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marylin monroe
Showing posts with label vegetable oils. Show all posts
Showing posts with label vegetable oils. Show all posts

Some Things Fishy: Oxidized Fish Oil Totally Benign!?Plus: The Inflammatory Side of EPA and Peroxide & Alkenal Levels in Commercial Fish and Vegetable Oils.

Image 1: Surströmming, a Swedish delicates is essentially rancid fish and it stinks exactly like that. Now, the results of a recent study show that the rancidity does probably not compromise the health benefits of the fish... so if you like it, go for it!
You know that whenever something is so (over-)hyped like fish oil or vitamin D that rings an alarm with me and when I hear "experts" on popular podcast say things along the lines of "as long as you take your fish oil that can compensate for a whacky diet", this is totally burning me up. Yes, there is conclusive evidence that for someone who has damaged his/her body by years and years of omega-6 over-consumption the inclusion of even "high" dose (I consider 5-6g high!) fish oil supplements can make sense, but NO, it will neither allow you to keep eating the same crap that has brought you to where you are at now, nor (and I think this is even more important for most of the SuppVersity readers) is there conclusive evidence that a healthy, active and lean human being is not way better off by limiting his total PUFA intake instead of popping grams of highly oxidizable n-3 fatty acids from fish oil caps.

Highly oxidizable? Yes! Dangerous? Surprisingly not!

A pros pos "highly oxidizable", the argument that polyunsaturated fatty acids (PUFAs) are readily oxidized not only in your body, but even at the shelves of your nutrition store, is one of the few possible caveats of fish oils supplementation even fish oil enthusiasts will acknowledge. After all previous animal studies have shown that diets rich (5%) in rancid (=oxidized) fish oils lead to increases in thiobarbituric acid-reactive substances (TBARS) levels and elevate liver specific transaminases, as well as the alkaline phosphatase (ALP) levels in the plasma of rats (detrimental effects which can by the way be ameliorated by taurine supplementation, cf. Hwang. 2000). The results of a recent study by Inger Ottestad and colleagues from Norway may thusly surprise the "pro-fish oil"-faction about as much as they surprised me (Ottestad. 2011): The ingestion of 8g of oxidized (peroxide value: 18mEq/kg; ansidine value: 9) fish oil (1.6g EPA+DHA) did not have any unfavorable short term-effects in previously healthy individuals.
Figure 1: Serum (left, 8-iso on secondary axes was measured in urine) and erythrocyte (right, GPx on secondary axes) markers of oxidative stress in 68 healthy subjects who were randomly assigned to ingest 8g of "fresh" fish oil, oxidized fish oil or high oleic-acid sunflower oil per day for before (pre) and after (post) the 7 week intervention (data adapted from Ottestad. 2011)
If you take a closer look at the measured levels of serum (4-hydroxy-2-hexenal: 4-HHE, 4-hydroxy-2-nonenal: 4-HNE, alpha-tocopherol,  high-sensitive C-reactive protein: hsCRP and 8-iso-PFG2a, the latter in urine) as well as erythrocyte (total GSH, 4-hydroxy-2-nonena: GR, CAT and glutathione peroxidase: GPx) markers of oxidation before and after the 7-week intervention (cf. figure 1), it is quite obvious that there were no statistically significant oxidation-related changes in the concentrations of the measured markers of oxidative stress, of which the scientists state that they are the current, yet debatable, "gold standard" for in vivo studies.
Figure 2: Changes in n-3 and n-6 levels and the n-6/n-3 ratio (small graph) in the course of the study period (data calculated based on Ottestad. 2011)
It is thus not really surprising that both fish oil groups experienced virtually identical (and highly favorable) -50% reductions in the ratio of omega-6 (n-6) to omega-3 (n-3) fatty acids. Moreover, ...
[a]fter 3 and 7 weeks of intervention, the plasma level of EPA, docosapentaenoic acid and DHA were significantly increased in both fish oil groups compared to the HOSO group, but no significant difference in EPA, doc-osapentaenoic acid and DHA between the FO and oxFO groups was observed.
The scientists are thusly right to conclude that their results do not support the often-heard hypothesis that higher intakes n-3 long-chain fatty acids could increase in vivo lipid peroxidation and more importantly, that ...
[...] the content of hydroperoxides in fish oil supplements, even with a PV that exceeds the European Pharmacopeia for marine n-3 oils, does not apparently influence the plasma level of n-3 FA.
With regards to the obvious differences to previous animal studies, the scientists state that secondary oxidation of hydroperoxides, which are then absorbed in the intestine has until now been observed in animal and cell studies. In view of the relative short duration of the study and the reliance on healthy subjects, it is also questionable whether identical results would have been achieved, when sick patients (the usual customer group at least for the pharma-grade n-3 supplements) had been treated with the same product for years.

Oxidized fats in fish oil and beyond

It is also worth mentioning that Ottestad et al. are not sure, whether their "aritifically oxidized" fish oil (oxidation was achieved by sparkling pure oxygen through the oil for 20 min twice a day for 21 d) was an appropriate model for commercially available (oxidized) fish oils. After all, there could be major differences in the composition of the oxidation products, when the oils go rancid over months or get damaged by heat etc. While I obviously cannot answer this question without setting up my own lab, I can however tell you that another recent study by Halvorsen et al. who examined the peroxide and alkenal (one of the major products of secondary oxidation) content of fish and vegetable oils, found average peroxide levels in 33 commercially available fish oil products (mean PV: 3.61mEq/kg) that were ~500% below the ones of the oxidized fish oil (18mEq/kg) in the Ottestad study.
Figure 3: Mean peroxide and alkenal values of 33 commercially available fish and 35 vegetable oils (Halvorsen. 2011).
In this regards, fresh vegetable oils, obviously are way in front, as the data from a study by Bente Lise Halvorsen and Rune Blomhoff clearly shows, that they have lower peroxide and much lower alkenal levels than fish oils (cf. figure 3). Interestingly, vegetable oils are also less prone to being oxidized during storage, something Halvorsen and Blomhoff conclude based on the absence of the "negative correlation (r=−0.557, p<0.001) [...] between the number of days until expiry and the PV [peroxide value]" they observed in the marine omega-3 oils.
Figure 4: Peroxide (PV in mEq/kg) and alkenal (in nM/ml) levels in fresh vegetable oils and after being heated for 25 minutes at 225°C in an oven (data adapted from Halvorsen. 2011); solid red line - maximal peroxide value for olive oils, dotted red line - maximal peroxide values for fish oils as suggested by Turner et al. (Turner. 2006)
Contrary to fish oils, which are usually taken "fresh" and in a capped form, the main fate of vegetable is however to be (ab-)used as cooking / frying oils. During the heating process, the amount of secondary lipid oxidation products, the alkenals, doubles or quadruples depending on the type of oil (cf. figure 4). In that, it may at first seem counterintuitive that, when the scientists heated the samples for 25 minutes at 225°C in an oven, the amount of primary oxidation products was slightly reduced in most, but not all (e.g. soy bean oil) of the 11 vegetable oils. If you do yet take into consideration that the latter are the "raw material" for the secondary oxidation products, it becomes quite clear that this is not a desirable process ;-)
Image 3: Extra virgin olive oils (EVOOs) have generally higher peroxide values than the cheap refined stuff, and yet, EVOOs and not refined oils have been shown to exhibit numerous health benefits.
Putting peroxide values (PV) into perspective: All potential health hazards aside, it may be interesting to know that the general "rule of thumb" says that a fat is rancid when the PV is about 10 meq/kg (the fish oil in the study with PV=18 was thusly "rancid"). A fresh and refined product on the other hand should have PV below 1 meq/kg (Gunstone. 1996). That being said, it may surprise you that for high quality extra virgin olive oils, the PV limit is 20meq/kg, while for "regular" olive oil it is only 10 meq/kg. If you know look at studies related to the health benefits of refined vs. extra virgin olive oil, you will have to admit that - quite obviously - fish oil apparently is not the only oil, where increased peroxide levels do not negate the beneficial health effects of the oil.
So, if pure vegetable oils are generally "fresher" than fish oils does that mean that as long as you do not heat them, they are the better choice? No, they are not! I mean, look at the research that is out there... the abundance of n-6 fatty acids in the "healthy" vegetable oils that are getting pimped especially by the US government, is at the heart of an epidemic of which the authorities still claim that it was caused by high cholesterol levels. Instead banning all saturated fats from YourPlate (which should never look like the governments MyPlate ;-), you should rather incorporate more coconut oil and saturated fats from butter, beef etc. into your diet. Select (vegetable) oils that are relatively high in mono-unsaturated fatty acids, like extra virgin olive oil (don't care about its high peroxide value, cf. red box above) and try to reduce the amount of n-6 fats you ingest - you will get more than enough even from grass-fed meats, olive and other oils and any processed foods that may still be part of your diet, anyway.
Image 4: Not all Omega-3 are created equal. We know for some time that DHA (not EPA) is what your brain needs and a recent study from Norway suggest that eicosapentaenoic acid (EPA) is actually pro- not anti-inflammatory at a cellular level. It may yet well be that this in turn triggers a beneficial hormetic response which would support my "fish oil = exercise in a pill hypothesis"
Although this is not directly related to the topic of oxidation I still want to add that another study appears to confirms my long-cherished skepticism towards EPA (most fish oils have a 2:1 EPA to DHA ratio), which, as a recent study from Norwegian scientists shows (Myhrstad. 2011), is not really "beneficial super-antioxidant" people are led to believe. In their trial the scientists fed 14 healthy female volunteers test meals. The cakes the participants ate were enriched with either flaxseed, cod liver or coconut oil and the intention of the study was to elucidate differential effects of meal fatty acid composition on inflammatory markers. Not to my, but probably to the scientists surprise the "evil" saturated fat from the coconut oil turned out to be similarly benign as the flaxseed cake. Only the EPA-laden cod liver oil cake produced a statistically significant increase in IL-8 mRNA levels 6h post ingestion. Similarly, incubation of peripheral blood mononuclear cells with EPA, yet not ALA lead to >3x increase in IL-8 and >2x increases in IL-6 mRNA expression.

While I am not quite sure what to make of these observations, these results stand in line with previous studies reporting differential effects of EPA vs. DHA rich fish-oils, where across the board, the DHA appeared to be the major driving force of the beneficial health effects people hope to be getting from their fish oil caps (e.g. brain health, Engström. 2009).
Fish oil caps can be a good addition to this regimen specifically for those who are just about to start out on a low omega-6 diet to offset the skewed n-6 to n-3 ratio (something that takes its time). They are yet by no means obligatory for someone who eats fish on a regular basis and invests the extra bucks into grass-fed beef and eggs from pastured chicken. If you thusly satisfy your (anyway low) dietary DHA requirements... and most importantly, taking fish oil will not compensate for eating shitloads of processed foods and lack of exercise, even if the aforementioned pro-inflammatory effects of EPA support my previously uttered hypothesis that fish oil has some resemblance to "exercise in a pill".

Conventional vs. Organic: It's Not About Getting More, But Getting Less For Your Money. Less Pesticides, Dioxins & Co

Image 1: The Ökomonitoring program took a very different approach to the question whether or not organic products are worth the extra cost, they did not look for the additional edge, but rather the "subtractive edge", if you will, and tried to answer the question: "Can we even produce 'organically' in an increasingly polluted environment"; now ten years after the program started the answer appears to be "Yes!" (MLR. 2012a)
"Organic produce is no better than conventional! You are being ripped off!" Statements like this have made the headlines in the past couple of days and many people (obviously not you, though!) are scandalized or shaking their head haughtily uttering things "I knew it, and that's why I always buy the cheapest..." What both groups are missing, though is the simple fact that the question the scientists posed, or rather the question the journalists put to the forefront, i.e. "Are organically produced fruits and vegetables more nutritious?", is nonsensical, because it would imply that the absence of certain chemical agents and production methods would increase the amount of nutrients a plant puts into its fruit, leaves, roots or whatever. Since I have discussed this with my friend Carl Lanore on yesterday's joint SHR + SuppVersity News Round Up pretty extensively (in fact so extensive that we could not cover the other topics I had lined up - sorry for that, folks!), I won't go into more detail on that here, but simply repeat that the fallacy of this approach was part of my reasoning not to bore you with write-up / comment #5325 published that's been published on the bazillion of blogs within the past couple of days, but rather give you the long and short of a governmentally subsidized program that's been running for 10 years, now, here in Germany: the Ökomonitorin program of in Baden-Württemberg (this is one of the individual states here in Germany).

It's not about what's in there, but about what is not!

The researchers who are mainly working at the University of Stuttgart set out with a whole different research question than most of their colleagues. Rather than trying to answer loosely defined questions such as "What's better: Conventional or organic", they wanted to know whether or not it would even be possible to "produce organic" in an environment that is already profoundly polluted; and though I don't want to give away too much in advance, after 10 years and ten-thousands of samples of organic and conventional fruits, vegetables and animal products being analyzed the answer is "Yes it is!"
"Organic fruits and vegetables had on average 180x lower pesticide content than conventional products; and only 5% of the samples from organic produce were objectionable."
That's the conclusion the researchers in the 10-years special report that has been published in July 2012 (MLR. 2012b). Since I know that you don't content yourself with universalities like this (otherwise you would hardly be here ;-), I would like to invite you to let me walk you through some of the detailed results of the latest data from 2011, although this may not be the exact same goods you have (or haven't) been buying in the course of the last year (I just checked: Only ~6% of you are actually from Germany)

The good the bad and the equally ugly

While the general trend that emerges does in fact speak in favor of the organic products, a brief look at the data in figure 1 should suffice to see that despite the fact that the number of offenders, i.e. products with pesticide residues above the maximally allowed threshold is close to zero, even organic produce is far from being pesticide free.
Figure 1: Percentage of conventionally and organically produced products with detectable (those did not have to be above the allowed threshold levels!) pesticide residues (data based on MLR. 2012a)
Of all the categories I picked when I compiled figure 1 there are however four product categories that caught my eye immediately, because the "organic advantage" as you may call it, is particularly small, here: Wine, plant oils and processed fruit and vegetables (the latter category included frozen, usually relatively pesticide free, but also canned food and dried foods, as well as fruit jars etc.). Intriguingly, in all of those four the pesticides could (and in the case of the Wine, the researchers even proved that) have gotten into the food-chain during the processing / manufacturing process, as well - in other words processed and organic tend to be contrastive pairs.
Figure 2: Percentage of products with pesticide levels above the allowed threshold (data based on MLR. 2012a)
When it comes to the actual "offenders", i.e. those products with levels above what is officially allowed, here in Europe, there are actually seven of which I feel that they really stand out (one for each day of the week, isn't that great?):
Mothercorn, the "abortion fungus" of the middle ages, the first source of LSD and the result of inappropriately stored and subsequently moldy grains / flour being used in the production of breads, is a potential cause of auto-immune diseases and lethal toxicities.
The mothercorn (Claviceps purpurea) content [µg/kg] of multi-grain breads with rye and wholemeal rye bread (please mind the leap on the primary axis; data based on MLE. 2012a)
The ingestion of 2 mg of mothercorn does already lead to adverse reactions which range from nausea over headaches, and cramping to a loss of sensation in the extremities and vascular occlusions (the latter will also arise from chronic low-grade intoxications)- in pregnant women it will induce contractions of the uterus and spontaneous abortion. The ingestion of 5-10g of the ergot-alkaloids from the fungus kill an adult man... not exactly what you want to have in your bread, right? Not even in "harmless quantities" - which is what even the worst offenders would have to be considered, still.
  • the processed foods - irrespective of whether you buy veggies or fruit, you can be sure that the contamination raises with every processing step; be smart not lazy and buy whole foods, learn how to prepare them and cook for yourself
  • cereals - 3.4% of the "oh so healthy superfoods", of which at total 72% of the conventional and 36% of the organic ones contain pesticides, are also on the list of items even the European officials suggest you should better not eat, if you don't want to become sick
  • legumes - another favorite of mainstream dietitians are not just among the worst offenders (24% of the conventionally produced legumes contain pesticides above the tolerable limit), they are also the only product where even the organic variety is not suitable for human consumption in 11% of the cases and as if that was not enough, the number of substances above that threshold amounts to 17 compounds in the conventional and 3 substances in the organically produced legumes
  • leafy greens - the health food per se may not be among the worst offenders but in those 6.7% of the samples that had pesticides above the the threshold level, the scientist were able to identify 27(!) different pesticides (note: not all pesticides were found in all samples and the worst offenders were not broccoli & co, but rather salads)
  • ginger (=ingwer)- the conventional variety something many people use to improve their health had higher than tolerable levels in 12.5% of the cases; a health food "gone unhealthy", if you will
  • berries - they may not be among the worst offenders, but they are "versatile": With 5 different pesticides in the samples the scientists analyzed they can't compare with the processed veggies with 45 different pesticides, but are doing quite "well"
  • exotic fruit and citrus fruit - while with them the conventional farmers obviously assume that the consumer would throw away the peel anyway; or, and this segues right into our next topic, there are no governmental controls and regulations in place; after all, you should be aware that Germany is not exactly the country to grow "exotic fruits" ;-)
If we seize on the notion of "it's not us, it's only the others that contaminate their produce, ship it to Europe (or the US) and poison us", we must however realize that things aren't so easy as they seem: While the German organic produce may in fact be the less polluted one, neither the Israelis nor the South Africans or Moroccans, but rather our European friends, the Italians are trying to poison us ;-)
Figure Y: "Worst offenders" statistics for the countries of origin of organic produce (based on MLR. 2012b)
Now, all jokes aside, it is simply not possible and probably also highly un-rewarding to replace one prejudice, i.e. all organic produce is good with another more sophisticated one such as all organic produce from Germany is good and everything from Italy, Egypt and Greece is poison. Therefore, it is probably also not so important that the intricacies of these statistics are meaningless for the majority of you who are (I just checked) US residents and not among the 6% "resident" (=German) SuppVersity students ;-)

Organic = Say no to GMO!?

With the different legislative situation here in Germany, the quantitative data on GMO "contamination" in figure 3 is probably likewise irrelevant for many of you, but with the production of GMO corn being banned, here in Germany, it does give you a sneak peak on what can happen if the government is willing to act on behalf of its people (the majority of Germans is against GMO) instead of the industry (in all fairness it must be said that it is the US and not the European, let alone the German agrar-industry that's constantly trying to push GMO corn and other produce into the German market).
Figure 4: Relative percantage of soy and soyproducts that has been genetically modified (MLR. 2012b)
Even among the conventional produce, the number of outliers was small - roughly 5% of conventional products contained <0.1% corn from genetically modified plants - a result which is probably also to be accounted for by the awareness of the industry that they will have to throw all their produce away once the GMO-skeptic consumers realize that product is contains significant amounts of genetically modified plants.

The data in figure 4 does yet also show that things look different for soy products, most of which are imported from countries where the production of GMO foods is actually allowed (like the US ;-) and even non-GMO crop can be exposed to cross-contamination. If we take a closer look and discard the annual variations, it does yet become obvious that the GMO content of organic products is just as their pesticide content still much lower than it is in conventional ones. What is pretty troublesome, though, is that in 2011 25% of the products that are advertised as "GMO free" contained small amounts (<0.1%) of genetically modified soy - for you, my American friends this means: Having a label alone does not protect you from "GMO fraud" ;-)

Eggs, salmon, animal productts and other notable observations and changes from 2002-2012

Before I'll conclude this post with a couple of notes on trends and general observations the scientists who have been working on the Ökomonitoring program over the past 10 years made and let you make up your own mind of "whether or not you feel that getting less is worth paying more", let me briefly address the issue of dioxin-laden organic eggs Carl and I have been talking about, yesterday, already:

Image 2: If you have not done so, already, I highly suggest you read my previous post "Urban Gardening: 12x More Cadmium in Your Tomatoes Than in the Conventional Produce? Plus: Domestic vs. Foreign - What's Healthier?". After all, your own organic tomatoes and other produce can be effected by the environment in which you grow them, as well.
  • Not just organically produced eggs, but also organically produced salmon have on average higher levels of DDT, PCB and total dioxins (TEQ) and HCB, DDT2, PCB 153, Dieldrin, Endosulfan, Chlordan, Toxaphen, Tribromanisol, PBDE, respectively (note: wild salmon is almost free of any of the latter!)
  • Those contaminations are not brought about by what the farmers do, but rather what they didn't do, i.e. make sure that their free ranging hens are not running around on toxic soils and their fish are not swimming in a toxic sea - and this is where the initial research question of the Ökomonitoring program, "Can we even produce organically?", must be answered with a somewhat shabby: "It depends" and the one parameter it depends on is the environment, to which the animals (and to a much lesser degree, the crop) are exposed
Now, the implications of this are not that all organic animal products are worse than their conventional counterparts (in fact the number of products without any residues is larger for the organic products, unfortunately those products which are contaminated contain much higher levels!), but rather that you have to be choosier and try not to rely on the label "organic", if you know your local farmer and trust him, you may be better off buying his non-organic eggs that those from an organic farm on contaminated land...
Find out if your area has contaminated soil by using the MyEnvironment search engine at epa.gov! Enter your area code and get the result right away. If you type in "Bronx New York", for example, you will learn that the major risk factor from air pollution is formaldehyde, that there are two final NPL sites and so on and so forth (thanks to Carl Lanore and Alisa Profumo for pointing this out on today's Casual Friday).
But enough of that let's wrap it up for today, with a couple of more or less unrelated, but interesting facts, the first of which is so important that I decided to repeat it, although I mentioned it at the beginning of the article, already:
What is Furan? Furan is a heterocyclic compound that has originally been used in the chemical manufacturing industry. It does however also occur during the combustion of coal and is a component of tobacco smoke, as well as in a number of heat processed food items such as canned and jarred foods and coffee (FDA. 2004). Furan is carcinogenic to rats and mice and was classified as ‘possibly carcinogenic to humans’ (International Agency for Research on Cancer, 1995; see as well Cordelli. 2010; Chen. 2012)
  • on average 180x lower pesticide residues in organic fruits and veggies - that's the astonishing result after 10 years of Ökomonitoring
  • no = ZERO pharamcologically active substances in any of the testes organic produces
  • antibiotics residues in organic honey were reduced from 23% to 0% from 2003 to 2005; no complaints thereafter
  • the mycotoxin load is about equally high in conventional and organic produce
  • No significant differences in terms of organic contamination and pesticide residues exist between animal products; the dioxin load in eggs free ranging hens and organic salmon are exceptions to this rule (while levels spiked in 2009, when "buying organic" really took off over here and more and more farmers started producing "organic eggs", the levels have been slightly declining over the past years)
  • the way organic coffee is roasted leads to increased furan levels in organically produced roast coffee
  • the amount of acrylamide in cookies is equally high in organic vs. conventional products, the in organic chips is higher and the number of samples with levels above the 1,000µg/kg threshold is higher as well
  • no differences were found in terms of trans fatty acids in ready-made meals
  • organic softdrinks are free of preservatives
  • no artificial colorings in organic sweets
Now it's up to you - organic, yes or no? And remember: We cannot always make everything 100% right, but that does not mean that you should give up trying.


References:
  • Chen T, Williams TD, Mally A, Hamberger C, Mirbahai L, Hickling K, Chipman JK. Gene expression and epigenetic changes by furan in rat liver. Toxicology. 2012 Feb 26;292(2-3):63-70.
  • Cordelli E, Leopardi P, Villani P, Marcon F, Macrì C, Caiola S, Siniscalchi E, Conti L, Eleuteri P, Malchiodi-Albedi F, Crebelli R. Toxic and genotoxic effects of oral administration of furan in mouse liver. Mutagenesis. 2010 May;25(3):305-14.
  • Food and Drug Administration. Exploratory Data on Furan in Food, vol. 2011. 2004 < http://www.cfsan.fda.gov/∼dms/furandat.html >
  • International Agency for Research on Cancer. Summaries & Evaluations, vol. 2011. 1995. 
  • Ministerium für Ländlichen Raum, und Verbraucherschutz Baden-Württemberg (MLR). Ökomonitoring. Ökomonitoring Bericht für das Jahr 2011. June 2012b.
  • Ministerium für Ländlichen Raum, und Verbraucherschutz Baden-Württemberg (MLR).Ökomonitoring. 10 Jahre Ökomonitoring. 2002 – 2011. Jubiläumssonderausgabe. June 2012b.

Obese Vegan Salmon!? Vegetable Oils and Proteins Reduce DHA and EPA Content by -28% and Increase Overall Adiposity and Triglyceride Levels in Atlantic Salmon.

Image 1: Could this be made of obes vegan
salmon? (img from littlesteps.eu)
If you listened to yesterday's episode of Carl Lenore's Super Human Radio, you may remember that I repeatedly pointed out that "not all milk is created equal" and that milk quality is determined by food quality (if you want to read more about milk in general and colostrum in particular, I suggest you read last week's Ask Dr. Andro, as well). Today I am going to tell you about another of the industry's economic (in the monetary sense) ways of reducing the quality of animal foods in our foodchain - and we are talking about a food with a much better reputation than milk or beef: Salmon, the "heart-healthy cold-water fish" that is literally in on (or rather between) everyone's lips, lately.
Note: Salmon is explicitly mentioned in the "sample one-day menu" scientists at Colorado State developed according to the USDA dietary guidelines (Dietary Guidelines for Americans), so don't tell me you are not supposed to eat Norwegian fish, anyway, because you, my American friends, are supposed to have Grilled salmon, steamed broccoli, barley pilaf, low-fat milk and cake with fresh berries for dinner ;-)
Bente E. Torstensen and his (her?) collegues from the National Institute of Nutrition and Seafood Research and the Skretting Aquaculture Research Centre in Norway conducted an interesting experiment (Torstensen. 2011). For about a year, the researchers fed 6,000 smolt of Atlantic salmon (mean weight 355g) which had previously been randomly assigned to one out of three experimental + one control groups with diets containing...
  • maximal amounts of fish meal and fish oil (Control)
  • the "safe maximum replacement" of both fish meal and fish oil with plant meal (80% plant protein) and vegetable oil (70% vegetable oil) (80PP70VO)
  • half the maximum replacement with plant meal (40%) and maximal replacement with vegetable oil (70%) (40PP70VO)
  • maximum replacement with plant protein (80%) and half of the maximal replacement with vegetable oil (35%) (80PP35VO)
While the control diet obviously resembles what salmon, which primarily feeds on other fish, would naturally eat, the diet composition of group 2 remotely reminds me of what the food-industry has been feeding the less health-conscious masses in the US and Europe over the last decades. What... as a animal-loving vegan you are more interested in the fate of the poor salmon than in that of your sick and obese fellow human beings? Ok, here is what happened:
Maximum dietary VO [vegetable oil] and PP [plant protein replacements] increased visceral lipid stores, liver TAG, and plasma VLDL and TAG concentrations. Increased plasma TAG correlated with an increased expression of apoB100, indicating increased VLDL assembly in the liver of fish fed the high-plant protein- and VO-based diet.
Veganism, it turns out, ain't the preferable diet for salmon. Depending on which end of the dietary spectrum you belong to - the carnivorous hunter or the vegan gatherer -  you will probably now be asking yourselves one of the following questions:
  1. Hunter: "What does that have to do with me? I always knew plant proteins and oils are bad for you!"
  2. Gatherer: "What does that have to do with me? I don't eat salmon and the results from a 'fish-model' certainly won't apply to human beings!"
In isolation both the carnivorous hunter as well as the vegan gatherer appear right, when they ignore a prick like me citing the results of an insignificant fish study, the amalgam of both of these trains of thought does yet bring up a more unsettling question: What happens to the average health-conscious customer on a budget who thinks he is doing him/herself good by frying his economically raised, i.e. vegetable oil and protein fed, salmon in "healthy" vegetable oils and finishes dinner with a tofu dish? To be honest, I don't think we really need a study to answer that question. You just have to look at your peers to see the health consequences of eating sick animals and other vegetables that were either never intended for human consumption or have been (over-)processed beyond all recognition.
Figure 1: Relative changes in the fatty acid profile compared to "real", i.e. fish-fed, salmon after 1 year on vegetable oil and protein (data calculated based on Torstensen. 2011)
A pros pos "beyond recognition" if you have a closer look at the combined effects of vegetable oils and proteins on the fatty acid (figure 1) of the fish you will notice that industrially produced salmon fed with the "safe maximum replacement" dose of vegetable oils and proteins has little resemblance with the healthy food most consumers believe they were eating, when they buy "salmon" at the grocery store. Most obviously, the beneficial n3:n6 ratio of 7.6 in "real" salmon changed for the worse and ended up at roughly 3.0 after one year on a 80% plant protein 70% vegetable oil diet. Moreover, the individual composition of the fatty acids changed, as well. These changes include -28% reductions in EPA and DHA levels. After all, customers are left with something that looks like salmon, because it has been artificially colored, and tastes like "salmon", simply because 99% of the customers do not even know how "real" salmon would taste, because since the 1980s the ratio of wild-caught (real) salmon to farmed (fake ;-) Atlantic salmon has declined from 10:13 to 1:480 and fewer and fewer people have even had the chance to taste non-industrially produced salmon.