Listen to this PodcastMore 60-Second Science
-
The Best Science Writing Online 2012
Showcasing more than fifty of the most provocative, original, and significant online essays from 2011, The Best Science Writing Online 2012 will change the way...
Read More »
It’s been touted for its healthful, anti-inflammatory properties. It’s been recommended for helping ease the pain of arthritis, preventing cancer and slowing memory loss. But some recent studies of fish oil show that it may not always act as advertised—and that you can sometimes have too much of a good thing.
First, the latest news. Researchers spent 18 months following almost 300 patients with mild to moderate Alzheimer’s. Some took fish oil, others a placebo. And there was no difference cognitively between the two groups. The study is in the current Journal of the American Medical Association. [Joseph Quinn et al., "Docosahexaenoic Acid Supplementation and Cognitive Decline in Alzheimer Disease"]
It’s a mixed bag on cancer. A study of more than 35,000 postmenopausal women found that those who took fish oil seemed half as likely to develop breast cancer as those who didn’t. That work was in the July issue of Cancer Epidemiology, Biomarkers & Prevention. [Theodore Brasky et al., "Specialty Supplements and Breast Cancer Risk in the VITamins And Lifestyle (VITAL) Cohort"]
But a study in the October 15th issue of Cancer Research found that mice with inflamed bowels developed colitis and aggressive colon cancer when they were given high doses of fish oil. [Hillary Woodworth et al., "Dietary Fish Oil Alters T Lymphocyte Cell Populations and Exacerbates Disease in a Mouse Model of Inflammatory Colitis"]
So, fish oil might in fact have a healthful role in some circumstances. But you don’t want to swallow every fish story.
—Cynthia Graber
[The above text is an exact transcript of this podcast.]
See what we're tweeting about
8 Comments
Add CommentNow that was one of the biggest BS stories I ever heard of. Lining up 300 patients with dementia and putting half on placebo and half on active treatment is NOT objective testing when it comes to that disease. Poor scientific form. Piss poor.
Reply | Report Abuse | Link to thisThe only way to test that out with real results, is to have their OWN neurologist monitor them, and test them in a standardized method, comparing the degree of change against those in the control group. Every dementia patient degrades at a different rate and presents in a relatively unique fashion. This test had a very poor form.
I have to say I agree with Highlite. This is hardly a thorough examination of the possible effects of taking fish oil. The article, in general, was of interesting topic but with no real information. Is fish oil still good for your heart? How much was "high doses" of fish oil in mice? Does the mouse experiment mean we (men) should perhaps not be taking fish oil, or just a limited amount?
Reply | Report Abuse | Link to thisDo Japanese or Eskimo's drop dead on a regular basis. Short term studies on supplements that need decades to show changes is ludicrous. Sci Am has decided conclusively that climate change is due to CO2 and now has put dietary supplements on trial. Disclosure is proper for studies such as this and there is no reason not to think drug manufacturers aren't behind these studies. The problem with non medical reporters is they know just enough to be dangerous.
Reply | Report Abuse | Link to thisThis study was not intended to determine whether a diet high in fish or fish oil Omega-3 dietary supplements could reduce the risk of Alzheimer's onset, only to determine whether the one Omega-3 acid found in the brain could reduce the occurrence of dementia in Alzheimer patients. The researchers found that it did not.
Reply | Report Abuse | Link to thisThe study drug was actually an algal-derived DHA, one specific fatty acid, not a fish oil containing Omega-3 fatty acids.
The stated objective of this study:
"To determine if supplementation with DHA slows cognitive and functional decline in individuals with Alzheimer disease."
The JAMA report states:
"Docosahexaenoic acid (DHA) is an omega-3 fatty acid identified as a potential treatment for Alzheimer disease. Epidemiological studies have shown that omega-3 fatty acid consumption reduces Alzheimer disease risk and DHA modifies the expression of Alzheimer-like brain pathology in mouse models."
"Several studies have found that consumption of fish, the primary dietary source of omega-3 fatty acids, is associated with a reduced risk of cognitive decline or dementia.1-6 Some studies have found that consumption of DHA, but not other omega-3 fatty acids, is associated with a reduced risk of Alzheimer disease.3 Studies of plasma fatty acids have confirmed the dietary studies, finding that plasma levels of omega-3 fatty acids, and especially DHA, are associated with a reduced risk of Alzheimer disease.7-8 The most abundant long-chain polyunsaturated fatty acid in the brain, DHA is enriched in synaptic fractions and is reduced in the brains of patients with Alzheimer disease.9-10 The other major omega-3 fatty acid found in fish, eicosapentaenoic acid, is virtually absent from the brain."
I was prescribed a Omega-3 fatty acid medication to treat very high triglycerides in may, 2008. The reason I know that date is because, knowing nothing about Omega-3 benefits, within 2 weeks I noticed that my ability to reason had returned to levels I'd not known for nearly 10 years suffering from affects of heart disease, chemo, severe anemia, etc.
Reply | Report Abuse | Link to thisI found that I could not reach the prescribed 4G daily dose due to severe abdominal gas production, but I did stabilize on a dose of 2G of Lovaza along with another non-statin medication to reduce triglycerides, at my insistence.
Investigating later, I speculate that I'd suffered some damage to probably the the myelin sheaths insulating neurons that was repaired by the Omega-3 medication. I suspect that the restoration of cognitive abilities can only occur in some cases where damage has occurred, although some studies of children have indicated enhancements in memory test performance.
The effect was pronounced enough for me that it was noticed even though I had no expectation of any intellectual benefit. I have no way of knowing whether the same benefit could have been attained using Omega-3 dietary supplements, since their purity and dosage of specific fatty acids are unregulated.
I'm not convinced that 300 people is enough the make a study. The same with the amount of time they dedicated to the study.
Reply | Report Abuse | Link to thisBlaming SciAm for this article is like shooting the messenger.
Reply | Report Abuse | Link to thisIt provides more evidence that the picture with "natural" supplements is not going to be a clear one. It's reminiscent of the trials with beta-carotene, which produced a counter-intuitive scenario:
http://www.cancer.gov/clinicaltrials/results/summary/2004/final-caret1204
http://cancer.about.com/od/foodguide/f/cancerbetacaro.htm
http://en.wikipedia.org/wiki/Carotene
Whether a substance is useful or harmless, depends not just on the substance itself, but where and when and how it is applied. Should we be surprised that substances can be noxious in one context or helpful in another?
The human organism is such a complex system, why should we expect anything else?
I agree that you don't shoot the messenger, but the podcast reporter did get a few fundamental facts wrong. First, as one person noted, they did not test fish oil in the Alzheimer's study, they used algal DHA and did not test another omega-3 that is found in fish oil, EPA. Also, regardless of which source they tested, the patients had already been diagnosed with Alzheimer's so for a successful test it would have had to reverse the brain damage that had been done. The evidence on omega-3s has been primarily in preventing the damage before it occurs.
Reply | Report Abuse | Link to thisIn the mouse study, she said the mice had increased incidences of colitis, but actually the colitis was intentionally induced in the mice as part of the experimental design. The study looked at whether omega-3s could stop the development of colon cancer from colitis, so they had to give the mice colitis to test the hypothesis. Also, the doses they gave the mice were many multiples higher than a normal consumer takes. in fact, they were even higher than patients under the care of doctors take for pharmaceutical omega-3s.
As phalaris noted in their comment, the body is complex, the cause of these diseases is multi-factorial, and the prevention, progression and treatment of these diseases are distinct. So omega-3s may play a valuable role in these conditions, but a single study cannot be definitive because you are only testing a single primary variable. Certainly more research is yet to come.