Tag Archives: cold-water fatty fish

Still Taking Fish Oil Supplements? Think Again

Salmon is one the the cold-water fatty fish loaded with omega-3 fatty acids

Salmon is one the the cold-water fatty fish loaded with omega-3 fatty acids

I’ve been sitting on this research report a few years, waiting until I had time to dig into it. That time never came. The full report is free online (thanks, British Medical Journal!). I scanned the full paper to learn that nearly all the studies in this meta-analysis used fish oil supplements, not the cold-water fatty fish the I recommend my patients eat twice a week. If you’re taking fish oil supplements on your doctor’s advice, don’t stop without consulting her.

Here’s the abstract:

Objective: To review systematically the evidence for an effect of long chain and shorter chain omega 3 fatty acids on total mortality, cardiovascular events, and cancer.

Data sources: Electronic databases searched to February 2002; authors contacted and bibliographies of randomised controlled trials (RCTs) checked to locate studies.

Review methods Review of RCTs of omega 3 intake for 3 6 months in adults (with or without risk factors for cardiovascular disease) with data on a relevant outcome. Cohort studies that estimated omega 3 intake and related this to clinical outcome during at least 6 months were also included. Application of inclusion criteria, data extraction, and quality assessments were performed independently in duplicate.

Results: Of 15 159 titles and abstracts assessed, 48 RCTs (36 913 participants) and 41 cohort studies were analysed. The trial results were inconsistent. The pooled estimate showed no strong evidence of reduced risk of total mortality (relative risk 0.87, 95% confidence interval 0.73 to 1.03) or combined cardiovascular events (0.95, 0.82 to 1.12) in participants taking additional omega 3 fats. The few studies at low risk of bias were more consistent, but they showed no effect of omega 3 on total mortality (0.98, 0.70 to 1.36) or cardiovascular events (1.09, 0.87 to 1.37). When data from the subgroup of studies of long chain omega 3 fats were analysed separately, total mortality (0.86, 0.70 to 1.04; 138 events) and cardiovascular events (0.93, 0.79 to 1.11) were not clearly reduced. Neither RCTs nor cohort studies suggested increased risk of cancer with a higher intake of omega 3 (trials: 1.07, 0.88 to 1.30; cohort studies: 1.02, 0.87 to 1.19), but clinically important harm could not be excluded.

Conclusion: Long chain and shorter chain omega 3 fats do not have a clear effect on total mortality, combined cardiovascular events, or cancer.

Steve Parker, M.D.

Reference: Hooper, Lee et al. Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review. BMJ  2006;332:752-760 (1 April), doi:10.1136/bmj.38755.366331.2F (published 24 March 2006).

Omega-3 Fatty Acid Supplements Fail to Stall Age-Related Brain Decline

I like fish, but cold whole dead fish leave me cold

Supplementation with omega-3 fatty acids does not help prevent age-related cognitive decline or dementia, according to an article at MedPage Today.

The respected Cochrane organization did a meta-analysis of three pertinent studies done in several countries (Holland, UK, and ?).

The investigators leave open the possibility that longer-term studies—over three years—may show some benefit.

I leave you with a quote from the MedPage Today article:

And while cognitive benefits were not demonstrated in this review, Sydenham and colleagues emphasized that consumption of two servings of fish each week, with one being an oily fish such as salmon or sardines, is widely recommended for overall health benefits.

Steve Parker, M.D.

Sydenham E, et al “Omega 3 fatty acid for the prevention of cognitive decline and dementia” Cochrane Database of Systematic Reviews 2012; DOI: 10.1002/14651858.CD005379.pub3.

Fish With Omega-3 Fatty Acids Reduce Risk of Blindness

Age-related macular degeneration is the leading cause of blindness in Americans over 65. Impaired vision precedes blindness. A recent study linked consumption of omega-3 fatty acids with 30% lower risk of developing macular degeneration. Believe me, it’s a lot better to prevent it than try to treat it once present.

(I have a couple older relatives with macular degeneration, so I pay close attention to the scientific literature.)

What’s the best source of omega-3 fatty acids? Our friend, the fish. Especially cold-water fatty fish such as tuna, trout, sardines, herring, mackerel, halibut, and sea bass. A few plants are also decent sources, but our bodies don’t utilize those omega-3 fatty acids as well as they do from fish.

Note that both the Advanced Mediterranean Diet and Ketogenic Mediterranean Diet feature fish.

Steve Parker, M.D.

Reference: SanGiovanni, J.P., et al. Long-chain polyunsaturated fatty acid intake and 12-y incidence of neovascular age-related macular degeneration and central geographic atrophy: AREDS report 30, a prospective cohort study from the Age-Related Eye Disease Study. American Journal of Clinical Nutrition, 90 (2009): 1,601-1,607. First published October 7, 2009. doi:10.3945/ajcn.2009.27594