower. I may start eating it more!
P.S. IsoM: I look forward to hearing from you -- things are pretty hectic for me too, but I'm hoping they'll settle down in a couple of weeks.
This is the end of the thread.
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