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A few points to ponder
- Archie Robertson, Anne Robertson (25 March 2006)
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Omega-3 fatty acids and blood rheology.
- L Leslie O Simpson (27 March 2006)
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What About Algae Oil?
- Kevin G. Thompson (27 March 2006)
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Role of Omega-3 Fatty Acids in Autoimmune Diseases
- Prasanta Padhan (28 March 2006)
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Fish oil benefits: flawed intelligence on toxins of mass consumption
- Gillian E Caughey, Michael J. James, Susanna M. Proudman and Leslie G. Cleland (31 March 2006)
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There's a hole in the bucket.
- David E. Brown, Kalispell, Montana 59901 (1 April 2006)
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Eco-Medicine
- carron s scrimgeour (3 April 2006)
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Re: A few points to ponder
- Eddie Vos (3 April 2006)
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Alternative sources of omega 3
- Anna C Goodman (3 April 2006)
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Ensuring a future supply of healthy fish and omega-3s
- John Balbus, MD, MPH, Timothy Fitzgerald, Scientist (22 April 2006)
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Archie Robertson, Teacher and translator specialising in science 60560 Orry la Ville, France, Anne Robertson
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In the cohort studies, was any account taken of other dietary advice, e.g. "avoid butter and other animal fats"? If such advice was given, was there any measurement of the intake of trans or hydrogenated fats, which are now widely believed to contribute or even cause arterial plaque deposits? Was the quality of fish consumed considered in any way? For example, much farmed salmon has been shown to contain little or no omega-3 of any sort. The control groups may have had a higher intake of omega-3 than was realised, through eating such foods as grass-fed beef, free-range eggs, and organic dairy products. Were this the case, it would certainly have masked any overall effects. Why in the one study where dosage levels were reported were the doses used so low? They could be insignificant relative to the rest of each individual's diet. FInally, why was so much emphasis put on fish oil? Although it is a rich source of long-chain omega-3, it is far from the only source (see above). Your Health! Anne & Archie Competing interests: None declared |
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L Leslie O Simpson, retired medical research worker Dunedin, New Zealand, 9001
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Unfortunately, it seems that the meta-analysis was based upon an erroneous concept and failed to produce significant information. Perhaps the most significant aspect of the editorial was the lack of any indication that the author was aware of the extent of the literature which indicates that altered blood rheology plays an important role in the pathophysiology of coronary heart disease. Therefore it is not surprising that there was a failure to recognise the published information which shows how eicosapentaenoic acid is involved in blood rheology, As early as 1983, Terano et al (1)reported that purified eicosapentaenoic acid in healthy subjects, lowered blood viscosity and improved red cell deformability. In a similar study two years later, Cartwright et al (2)reported the results of healthy subjects taking 3 gms daily of omega-3 fatty acids. A significant increase in red cell deformability was noted. They concluded, " Since plasma viscosity and haematocrit were unchanged, it seems likely that the effects on blood rheology were mediated by changes in erythrocyte lipid fluidity. Modification of blood rheology by dietary omega-3 fatty acids is of potential value in the treatment of vascular disease." The concept of "changes in erythrocyte lipid fluidity" was confirmed by Kamada et al (3) by means of a spin-label technique which showed that dietary sardine oil increased erythrocyte lipid fluidity. The contribution to health of this concept was confirmed by Kromhout et al (4) who showed that eating 35 grams of fish daily, led to a 50% reduction in coronary heart disease in a 20 year followup. It should be emphasised that as there is a great variability of omega-3 content of different species of fish, this is not just a matter of increasing fish intake. All of these reports need to considered from the viewpoints presented by Mayer (1964) "Blood viscosity in healthy subjects and patients with coronary heart disease," and by Lansjoen (1966) " Blood viscosity in acute myocardial infarction." In the face of the well established fact that the ingestion of fish oil improves blood rheology, it is unclear why a meta-analysis should focus on the anti-arrhythmic effects of omega-3. However, it is important to recognise that with increasing age and in the presence of some chronic disorders,the enzyme which catalyses the elongation of alphalinolenic acid to eicosapentaenoic acid (delta-6- desaturase) becomes increaseingly ineffective and dysfunctional. For that reason the availability of eicosapentaenoic acid will be reduced, and dietary alphalinolenic acid will not be utilizable. In contrast, fish oil provides the eicosapentaenoic acid which cannot be synsthesised. Because altered blood rheology is a common feature of many chronic disorders, many patients can expect to benefit from dietary supplements of 3 to 6 grams of fish oil daily. References. 1.Terano T, Hirai A, Hamazaki T, Kobayashi S, Fujuta T, Tamura Y, Kumagai A. Effects of oral administration of highly purified eicosapentaenoic acid on platelet function, blood viscosity and red cell deformability in healthy subjects. Atherosclerosis 1983;46:321-31. 2.Cartwright IJ, Pockley AG, Galloway JH, Greaves M, Preston FE. The effects of dietary omega-3 polyunsaturated fatty acids on erythrocyte membrane phospholipids, erythrocyte deformabilty and blood viscosity in healthy volunteers. Atherosclerosis 1985;55:267-81. 3.Kamada T, Yamashita T, Baba Y, Kai M, Setoyama S, Chuman Y, Otsyi S. Dietary sardine oil increases erythrocyte fluidity in diabetic patients. Diabetes 1986;35:604-11. 4.Kromhout D, Bosschieter EB, de Lezanne Coulander C. The inverse relation between fish consumption and 20 year mortality from coronary heart disease. N Engl J Med 1985; 312:1205-9. Competing interests: None declared |
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Kevin G. Thompson, Manager NA, 90079
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Your research focused on fish oil as the primary source of long-chain omega-3s while an equally important source is available from algae and it doesn't have toxins or pollutants that are associated with fish. In the US, algal oil is the only FDA approved source of DHA for use in infant formula. The approved algal oil is free from contaminants that might come from fish or fish oil. It would be much more interesting to compare fish oil supplements to algal oil DHA supplements and look at the health benefits of each. Competing interests: None declared |
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Prasanta Padhan, MD Internal Medicine JIPMER,PONDICHERRY,INDIA.605006
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Dear editor, The study by Hooper L et al draws attention to uncertainties about some of the health benefits attributed to omega 3 fats(1).However this should not underestimate the value of omega-3 fats in autoimmune and inflammatory diseases.Diseases such as rheumatoid arthritis, Crohn’s disease, ulcerative colitis ,psoriasis and lupus erythematosis are autoimmune diseases characterized by a high level of IL-1 and the proinflammatory leukotriene LTB4 produced by omega-6 fatty acids.The eicosanoids from the omega-6 and omega-3 fatty acids have opposing properties.Various studies indicate that omega-3 fatty acids have anti- inflammatory properties and, therefore,found to be useful in the management of inflammatory and autoimmune diseases in humans, including rheumatoid arthritis, Crohn’s disease, ulcerative colitis, psoriasis, lupus erythematosus, multiple sclerosis and migraine headaches(2). (1)Hooper L,Thompson RL,Harrison RA,Summerbell CD,Ness AR, Moore HJ, et al.Risks and benefits of omega3 fats for mortality, cardiovascular disease and cancer: a systematic review. BMJ 2006. [Epub ahead of print; doi = 10.1136/bmj.38755.366331.2F]. (2)Simopoulos AP. Omega-3 fatty acids in inflammation and autoimmune diseases. J Am Coll Nutr 2002;21,495-505. Competing interests: None declared |
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Gillian E Caughey, PostDoctoral Research Fellow Rheumatology Unit, Royal Adelaide Hospital, Adelaide, Australia, 5000, Michael J. James, Susanna M. Proudman and Leslie G. Cleland
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Hooper et al. (1) in a representation of an earlier analysis (2) address the risks and benefits of omega-3 fats. Both the report (1) and the accompanying editorial mention the possibility of harm from fish or fish oil due to contaminants such as methylmercury, dioxins and dioxin like polychlorinated biphenyls (PCBs). We have a longstanding interest in the anti-inflammatory effects of fish oil. To achieve anti-inflammatory doses economically we advise patients to take 15mls fish oil daily on juice (equivalent to 14 standard capsules daily) (3). The product, from Berg LipidTech (Aalesund, Norway) contains eicosapentaenoic acid (EPA) 18% w/w and docosahexaenoic acid (DHA) 12% w/w. Third party analysis showed dioxins and indicator PCBs, which can be reduced by molecular distillation during processing of fish oil, to be below the level of detection and mercury present at 0.006mg/kg. We have analysed mercury levels in both urine and blood in rheumatoid arthritis (RA) patients who had taken fish oil 15ml/day for at least 3 years (mean 5.3 yr, range 3.7-6.7yr). Compliance was confirmed by questionnaire and plasma omega-3 fatty acid analysis - plasma phospholipid EPA > 5% of total fatty acids cf. 0.9% in RA patients not taking fish oil. In all cases mercury levels were low within the normal reference range and in most cases at or below the limit of detection (Table).
In evaluating the risks of fish oil one needs to consider the hazards of treatments it displaces. In RA, taking fish oil has been associated with approximately 50% reduction in discretionary NSAID use (4). Long term studies of NSAIDs in RA show rates of serious upper GI haemorrhage or myocardial infarction combined, can occur in 2% of patients per year (5). This collateral damage clearly outweighs any likely hazards associated with fish oil use. References 1. Hooper L, Thompson RL, Harrison RA, Summerbell CD, Ness AR, Moore HJ, et al. Risks and benefits of omega3 fats for mortality, cardiovascular disease and cancer: a systematic review. BMJ Online, 24 March 2006. 2. Hooper L, Thompson RL, Harrison RA, Summerbell CD, Moore H, Worthington HV, et al. Omega 3 fatty acids for prevention and treatment of cardiovascular disease. Cochrane Database Syst Rev. 2004; 18:CD003177. 3. Cleland LG, James MJ, Proudman SM. Fish oil: what the prescriber needs to know. Arthritis Res Ther. 2005; 8:202. 4. Lau CS, Morley KD, Belch JJF. Effects of fish oil supplementation on non-steroidal anti-inflammatory drug requirement in patients with mild rheumatoid arthritis-a double blind placebo controlled study. Br J Rheum. 1993; 32:982-989. 5. Bombardier C, Laine L, Reicin A, Shapiro D, Burgos-Vargas R, Davis B, Day R, et al. Comparison of upper gastrointestinal toxicity of rofecoxib and naproxen in patients with rheumatoid arthritis. VIGOR Study Group. N Engl J Med. 2000 23;343:1520-8.
Results presented as mean ±SD. Reference levels for urinary mercury are <75 nmol/24h and whole blood mercury are <70nmol/L. *assumes 0 if below limit of detection, † assumes limit of detection value if below limit. Competing interests: None declared |
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David E. Brown, Carpenter 1925 Belmar Dr., Kalispell, Montana 59901
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Testing individual nutrients, such as omega-3 fatty acids, for their protective benefit against heart disease is like testing the water holding capacity of defective buckets. No matter the size, shape, or what they're made from; if all have large holes in the bottom, none will be of much use for storing or transporting water. Likewise, adding one nutrient or another to a defective diet, a diet with multiple nutrient deficits and imbalances, is not likely to yield significant benefit, especially over the short term. In general, heart disease is a nutrient deficiency problem. While it's easy to obtain adequate calories these days, it's also easy to consume energy in configurations that preclude supportive nutrients. We call it junk food and we eat a lot of it. For upwards of four decades researchers have believed that reducing one's intake of dietary saturated fat and cholesterol would promote heart health. Consumers were advised to switch from animal fats to vegetable oils because of the latter's cholesterol lowering effects. With this endorsement, vegetable oil production went into high gear and "heart healthy" products proliferated to the point where omega-6 fatty acids became overly abundent in the food supply. So now we have a situation where consumers are ingesting about 25 times more omega-6 fats as omega-3 and researchers think that adding a few helpings of fish or supplementing with fish oil caspules is going to make a difference? Hardly. The remainder of the diet needs to be corrected before the beneficial effects of omega-3 fats can fully manifest themselves. This means replacing empty carbohydrate and vegetable oil calories with the vitamin/mineral rich foods that can supply the elements required for energy release, body building, and tissue repair. For a clear, plausible explanation as to what causes heart disease, I suggest pages 81-83 (and corresponding reference notes) of "Nutrition Against Disease" by Roger J. Willaims, PhD. David Brown e-mail davebnep@yahoo.com Competing interests: None declared |
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carron s scrimgeour, emergency medicine chamonix france
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I follow the view entirely that the health of our hearts and arteries should be balanced against the health of our planet. Prescribing asthma treatment that crosses Europe in polluting lorries -hence causing asthma- is just another example of how we are doing things wrong! Ecomedicine on the rise.. Competing interests: None declared |
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Eddie Vos, maintains health-heart.org Sutton (Qc) Canada J0E 2K0
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With all respect to the Robertsons, they repeat the urban myth that farmed fish may have little or no [sic] omega-3. This is is simply not true: they have roughly the same as wild fish since one cannot raise fish [or humans] only on plant based fats that ALL lack the relevant long-chain omega-3's, i.e. EPA [C20:5n-3] and DHA [C22:6n-3]. Another urban myth is the lack of purity or even toxicity of commercial fish oil, an idea soundly debunked by respondents G. E. Caughey et al: dioxins and the like are essentially below detection and at 1 gram/day oil intake one might get 2 mcg of mercury per YEAR, a mere whiff of one's dental association approved amalgam. Clearly, the danger is NOT getting sufficient fish-based omega-3's, not the nanograms of contaminants creating mega fear. Moreover, fish oil is the only sustainable source. vos{at}health-heart.org member ISSFAL Competing interests: None declared |
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Anna C Goodman, MSc Student of Epidemiology SE21 7EA
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I was delighted to read a discussion of omega 3 fatty acids which links the public health arguments in with the ecological issues – as Dr. Brunner points out, massive overfishing in the past half century has rendered our supply of omega 3 acids from wild fish stocks unsustainable. I was surprised, however, that there was no consideration of whether these could be substitued by omega 3 acids from other sources. I’m particularly thinking of the ‘good oil’ omega blends made from seeds which you can buy from health shops. Is there any evidence that consuming comparable amounts of the essential fatty acids from these oils is equivalent, from a health point of view, to getting omega 3 fat from fish? It seems to me a very important question as, if these seed-based oils could substitue oily fish, it would avoid both the problems of overfishing and of contamination with substances like mercury. Competing interests: None declared |
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John Balbus, MD, MPH, Health Program Director Environmental Defense, 1875 Connecticut Ave. NW - Suite 600, Washington DC 20009, USA, Timothy Fitzgerald, Scientist
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A recent editorial highlighted the paradox between the growing popularity of long chain omega-3 fatty acids and a globally dwindling fish supply.[1] Breaking downward cycles in fisheries requires altering the short- term economic incentives that stem from current management systems, which push fishermen to maximize today's catch at the expense of future populations and ecosystem health. Luckily, the oceans are resilient and inherently capable of providing far more fish than they currently do. For example, a single 24-inch female red snapper produces nine million eggs annually, while it would take more than 200 16-inch snappers to equal that feat.[2] Allowing these fish a few extra years to grow would yield a 200-fold increase in reproduction. Unfortunately, present fisheries policies allow the taking of too many fish too fast, often without leaving enough large, highly reproductive females. Well-designed science-based policies, such as those that allocate shares of annual catches directly to fishermen, can help correct this problem by aligning fishermen's economic interests with long-term ecosystem health. Absent such policies, more fish stocks will crash, leading to a negative-feedback cycle in which a dwindling number of populations will be increasingly exploited. Health professionals interested in encouraging the consumption of heart-healthy seafood have a vested interest in supporting sustainable fisheries policies – policies that will make seafood abundant and affordable not just next year, but also for years to come. Numerous opportunities exist, ranging from direct communications with patients about choosing ocean-friendly seafood, to encouraging decision makers to consider the long-term viability of fish stocks in setting national and international policy. As recently noted by McMichael and Butler, "Eating fish may be good for health, but eating too many fish too fast is bad for the biosphere's health, and therefore, in due course, for people."[3] With physicians' help, policies can be adopted that are good for both people and the biosphere – and thus for generations of people yet to come. 1. Brunner E. Oily fish and omega 3 fat supplements: Health recommendations conflict with concerns about dwindling supply. BMJ. 2006 Apr 1;332(7544):739-40. 2. Pauly D, Christensen V, Guénette S, Pitcher TJ, Sumaila UR, Walters CJ, et al. Towards sustainability in world fisheries. Nature. 2002;418:689-95. 3. McMichael A, Butler C. Fish, health and sustainability. Am J Prev Med. 2005 Nov;29(4):322-3. Competing interests: None declared |
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