Rethinking Fish-Oil Pills
for Heart and Brain
New reports fail to prove benefits from omega-3 supplements.
Two recent reports may cause you to
have second thoughts about buying
that bottle of fish-oil pills. Both
published disappointing conclusions—
one finding no difference between
omega-3 supplements and placebo
against cardiovascular disease, the other
similarly negative for cognitive benefits.
Unlike many of the previous studies
linking fish-oil supplements to heart and
brain benefits, these new reports were
based on randomized clinical trials.
“There are strong data to indicate
that people who consume fish are at
lower risk of cardiovascular disease
than people who do not consume fish,”
says Alice H. Lichtenstein, DSc, director
of Tufts’ HNRCA Cardiovascular Nutrition
Laboratory. “This most recent
trial indicates that merely adding fish
oil to the diet, without changing other
components, does not improve cardiovascular
The ORIGIN study, a large, randomized
clinical trial, compared fish-oil
pills with a placebo over more than six
years in a range of outcomes primarily
related to heart disease. Researchers
tested 1,000 milligrams daily of the
omega-3s DHA and EPA against a placebo
in 12,536 patients with diabetes or
prediabetes, average age 64.
Reporting their findings in the New
England Journal of Medicine, Jackie
Bosch, MSc, from McMaster University,
and colleagues said that 9.1% of those in
the omega-3 group died of cardiovascular
causes, compared to 9.3% randomly
assigned to placebo. Differences were
similarly insignificant for all-cause mortality
(15.1% versus 15.4%) and major
vascular events (16.5% versus 16.3%).
Indeed, on almost every outcome measure,
there was little difference between
those on the omega-3 supplements and
those in the control group, including
stroke, heart attack, death from arrhythmia,
and heart-failure hospitalization.
Other indicators, such as blood pressure
and cholesterol levels, were also similar
except for triglycerides, which were significantly
lower in the fish-oil group.
Some previous trials have found a
benefit from omega-3 supplementation.
In 2000, the US Food and Drug Administration
(FDA) approved a qualified health
claim allowing EPA and DHA dietary
supplements to boast of heart benefits.
After a second review of the evidence, the
FDA expanded that claim in 2004 to also
cover foods high in EPA and DHA.
Bosch and colleagues speculated
that the lack of an apparent benefit
in their study could be because many
patients were taking heart-protective
medications, which could have masked
any omega-3 effects.
Just days after the disappointing
cardiovascular findings, a new review
of the evidence for a protective
benefit from omega-3s against mental
decline reported no significant difference
between fish-oil supplements and
placebo. The analysis, for the prestigious
Cochrane Review, looked at three
high-quality clinical trials totaling 3,536 participants.
Some previous observational studies have suggested that omega-3s might protect against cognitive decline, and that possibility makes sense, since fatty acids play an important role in brain health. DHA is the most prominent fatty acid in the brain, especially in the neurons and synapses of the cerebral cortex—the “gray matter” responsible for memory, language and thinking.
But the new Cochrane Review, which looked instead at omega-3 supplementation
in clinical trials, saw only tiny, statistically insignificant differences in performance on tests of memory, executive
function and mental processing speed. One trial also used a test called the mini-mental status examination (MMSE), in which participants given omega-3s scored only 0.07 points apart from those on placebo. The trials used dosages of the omega-3s found in fish oil ranging from 400 to 700 milligrams and lasted from 6 to 40 months.
Lead author Emma Sydenham, MSc, of the London School of Hygiene and Tropical Medicine, says, “It’s important to understand the difference between observational research and randomized controlled trials. In observational
studies, it’s really not possible to show cause and effect. It could be that people who eat fish or take fish-oil pills also have healthier lifestyles.”
Sydenham and colleagues could not find any randomized controlled trials of fish consumption and cognitive decline that met their standard of at least six months’ duration.
“Consumers should not be fooled into thinking that omega-3s necessarily improve cognitive health,” Sydenham adds. “It’s not a magic bullet.”
As for cardiovascular health, your best bet is to follow the recommendations
of the American Heart Association
and the latest Dietary Guidelines for Americans. Both advise consuming a variety of fish, preferably oily fish (such as salmon, tuna, mackerel, herring and trout), at least twice a week. Prepare fish by broiling, grilling or baking, not frying, and avoid breading and buttery sauces. Besides providing omega-3s, eating
at least two weekly meals featuring fish replaces less-healthy entrées that may be high in saturated fat.
Says Tufts’ Lichtenstein, “The important point to focus on is it’s the whole diet and not just one component that can be put in a pill. I think current guidance to consume at least two fish meals per week, with the exception of battered and fried fish fillets, is still the best advice we can give people.”
TO LEARN MORE: New England Journal of Medicine,
dx.doi.org/10.1056/NEJMoa1203859. Cochrane Database of Systematic Reviews dx.doi.org/10.1002/14651858.CD005379.pub3, www.cochranejournalclub.com/omega3-for-prevention-of-dementia-clinical.