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It ain’t easy eating greens: Evidence of bias toward vegetarians and vegans from both source and target


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Sibiriak, it's interesting to know your lipids erudition!


Pine nuts are exquisite and I wish I lived in Siberia just to overindulge with them. Here they reached a cost of tens of US$ per kilo, so now I'm eating them only occasionally, to take advantage of the phytochemicals (the turpentine flavour belies something special!)



Michael Rae's approach would entail about 2% energy from ALAs, and that's not to hard to get using the appropriate foods.


What conversion rate might we expect in vegetarians and vegans? Max is about 20% I believe for EPA and 9% for DHA.


If half of max conversion is present, 2% ALAs→ 5600 mg→ 560 mg EPA + 252 mg DHA= 812 EPA+DHA, which is higher than the NIH daily recommended quantity.


So, the 2% energy ALAs suggested by Michael Rae appears to be a reasonable cautious value.


Olive oil: ingesting 30 g per day is pretty common here in Italy, and it is according to cronometer, 300 mg ALAs, which would mean a max amount (max conversion rates) of 60 mg EPA and 27 mg DHA, which seems pretty low. 

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Espresso sucks in Siberia--nobody knows how to use the Italian  machines!    Not much olive oil choice either, just a few brands imported from Italy, Spain or Greece--locals use sunflower oil mostly.   Vegetable selection not so great.   Two kinds of beans, red and white.   Excellent berries though!   I've built a diet around the best of what's  available.



it's interesting to know your lipids erudition!



I'd need a far greater mastery of physiology and biochemistry before I'd call myself erudite.

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mccoyWhat conversion rate might we expect in vegetarians and vegans? Max is about 20% I believe for EPA and 9% for DHA.



Jack Norris at VeganHealth.org has a pretty extensive discussion of the n3/ALA issue.  He cites lots of studies and data.   He ends up  recommending supplements for vegans.  His is just one more opinion,  of course,  and since I'm still eating some oily fish, I've not had to come to any hard conclusions in that regard.


The erudite Dean Pomerleau has opted for a small amount of EPA/DHA supplementation:



Michael Rae opposes EPA/DHA intake for people on CR,  in adherence to the DHA-accelerated Aging Hypothesis:




Jack Norris:



Summary of Omega-3 Benefits and Concerns


What we know about ALA is summarized in Table 11.


If it weren't for the (small chance) for potential eye problems, I would suggest either adding 3 g of ALA per day or taking DHA supplements. Because of the eye issues, that much ALA is not worth the risk when DHA supplements are available. I would still recommend adding about .5 g of ALA per day for its own benefits for heart disease and to help increase EPA levels. If using such small amounts of uncooked, plant sources of ALA the risk to the eyes should be minimal.


If you are getting the recommended ALA and DHA, EPA should not be a problem. Fish contain about twice as much DHA as EPA (27), so it's not unusual to get more DHA than EPA in the diet. But it is okay to get a supplement with EPA and DHA in it. If you get a DHA supplement with EPA in it, choose one with at least 200 mg of DHA per serving; I have no recommendations for how much EPA it should contain.


My recommendations to keep vegans about on par with fish eaters are:

Without diet planning, vegans and vegetarians have low omega-3 intakes and blood levels; and in some cases, older vegans have close to no DHA in the blood. It is not clear whether these lower blood levels are harmful (and it is not likely to be well understood any time soon). Because DHA supplements are relatively expensive we suggest two options for vegetarians under Step 1.


Step 1: DHA Suppplement


Caution: Too much omega-3s can result in bleeding and bruising. If you have reason to believe you have problems with easy bleeding or bruising, or are already consuming plenty of omega-3s, consult a health professional before following these recommendations or adding more omega-3 to your diet.

  • Option A – If you want your DHA levels to be the same as non-vegetarians, supplementing with 300 mg per day will likely accomplish that.
  • Option B – If you just want some insurance that you are getting a source of DHA in case your body isn't efficient at making it, supplementing with 200 - 300 mg every 2-3 days will provide that.
  • Vegetarians over 60 years old should err on the side of Option A.

Step 2: Minimize Omega-6 Oils

  • Do not prepare food with oils high in omega-6 such as corn, soy, safflower, sunflower, most vegetable oil blends (typically labeled "vegetable oil") and sesame oil. Instead, use low omega-6 oils like olive, avocado, peanut, or canola. Only cook canola under low heat and for short periods.

Step 3: Add some ALA


Add 0.5 g of uncooked ALA to your diet daily (see chart). This would be the equivalent of: 1/5 oz English* walnuts (3 halves)

1/4 tsp of flaxseed oil

1 tsp of canola oil

1 tsp ground flaxseeds

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Sibiriak, probably you came across the Welch et al., 2010 study:


Am J Clin Nutr. 2010 Nov;92(5):1040-51. doi: 10.3945/ajcn.2010.29457. Epub 2010 Sep 22.

Dietary intake and status of n-3 polyunsaturated fatty acids in a population of fish-eating and non-fish-eating meat-eaters, vegetarians, and vegans and the product-precursor ratio [corrected] of α-linolenic acid to long-chain n-3 polyunsaturated fatty acids: results from the EPIC-Norfolk cohort.

Where it has been observed that EPA+DHA serum levels in vegetarians and vegans who did not eat fish were not very different from the fish eaters. The authors believe that's from the adaption and the ensuing high conversion ratio ALAs→EPA+DHA. I have a problem with that study,  that is the source of ALAs is not walnuts or flaxseed, rather cereals, fatty spreads, vegetables. Maybe nuts & seeds belong to the vegetables category or spreads are nuts butters... Also, brain DHA might be different than blood DHA.
The results of this study would contradict those cited by Norris, where EPA+DHAs were much lower in vegetarians and vegans. Although, now That I'm reading it, Norris' article is pretty exhaustive. Maybe the conclusion is that the intricacies of ALAs metabolism are still not perfectly known. 
I totally agree that, in the doubt, best to eat a little fish or take some supplementation. I myself might fall back on some vegan DHA supplementation, although after the insights gained by attending this forum now I am supplying plenty ALAs to my body, but in doses far higher than those suggested by Jack Norris, who hints at potential health problems from high ALAs intake.
What can I do, I'll be on the lookout for those problems, LOL!
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Espresso sucks in Siberia--nobody knows how to use the Italian  machines!    Not much olive oil choice either, just a few brands imported from Italy, Spain or Greece--locals use sunflower oil mostly.   Vegetable selection not so great.   Two kinds of beans, red and white.   Excellent berries though!   I've built a diet around the best of what's  available.


I understand it must be hard or impossible having fresh food during the winter season. If EVOOl is IGP or DOP (Italian brands of quality) one or two tablespoons should be enough to provide an healthy polyphenol content, as per European Commission suggestions. Otherwise, as discussed in another thread, even we Italians have problems if we buy EVOO in supermarkets, there isno guarantee at all that polyphenol reach the 300 ppm threshold. What about cereals? Buckwheat must be common and good over there.


Espresso: sometimes even I could not make coffe with the classic Italian machines, whereas my wife, a coffee-addict, almost invariably could. the most common problem is that the machine only comes out half full.




Actually, there is another type of coffee machine, only used i by a few elite coffee lovers, where coffee is produced by gravity. It's called 'caffettiera napoletana', that is from Naples, where it was mainly used. 




Lately, quick espresso machines have become popular and I myself have one. In the morning, I'm able to take a cup to my wife at bed very quickly and without fuss, my missus loves it, I love it even more since it saves me lots of time! This is exactly the one I have. Only health concern is the plastic coffee container/filter.


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Thanks for the espresso machine info.  I'll probably get one at some point.   In the meantime,  I've been making coffee Greek style, with a nice thick foam,  or when I'm in a hurry,  just pouring hot water over ground coffee and agitating to create crema.


Btw, I posted some info on coffee previously, challenging Dean Pomerleau and Michael Rae's insistence that coffee should be paper filtered to avoid the cholesterol-raising effects of cafestol and kahweol.     I was hoping to have my points critiqued, but I received no response.


I cited several articles with interesting info on beneficial effects of those two diterpenes.


See the last post on this page:


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Sibiriak, I was just wondering about the anti Prostate-cancer effects of coffe and  cafestol and kahweol appear to be major contributors (even though in another article caffeine itself has been thought to check Pca occurrance). And I basically agree with your point that a corrected average increase of 6 ml/dL of cholesterol from coffee drinking is a negligible amount, especially in individuals who are already low in that score. 


About Dean's mocha illustration: the filter with the large holes which Dean illustrated in the picture you linked is actually the funnel, which prevents coffee from falling into the water vessel underneath, whereas there is a metal filter with smaller holes, though such holes most probably won't block the diterpenes molecules. I never saw in Italy paper coffee filters. Never till my memory goes back, more than half a century. 


In the following illustration, the metal filter is called 'filter plate' (# 6) and its holes are pretty small, small enough to filter all ground coffee particles, which of course must absolutely not reach the collector above.



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mccoy cafestol and kahweol appear to be major contributors (even though in another article caffeine itself has been thought to check Pca occurrance


In that post I focused only on cafestol and kahweol (lipids) because they had been identified by Dean et al.  as elements that should be filtered out because of their cholesterol-raising effect.


You are quite right that caffeine itself has been noted as an anti-cancer agent,  along with quite a few other  substances. 


(Btw, one idea to enhance the beneficial phytochemical mix in coffee is to use a combination of light and dark roasts.  Green coffee beans are also touted.)


Here's a review:

Coffee provides a natural multitarget pharmacopeia against the hallmarks of cancer  (2015)




For what it's worth, I just now noticed  another  article in my files:

Coffee consumption and prostate cancer risk and progression in the Health Professionals Follow-up Study.



It concludes:

We observed a strong inverse association between coffee consumption and risk of lethal prostate cancer. The association appears to be related to non-caffeine components of coffee.

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mccoy:  What about cereals? Buckwheat must be common and good over there.


Absolutely!   Buckwheat kasha ( гречка) is a regular part of my diet.  I also eat a good amount of rye bread and oatmeal porridge.


This is one area where I divert  from Fuhrman's dietary doctrine.   Based on his overly simplistic formula

Health = Nutrients / Calories (H = N / C),  he seems to devalue cereals (pseudo-cereals) relative to vegetables and fruits.


I believe you already discussed the practical problems involved in eating the massive amount of vegetables Fuhrman recommends.  I agree entirely.  There are also   theoretical problems in the definition,  ranking, and calculation of "nutrients" in his formula. Nutrition is a very complicated affair;  it's quite easy to go astray with ranking formulas.  Many factors can be overlooked, and much is unknown. 


Buckwheat’s beneficial effects are due to the broad spectrum of flavonoids which are biologically active phytonutrients possessing health benefits, including reduction of cholesterol [1], inhibition of tumors [2], regulation of hypertension [3], as well as control of inflammation, carcinogenesis and diabetes [4].


[...]Compared to rice and wheat, buckwheat seeds are richer in protein and antioxidants, such as phenolic compounds [5]. In experiments, D-chiro-inositol, fagopyritols (galactosyl derivatives of D-chiro-inositol), resistant starch, and buckwheat protein, all present in buckwheat, had positive health effects on rats, but further studies should be undertaken to establish their effects on humans [6].





The presence of D-fagomine in the human diet from buckwheat-based foodstuffs





Buckwheat (Fagopyrum esculentum Moench) groats contain the iminosugar D-fagomine as a minor component that might contribute to the alleged health benefits of this pseudo-cereal. This study presents analysis of D-fagomine in buckwheat-based foodstuffs by liquid chromatography coupled to mass spectrometry and an estimation of its presence in the human diet based on a published population-based cross-sectional nutrition survey. D-fagomine is present in common buckwheat-based foodstuffs in amounts ranging from 1 to 25 mg/kg or mg/L, it is stable during boiling, baking, frying and fermentation, and it is biosynthesised upon sprouting. The estimated total intake of D-fagomine resulting from a diet that includes such foodstuffs would be between 3 and 17 mg per day (mean for both genders; range from P5 to P95). A diet rich in buckwheat products would provide a daily amount of D-fagomine that may in part explain the beneficial properties traditionally attributed to buckwheat consumption.   PMID:  23194529


Consider this argument:


Health-Promoting Potential Equal to or Even Higher than that of Vegetables and Fruits


Research reported at the American Institute for Cancer Research (AICR) International Conference on Food, Nutrition and Cancer, by Rui Hai Liu, M.D., Ph.D., and his colleagues at Cornell University shows that whole grains, such as buckwheat, contain many powerful phytonutrients whose activity has gone unrecognized because research methods have overlooked them.


Despite the fact that for years researchers have been measuring the antioxidant power of a wide array of phytonutrients, they have typically measured only the "free" forms of these substances, which dissolve quickly and are immediately absorbed into the bloodstream. They have not looked at the "bound" forms, which are attached to the walls of plant cells and must be released by intestinal bacteria during digestion before they can be absorbed.


Phenolics, powerful antioxidants that work in multiple ways to prevent disease, are one major class of phytonutrients that have been widely studied. Included in this broad category are such compounds as quercetin, curcumin, ellagic acid, catechins, and many others that appear frequently in the health news.  When Dr. Liu and his colleagues measured the relative amounts of phenolics, and whether they were present in bound or free form, in common fruits and vegetables like apples, red grapes, broccoli and spinach, they found that phenolics in the "free" form averaged 76% of the total number of phenolics in these foods. In whole grains, however, "free" phenolics accounted for less than 1% of the total, while the remaining 99% were in "bound" form.


In his presentation, Dr. Liu explained that because researchers have examined whole grains with the same process used to measure antioxidants in vegetables and fruits; looking for their content of "free" phenolics"—the amount and activity of antioxidants in whole grains has been vastly underestimated.


Despite the differences in fruits', vegetables' and whole grains' content of "free" and "bound" phenolics, the total antioxidant activity in all three types of whole foods is similar, according to Dr. Liu's research. His team measured the antioxidant activity of various foods, assigning each a rating based on a formula (micromoles of vitamin C equivalent per gram). Broccoli and spinach measured 80 and 81, respectively; apple and banana measured 98 and 65; and of the whole grains tested, corn measured 181, whole wheat 77, oats 75, and brown rice 56.



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Re: coffee - If caffeine is just one and not the only or major anti-PCa compound, that's good new since decaffeinated coffee would have about the same beneficial properties. Green coffee has just started to be served in some public places here. It's good and apparently less aggressive to the stomach linings.


Re: Furhman and cereals. Dr. Fuhrman puts vegetables as the basis of diet, but other plant-based proponents, first and foremost Dr Mc Dougall, put cereals as the mainstay of an healthy vegan diet. Actually, I was skeptical but after having read one of McDougall's books and having listened to some of his podcast, there are some undoubtable truths to his statements. He puts cereals , potatoes and legumes first, then vegetables. Whereas he puts vegetables first in his maximum weight loss program. All cereals rigorously whole grain and to those who want to loose weight, he reccomands to avoid flours, bread and so on, which cause a higher insuline response. All with its scientific logic. He has a few fixations, like no fats at all, no supplements at all, but as a whole I must confess his emphasis on cereals has reasonable bases.


Re. Buckwheat. Very interesting articles on buckwheat! I myself am a fan of the very tasty cereals like buckwheat and rye. I just cannot understand like people in Italy are able to eat white, tasteless wheat bread. The stronger and tastier the cereal, the more my instinct tells me it's good, and as a matter of fact, the strong and bitterish tastes are related to a host of beneficial phytochemicals some of which have been studied in the articles you linked.

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Sibiriak, thanks for the update on LA, ALAs, ARAs.


If 1% ALAs appears to meet the requirements, that means for example, in a 2500 kCal diet, an average energy of 25 kCal → about 2.8 grams of ALAs daily on the average.


That corresponds to 30 grams of walnuts in the USDA database, about 175% RDA for myself.


1.75 tablespoons ground flaxseed also add up to 2.8 grams ALAs, with much fewer omega6.


The takeaway lessons would be something like this:


  • Take at least a coupla tbs. ground flaxseed per day
  • Eat only few walnuts, what's required to ingest some specific phytosterols (walnuts are very rich in condensed tannins, as their astringent taste testifies)
  • Eat as little as possible sunflower oil or foods containing sunflower oil and other vegetable oils (except few specific exceptions)
  • Eat sunflower seeds and pumpkin seeds in moderate amounts, to take advantage of specific phytosterols and protein and minerals in such inexpensive food
  • Eat not too much of other nuts since they increase the LAs content


I can pretty much agree with the above, without getting fixated with it though. Nuts still make up a very valuable food, so their amount should be optimized, not drastically decreased. Although the minimum amount believed to be healthy, about one ounce or 28 grams, is pretty low. I'd take at least 2 ounces or more than 50 grams minimum daily quantity of nuts and up my intake of ground flaxseed.


I find nuts too tasty and healthy not to indulge with them sometimes.


Really great discussion. I'm curious, how much fat are you all eating daily? (Both % and total would be helpful I guess.) I struggle with deciding how much fat to put in my diet. Currently at about 22-25%, 65-70g daily. I eat a tablespoon of flax daily and walnuts a few times a week. The rest comes from tofu and peanut butter usually. I haven't really thought too much about my LA intake. I decided on taking a vegan DHA supplement.

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Really great discussion. I'm curious, how much fat are you all eating daily? (Both % and total would be helpful I guess.) I struggle with deciding how much fat to put in my diet. Currently at about 22-25%, 65-70g daily. I eat a tablespoon of flax daily and walnuts a few times a week. The rest comes from tofu and peanut butter usually. I haven't really thought too much about my LA intake. I decided on taking a vegan DHA supplement.



Wise, my latest weekly average is 40% fat in calories, about twice as yours. My energy intake may seem pretty high but I'm exercising and exhibiting a slightly decreasing bodyweight trend.


Daily averages:

  • Total energy = 2790 kCal
  • Total lipids = 128 g 
  • MUFAs=52 g
  • PUFAs=32 g  
  • n-3 = 4.2 g
  • n-6 = 28 g
  • SAFAs = 34 g
  • cholesterol = 84 mg
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Well, I have to make a confession-- I'm not much of a calorie or nutrient counter!   (I hope the punishment won't be too severe.) 


I follow a certain diet —


roughly: buckwheat, rye,  some oats; beans/legumes; various nuts, particularly pistachios, some sunflower seeds; some kefir and oily fish; lots of berries-- mostly blackcurrant, lingonberry, sea buckthorn [облепиха] , but also wild strawberries, raspberries, and some unusual Siberian bitter ones.-- vegetables including Russian-style fermented vegetables, onions, garlic, mushrooms, Spanish capers, olives , dill,  parsley etc.;  fruits --mostly bananas, apples, some pomegranates,  avocados if I can ever get any; olive/camelina oil,  a little sea buckthorn oil;  honey, some bee pollen;  spices-- cayenne pepper,  turmeric, ginger, cinnamon;  tea, coffee, chicory, some dark chocolate/cacao, some red wine, dark beer, kvass!!;  a few supplements, including curcumin, rhodiola, vitamin D/K2, plus a few others to hedge bets or play around with-- more or less a gamble .... something like that...


--and add/subtract some carbs/ fats to keep a BMI around 21 w/ fairly low body fat.   I follow my intuition quite a bit in my daily eating.


With that diet/supplement regime relatively fixed (for now), I’m focusing on exercise, restricted eating time, intermittent fasting, cold exposure, pranayama...

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Regarding Olive oil in Russia:


According to euromonitor.com, the most popular oils on the Russian market are Spanish Borges and ITLV (Borges Mediterranean Group, 15,8% of the market), Italian Monini (Monini SpA, 8,4% of the market), as well as Spanish Carbonell (Deoleo SA, 10 , 2% of the market) and Maestro de Oliva (Olive Oil International sl, 8,1% of the market).

[...]St. Petersburg-based company works with a wide range of brands (Monini, Maestro de Oliva, Ibetrica, Bioitalia, Oliveto). The share of each company is 13%.


Russian consumers regard olive oil as an exclusive product, not one of mass consumption. [...]Despite their consumption of olives and olive oil, the bulk of consumers know very little about the grades and quality of olive oil and olives. [...]Olive oil is still perceived as a gourmet product and for people who are concerned with their health.


[...]In 2002 the Ministries of Agriculture of Spain, Italy and Greece combined to promote olive oil in Russia with a massive advertising campaign promoting their product. This campaign has already yielded results: Spanish, Italian and Greek oil hold the leading position in the Russian market, maintaining their regular customers and attracting new clientele.


[...] Most of the olive oil is sold in glass bottles; however glass creates a sensation of elitism and inaccessibility for the Russian consumer. The use of tin remains affordable as does the use of plastic bottles and it is hoped that producers will use this packaging in the future. .




I've been using the Spanish ITLV or Maestro de Oliva recently.  They did seem to have some pepperiness, which  hopefully indicates some polyphenol content.  I just use a little.


Of course,  I really should and really do want to use good Italian olive oil!!   So that's something I need to look into.

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Sibiriak, I only recently, after becoming a member of this forum, could really appreciate the importance of the polyphenol content of EVOO.


In Italy, providing that acidity and some other government-regulated properties are satisfied, taste governs, regardless of polyphenols content.

The result is that such parameter is not on labels and is not always easy to know it.  For example, I don't know the polyphenols in my present stock, so as soon as I have time I'll have to pay an official lab to have it analyzed.


Also, since good taste is not significantly compromised with time, in Italy there is request of previous year EVOO, whereas as per info collected in this forum polyphenols degrade with time so EVOO should rigorously be from the latest crop.


By the way, where are you from in Siberia? That's not exactly a small region!

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Mccoy,  I'm in Krasnoyarsk, on the periphery of the city,


That's a fascinating city, and place. I also looked up the temperatures, even Wim Hof, the iceman himself, would have problems in the coldest winter with -58 °C !

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It's a warm  -4 C  right now.   Beautiful thick snow.  Last snow until  fall, probably. 


One thing nice:  the tap water comes from the Yenisei river and is ice cold year round.     Great for icy cold showers/baths.   Really  cold.


Wikipedia:  Very few major cities on earth have higher differentials between summer and winter temperatures than Krasnoyarsk.

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mccoy: What conversion rate might we expect in vegetarians and vegans? Max is about 20% I believe for EPA and 9% for DHA.  If half of max conversion is present, 2% ALAs→ 5600 mg→ 560 mg EPA + 252 mg DHA= 812 EPA+DHA, which is higher than the NIH daily recommended quantity.


Also, brain DHA might be different than blood DHA.  [...]Maybe the conclusion is that the intricacies of ALAs metabolism are still not perfectly known.


I decided to take another look into the ALA conversion issue,  and the more I look into the more complex and uncertain the whole issue becomes.  It also make me wonder about the wisdom in doing speculative calculations based on such imperfect information.


[As an aside,  it has always struck me as odd from an evolutionary standpoint that humans would NEED to eat fish or fish oil to maintain optimum health.]


As far as the conversion rates are concerned, it appears that the 9% figure for DHA is a real outlier, and that:

Stable isotope methods have typically resulted in estimates of percent conversion of ALA to DHA being less than 1% of the ingested stable-isotope ALA, although estimates vary widely, ranging from 0–9.2% (Table 1). Also, there is typically no increase in plasma total lipid or phospholipid DHA when ALA intake is increased in humans (reviewed in [10] ;  [11]), supporting the conclusion that DHA synthesis from ingested ALA is not an efficient process in humans.



But that all may be largely irrelevant when the complexities of  DHA uptake into the brain are taken into consideration.  The following review really gets deep into the issue of ALA conversion and brain DHA requirements.    It’s a must read, imo.


Is docosahexaenoic acid synthesis from α-linolenic acid sufficient to supply the adult brain?



A few quotes:


Recommendations for daily intake of EPA and DHA for primary prevention of coronary heart disease range from 200 to 3000 mg/d (reviewed in [29]), but we are not aware of any specific recommendations regarding DHA intakes pertaining to the adult brain.


This review critically examines the methodologies used to estimate DHA synthesis from ALA in humans and presents evidence suggesting that DHA synthesis capacity in humans may be greater than previously estimated. Studies measuring DHA synthesis in adult humans will also be reviewed in the context of the brain. Additionally, a novel technique to measure DHA synthesis, that can be used in humans, the steady-state infusion method, is presented and evaluated as a means to determine, for the first time, a quantitative DHA synthesis-secretion rate in adult humans. In 2009, Barcelo-Coblijn and Murphy elegantly argued that ALA is a significant contributor to tissue DHA [25]. Herein, we provide an update of the literature with a focus on brain DHA homeostasis.


Based on the model that plasma unesterified DHA is the major DHA pool that enters the brain, brain DHA uptake rates in the rat can be measured by infusing radiolabeled unesterified-DHA and measuring how much gets incorporated into the brain, after correcting for plasma radioactivity (i.e. brain exposure to radioactivity) and the pool size [62]. More recently, this concept was applied to humans using positron emission tomography to image the incorporation of [1-11C]-DHA into the brain and quantify a rate of DHA uptake into the brain [63]. The rate of DHA uptake into the brain is assumed to be replacing DHA that is consumed in the brain, and therefore, can be used as an estimate for the brain DHA requirement. It has been reported that the brain DHA uptake rate in humans is between 2.4 and 3.8 mg/day [63] ;  [64]. Based on current estimates of ALA consumption in adult males of 1700 mg/day, the percent conversion of ALA to DHA would need to be 0.14–0.22% to match the brain DHA requirement [65]. Therefore, it is possible that even a small amount of DHA synthesis may be sufficient to meet adult brain DHA uptake demands.


Recently, alternative mechanisms for DHA synthesis have been proposed [84]; [93]; [94] ;  [95]. An experiment performed in baboons determined that the Δ6-desaturase enzyme also has Δ8-desaturase activity [93]. Based on this finding the authors proposed an alternative pathway for DHA synthesis from ALA that functions in parallel with the classical pathway and involves an initial elongation of ALA to 20:3n-3 followed by Δ8-desaturation to make 20:4n-3, which is then desaturated and elongated to become DHA [93]. Another recent study questioned the Δ6-desaturation as the sole rate-limiting step in the synthesis pathway. The authors found that the elongation of DPA n-3 to 24:5n-3 may be another crucial control point in DHA synthesis [94]. This reaction is catalyzed by the enzyme elovl2, and lack of expression of this enzyme in heart is believed to be the reason why heart tissue has very low DHA synthesis rates [96]. These novel insights into DHA synthesis merit further investigation to determine how much they contribute to DHA synthesis in vivo.


While most studies report that plasma and erythrocyte EPA increase with ALA feeding, most do not detect an increase in plasma or erythrocyte DHA [98]; [99]; [100]; [101]; [102]; [103]; [104]; [105]; [106]; [107]; [108]; [109]; [110]; [111]; [112]; [113]; [114]; [115]; [116] ;  [117]. Reviews of these studies have pointed out two important points pertaining to the lack of plasma DHA increases after ALA feeding. Firstly, in humans with low DHA diets (vegans and vegetarians), ALA feeding increases plasma DHA [97]. Additionally, plasma DHA tends to increase to a greater extent when ALA consumption is increased in combination with decreased LNA consumption [10] ;  [11].


It should be recognized that these studies only measure DHA in blood lipids (plasma, erythrocytes, or leukocytes) as opposed to tissues. While plasma DHA may be a reliable marker for dietary DHA intake, the applicability of this pool to the brain is not agreed upon. This is because most of these studies measure percent composition of DHA in the esterified blood lipid pools, which are not thought to be available to the brain [62]. A recent rodent study performed in our laboratory highlights this point [66]. We fed rats a diet that was either low in n-3 PUFA (0.25% fatty acids as ALA) or contained either ALA or DHA. After 15 weeks on these diets, levels of DHA in the body and plasma were significantly higher in rats fed DHA compared to rats fed the ALA and control diet (2.4 and 11-fold higher, respectively, for the body and 2 and 5-fold higher, respectively, for plasma). However, brain DHA levels were not different between ALA- and DHA-fed rats, similar to previous studies in rats [19] and non-human primates [20], suggesting that changes in blood DHA concentration do not necessarily reflect the magnitude of changes in brain DHA, with some exceptions [118] ;  [119]. Interestingly, graded ALA deprivation from 4.6% (considered “adequate” to maintain brain function and DHA concentrations) to 0.2% (considered “inadequate” based on decreased DHA concentration and metabolism) of fatty acids in a diet lacking DHA results in decreased brain DHA only when the ALA content of the diet is decreased to 0.8% or lower [120]. This indicates that extreme cases of ALA deprivation are required to affect brain DHA concentrations.


It is possible that though plasma esterified DHA is unchanged with chronic increases in ALA feeding, dietary ALA may be sufficient to maintain brain DHA concentrations, possibly via the plasma unesterified fatty acid pool. The plasma unesterified fatty acid pool is 10–100-fold smaller than the esterified pools [89]; [121] ;  [122] and is maintained largely via the adipose (fasting state) and hydrolysis from plasma lipoproteins (post-prandial) [123]. Also, the DHA concentration of the plasma unesterified fatty acid pool decreases only when extreme n-3 PUFA deprivation occurs [120]. Moreover, few studies have examined the effect of increasing dietary DHA intake on unesterified DHA concentrations in humans, with some studies reporting an increase and others reporting no increase [76]; [121]; [124]; [125]; [126] ;  [127]. Adipose, the tissue that maintains plasma unesterified fatty acid concentrations, has been estimated to contain 1–4 and 20–50 g of DHA in the infant [128] ;  [129] and adult [130], respectively. Using the previously measured brain DHA uptake rate of 3.8 mg/day in adult humans, it can be calculated that adult human adipose contains enough DHA to supply the brain for 14–36 years. It is important to note that the estimate for how long adipose DHA can supply the brain is an overestimate because DHA released from the adipose is used by other tissues as well as the brain. Therefore, to determine the actual amount of time that adipose DHA can supply the brain, the proportion of DHA that is released from the adipose and taken up into the brain (brain-body partition coefficient) must be determined.

There is considerable debate as to whether the human capacity to synthesize DHA from ALA is sufficient to meet brain DHA requirements. This debate has been further complicated by lack of agreement regarding the brain DHA requirement, and methodological inconsistencies in attempts to quantify the rate of DHA synthesis from ALA. The IOM did not assign a dietary reference intake for DHA, and other recommendations for DHA and EPA intake pertain to cardiovascular disease prevention [27]; [29]; [174] ;  [175] and not specifically to support the brain, in part reflecting uncertainty in the role of dietary DHA in maintaining brain DHA. Fortunately, an estimate of human brain DHA uptake is now available (2.4–3.8 mg/day [63] ;  [64]), and novel approaches to measure whole-body DHA synthesis from serum ALA using steady-state isotope infusion will allow for quantitative comparison of DHA synthesis rates to brain DHA uptake rates, as done previously in rats [66]. This approach will supplement previous measurements of DHA synthesis from ingested stable isotope ALA, which provide estimates of DHA synthesis from postprandial ALA, and produce a more complete understanding of DHA homeostasis in humans.Despite limitations in comparing rates of DHA synthesis and brain DHA uptake rates in humans to date, there is considerable evidence from animals showing that brain DHA levels are similar when fed ALA as the only n-3 PUFA as opposed to DHA or ALA+DHA, as reviewed extensively by [65], although there are some exceptions [119] possibly related to dose-, duration-, and species-specific effects. The brain has mechanisms whereby it can conserve DHA that may explain similar brain DHA between DHA- and ALA-fed rats [176].


See also:


The effect of linoleic acid on the whole body synthesis rates of polyunsaturated fatty acids from α-linolenic acid and linoleic acid in free-living rats



Whole body synthesis rates of DHA from α-linolenic acid are greater than brain DHA accretion and uptake rates in adult rats



Plasma non-esterified docosahexaenoic acid is the major pool supplying the brain


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Hi Sibiriak!


Several things: 


(1) Evolutionary explanation of the human need for fish oil (w3's -- essential fatty acids).  The predominant view among anthropologist is that man evolved in an environment very rich in water (e.g., we need A LOT of water daily -- more than typical land mammals -- and lose a lot daily though sweating --  suggesting that our immediate evolutionary ancestors lived near a source of fresh water (perhaps on the shores of a lake, or river) -- and therefore, our ancestors probably ate fish, or seafood, which was so available.  Hence, we didn't need to be able to manufacture the essential fatty acids from other fatty acids -- we had them from fish or seafood).


(2)  Concerning the conversion of ALA to long chain w3's:  According to the physicians with whom I have talked, such conversion varies very greatly among individuals.  So no simple rule fits all (this was also discussed on the old CR mailing List in the past).


  --  Saul

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Sibiriak: very interesting article, which would at least partly explain why vegans and vegetarians who haven't been eating fish for decades (like myself) apparently are not deleteriously afflicted by the lack of fish and seafood. It also would agree with your previous hunch that omega-3s are stored somewhere. The human must have built a strategy to provide such a valuable brain nutrient like DHA in places and times where there was no fish and possibly little ALAs.

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Gordo:  I wish they would repeat the study using vegan DHA (algae based) ...

[...]  I get all my EPA from plant foods so I'm not concerned about that, but not completely sure I'm getting enough DHA

While not a comparison with salmon,  this study suggests that vegans  respond well to algae-basedA/DHA supplements:

Blood docosahexaenoic acid and eicosapentaenoic acid in vegans: Associations with age and gender and effects of an algal-derived omega-3 fatty acid supplement.  (2015)





Several studies have demonstrated that vegetarians and vegans have much lower plasma concentrations of omega-3 fatty acids (i.e., docosahexaenoic and eicosapentaenoic acids) when compared to those who eat fish. The purposes of this study were 1) to define the age and/or sex-specific docosahexaenoic plus eicosapentaenoic acids levels in red blood cell membranes (expressed as a percent of total fatty acids; hereafter the omega-3 index) in long-term vegans, and 2) to determine the effects of a vegetarian omega-3 supplement (254 mg docosahexaenoic plus eicosapentaenoic acids/day for 4 months) on the omega-3 index.



A sample (n = 165) of vegans was recruited, and their omega-3 index was determined using a dried blood spot methodology. A subset of 46 subjects with a baseline omega-3 index of <4% was given a vegetarian omega-3 supplement for 4 months and then retested.



The mean ± SD omega-3 index was 3.7 ± 1.0% which was similar to that of a cohort of omnivores (deployed US soldiers) from a recently-reported study. Among the vegan cohort, the index was significantly higher in females than males (3.9 ± 1.0% vs. 3.5 ± 1.0%; p = 0.026) and was directly related to age (p for trend = 0.009). The omega-3 index increased from 3.1 ± 0.6% to 4.8 ± 0.8% (p = 0.009) in the supplementation study.



We conclude that vegans have low baseline omega-3 levels, but not lower than omnivores who also consume very little docosahexaenoic and eicosapentaenoic acids. The vegans responded robustly to a relatively low dose of a vegetarian omega-3 supplement. 


In Phase 2, we found that a relatively low dose of EPA + DHA  (243 mg per day) significantly raised the omega-3 index. The mean absolute increase here was 1.7% over 4 months. This compares favorably to an observed increase of 1.8% in a group of 23 omnivores given 300 mg EPA þ DHA for 5 months.23 In another study, 850 mg of EPA þ DHA ethyl esters raised the omega-3 index by 1.5% after 2 months of supplementation.24 Although not head-to-head studies, blood samples were measured using the same method in all 3 of these studies.


In a German study with an algal DHA-only supplement, 940 mg/d for 2 months was reported to raise the omega-3 index from 4.8% to 8.4% in 87 vegetarians.15 All of these findings suggest that vegans respond to supplemental omega-3 fatty acids in the same way that omnivores do.


...our fatty acid intake data may be questionable although the intakes we report are reasonable for vegans. There was no objective

measure of adherence to the supplementation guidelines in Phase 2.

Since subjects were taking their omega-3 fatty acids by eyedropper, actual doses likely varied considerably, and how, exactly the subjects consumed the dose of <1 mL per day is also unknown (i.e., directly on the tongue, mixed in other foods, dispersed in juice, etc.).


We conclude that a majority of long-term vegans appear to be relatively deficient in DHA and EPA, but whether this leads to adverse health consequences is unclear. It is possible that low-dose supplementation with algae-sourced DHA and EPA may mitigate the potential adverse effects of deficiency in this population. All of these issues require additional investigation.





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mccoy: I just cannot understand like people in Italy are able to eat white, tasteless wheat bread.




Well, my only experience of Italy was three weeks in and around Rapallo,  but the people there did seem to be able to put some pretty tasty stuff on top of the tasteless white bread,  which certainly helped it go down. 


For example, focaccia di Recco cotta in forno ripiena di formaggio e successivamente ricoperta di pesto genovese ancora calda.






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Sibiriak, I agree that lots of cheese and pesto improve the basic white flour dough, but just imagine how that focaccia would have tasted in a buckwheat version! 


Actually, there are some local recipes like pizzoccheri della Valtellina (an Alpine valley) which is buckwheat pasta where you feel the difference from white pasta. And they come together with cabbage (and cheese, although it's easy to prepare a vegan variation).





I do not regard white pasta a food, even though abundantly dressed.

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