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Rapid Responses: Rapid Responses published:
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Response to Dr.Trichopoulou. COX substrates: omega-6 in Mediterranean diet
- Eddie Vos (8 June 2005)
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Omega-6 and omega-3 in Mediterranean diet
- Ellen C G Grant (9 June 2005)
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Re: Omega-6 and omega-3 in Mediterranean diet
- Eddie Vos (10 June 2005)
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Re: Omega-6 and omega-3 PUFA intake and deficiencies in red blood cells
- Ellen C G Grant (10 June 2005)
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Eddie Is Right
- Dr. Herbert H. Nehrlich (10 June 2005)
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Diet, science and survival
- Ellen C G Grant (13 June 2005)
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Eddie Vos, maintains health-heart.org Sutton (Qc) Canada J0E 2K0
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I thank Dr. Trichopoulou for her kind response and
she is right about the common misconception that Cretans, who arguably gave birth to the concept of the "healthy
mediterranean diet" through the Seven Countries Study, ate lots of fish.
My point was not fish but about the central role of plant based omega-3 in traditional crete and here I translate from French (ref. 1) citing early work by A. Kafatos, University of Crete and Seven Countries collaborator: "Hundreds of wild plant species [providing plant based omega-3, alpha-linolenic acid, or ALA] rich in ALA inhabit the island, and are frequently eaten by Cretans, as salad or raw. Domesticated and wild animals eat these plants and this nutriment [ALA] concentrates not only in the meat but also in the milk and eggs of these animals. Analysis made by our team show ALA from 0.77% - 1.4% in Cretan goat milk while only 0.54% is found in goat milk from the Bordeau region. Cretans are the largest consumers of snails in the world. Cretan snails have double the ALA of French snails (9.7 vs. 4.9% of the fatty acids). Therefore Cretans have an intake of ALA that is much more important than other populations, .." .. "Cretans .. eat fish [only] 2 times per month, on average". In fact, from the same reference and regarding the Seven Countries study, the ALA in cholesterol esters in Cretans was 3x that of study participants in Zutphen, Netherlands (1). While one may propose that olive oil is a central beneficial component of "Mediterranean diets", it is arguably a proportionally excessive source of omega-6 and certainly a poor source of omega-3 [USDA: ratio 12:1 with omega-3 0.8% of the fatty acids, i.e. similar to U.S. lard with a ratio of 18:1 and 1% ALA (2)], and it is thus the plant-based omega-3 from other sources that appears as the beneficial fatty acid factor in "Seven Countries" Crete. The same is true in the Lyon intervention study, and where no differences in the common lipid and other cardio biomarkers were found and where by far the greatest finding was the large relative increase in serum ALA, as well as, of course, the unique benefit in second heart attacks and increased survival. Clearly, we should base ourselves on studies where blood fatty acids were measured and not on epidemiology where blood fatty acids go unmentioned and thus the suggestion that "vegetable lipids in general may have beneficial effects" based on a Polish food availability study (Trichopoulou ref. #3) is hard to understand. Interfering with the eicosanoids with drugs or by changing the (either omega-6 or omega-3) substrate ratio for the cyclooxygenase (COX) enzymes has opposing, unpredictable and profound effects as the recent "Vioxx story" has taught us (less pain and inflammation vs. more heart attack deaths). The overwhelming use of sunflower oil in much of the former East Block area is ominous since it contains 66% omega-6 and no detectable omega-3 [(2), item 04506], and is no justification for adding 'polyunsaturates' to the numerator of a Mediterranean diet score. In fact, the suggested beneficial high polyunsaturated but low saturated fat intake in another Mediterranean country underlies the 'Israeli Paradox' (3) with, from the abstract: "Thus, rather than being beneficial, high omega-6 PUFA [polyunsaturated fatty acid] diets may have some long-term side effects, within the cluster of hyperinsulinemia, atherosclerosis and tumorigenesis. ALL intervention studies showing all-cause mortality benefit were with plant or fish based omega-3s, NONE were with plant based omega-6. It is time we learn and appreciate the difference. vos@health-heart.org 1. Lanzmann-Petithory D, Henry O, Renaud S. Intérêt du dosage des acides gras plasmatiques comme marqueur de risque. Cardinale Feb. 2005, XVII (2): 18-20. 2. USDA food data base search www.nal.usda.gov/fnic/foodcomp/search/ [accessed 2005-6-3] 3. Yam D, Eliraz A, Berry EM. Diet and disease--the Israeli paradox: possible dangers of a high omega-6 polyunsaturated fatty acid diet. Isr J Med Sci. 1996 Nov;32(11):1134-43. Medline: 8960090. Competing interests: None declared |
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Ellen C G Grant, physician Kingston-upon-Thames, KT2 7JU, UK
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Eddie Vos writes, “Clearly, we should base ourselves on studies where blood fatty acids were measured and not on epidemiology where blood fatty acids go unmentioned”. However, he continues to ignore the fact that both omega-6 and omega-3 deficiencies are common when levels are measured.1 US expert Dr Edward Seguel, who developed laboratory analyses of fatty acids in blood and fat, wrote that in Western societies like the US and probably Europe, there are individuals with w6 and w3 deficiencies (many), but the number of w3 deficiencies is usually greater, as in the Framingham Heart Study.2 The results of Biolab’s Red Blood Cell Essential Fatty Acid (EFA) Profiles for of patients screened in 1990 and 2005 found a large increase in the percentage of women with omega-3 deficiencies (from 25% to 90%) but more women tested also had omega-6 deficiencies(from 25% to 60%).3 If either omega-3 EFAs or omega-6 EFAs are deficient, saturated fats are usually elevated, even in children. Repletion of mineral and vitamin co- factors and omega-3 and omega-6 deficiencies lowers the levels of saturated fats, such as stearic acid (beef fat). 1 Vos E. Response to Dr.Trichopoupou. COX substrates: omega-6 in Mediterranean diet bmj.com, 8 Jun 2005 2 Siguel E. Measuring Fatty Acids http://bmj.com/cgi/eletters/330/7498/991#107906, 25 May 2005 3 Grant ECG. Re: Measuring Fatty Acids - Possible increases in omega- 3 and omega-6 deficiencies among women http://bmj.com/cgi/eletters/330/7498/991#108033, 27 May 2005 Competing interests: None declared |
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Eddie Vos, maintains health-heart.org Sutton (Qc) Canada J0E 2K0
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Dear Dr. Grant, just like there are 3 main omega-3's from plant and fish with differing roles and 3 different chain lengths and where we agree we find 3 different and complementary roles [and general deficiencies in 'westernized' populations], there are arguably 3 main and differing omega- 6es: 1. The C18:3n-6 rare gamma-linolenic acid, found in borage and primrose oils, and where one may argue deficiency and therapeutic use. 2. The C18:2n-6 polyunsaturate linoleic acid (LA) where there is no known deficiency if not a global overload since solvent extraction of oils and corn and soy based agriculture. It is about this fatty acid your reference E. Siguel -not Seguel- wrote 10 years ago in AJCN: "Does linoleic acid contribute [sic] to coronary artery disease?" It is this fatty acid that the 'modified Mediterranean diet' authors effectively added to the numerator of their diet score and against which I argued. 3. The C20:4n-6 arachidonic acid and major brain fatty acid and mother of the main omega-6 based eicosanoids, and vital in early brain development, and abundant in meats. I submit it is therefore imprecise if not somewhat misleading to suggest that about half of the population is deficient in 'omega-6', i.e your May 28 2005 Rapid Response on eBMJ: "60% of women patients had some omega-6 EFAs [Essential Fatty Acid] deficiencies in 2005." without specifying the word 'some' and regarding what condition and standard. The argument is made by S.C. Cunnane that only plant based omega-3 is technically an EFA in all humans in all conditions. Evidently other fatty acids play important roles but few would disagree that most 'westernized' population omega-6 linoleic acid intakes exceed ISSFAL's 1999 proposed 3% of energy Upper Limit by a factor 2 or more, and that this may well underlie degenerative long-latency diseases and health problems: http://www.issfal.org.uk/adequateintakes.htm . Competing interests: None declared |
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Ellen C G Grant, physician and medical gynaecologist Kingston-upon-Thames, KT2 7JU, UK
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The International Society for the Study of Fats and Lipids (ISSFAL) states that "after much discussion" consensus was reached on the importance of reducing the omega-6 polyunsaturated fatty acids (PUFAs) even as the omega-3 PUFAs are increased in the diet of adults and newborns for optimal brain and cardiovascular health and function.1 Linoleic Acid (LA) can be converted to arachidonic acid (AA) and the enzyme, delta-6 desaturase, necessary to desaturate it, is the same one necessary to desaturate alpha linolenic acid (ALA), the parent compound of the omega-3 class and that each competes with the other for this desaturase. However, absorption and the status of enzyme co-factors is also help to determines PUFA levels. The ISSFAL summary only gives recommended intake amounts of PUFAs. When red blood cell PUFA levels are actually measured in couples complaining of unexplained infertility or unexplained recurrent miscarriages, who often have few other health complaints, deficiencies of zinc and magnesium or copper excess or deficiency are very common. These co-factor upsets often impair the functions of the enzyme delta-6 desaturase and cause omega-6 and omega-3 deficiencies. Das proposes that EFAs and their metabolites could be useful in the prevention and management of acquired immunodeficiency syndrome (AIDS). LA and AA inactivate enveloped viruses, linolenic acid-enriched macrophages are markedly tumoricidal, EFAs activate macrophages and neutrophils and induce free radical generation; and cytokines bring about some of their actions by inducing the release of EFAs; gamma-linolenic acid (GLA) and eicosapentaenoic acid (EPA) prevent genetic damage and have tumoricidal actions as well; and are relatively non-toxic when administered orally or parentarally over long periods of time. It is important that both parents have adequate amounts of essential nutrients and omega-6 and omega-3 EFAs before conception in my experience to prevent unexplained infertility and recurrent miscarriages. 1 http://www.issfal.org.uk/adequateintakes.htm . 2 Das UN. Essential fatty acids and acquired immunodeficiency syndrome. Med Sci Monit. 2005 Jun;11(6):RA206-211. Epub 2005 May Competing interests: None declared |
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Dr. Herbert H. Nehrlich, Private Practice Bribie Island, Australia 4507
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I totally agree with Eddie Vos. In addition I would like to stick out my neck, past those of the so-called experts, and say that I believe that it would be almost impossible to find a person in the claws of modern medical care or in "civilised society" to be requiring omega-6 . Omega six (n-6)are abundant in our foods, even in the junk foods preferred by our teenagers. I will not go into the tumorigenesis of n-6 as compared to n-3 but suffice it to say that the hilarious hype about dangers of saturated fats has drowned out most rational debate about the real fats, and that confusion is the best term to describe the present situation. Cretan and "mediterannean" diet notwithstanding, I propose that we will be better off without our "experts" and are well advised to return to the traditions of our forefathers. Competing interests: None declared |
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Ellen C G Grant, Physician Kingston-upon-Thames, KT2 7JU, UK
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The beauty of Science is that it is not about “Consensus opinions” but about measurable and reproducible data. Competing interests: None declared |
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