Increasing dietary polyunsaturated fats and decreasing saturated fats is
associated with an increase in both overall death rates and heart disease death
rates
Use of dietary linoleic acid for secondary
prevention of coronary heart disease and death: evaluation of recovered data
from the Sydney Diet Heart Study and updated meta-analysis.
Ramsden CE, Zamora D, Leelarthaepin B, Majchrzak-Hong SF, Faurot KR, Suchindran CM, Ringel A, Davis JM, Hibbeln JR.
Source
Laboratory of Membrane Biophysics and
Biochemistry, National Institute on Alcohol Abuse and Alcoholism, National
Institutes of Health, Bethesda, MD 20892, USA. Chris.Ramsden@nih.gov
Erratum in
·
BMJ. 2013;346:f903.
Abstract
OBJECTIVE:
To evaluate the effectiveness of replacing dietary saturated fat with
omega 6 linoleic acid, for the secondary prevention of coronary heart disease
and death.
DESIGN:
Evaluation of recovered data from the Sydney Diet Heart Study, a single
blinded, parallel group, randomized controlled trial conducted in 1966-73; and
an updated meta-analysis including these previously missing data.
SETTING:
Ambulatory, coronary care clinic in Sydney, Australia.
PARTICIPANTS:
458 men aged 30-59 years with a recent coronary event.
INTERVENTIONS:
Replacement of dietary saturated fats (from animal fats, common
margarines, and shortenings) with omega 6 linoleic acid (from safflower oil and
safflower oil polyunsaturated margarine). Controls received no specific dietary
instruction or study foods. All non-dietary aspects were designed to be
equivalent in both groups.
OUTCOME MEASURES:
All cause mortality (primary outcome), cardiovascular mortality, and
mortality from coronary heart disease (secondary outcomes). We used an
intention to treat, survival analysis approach to compare mortality outcomes by
group.
RESULTS:
The intervention group (n=221) had higher rates of death than controls
(n=237) (all cause 17.6% v 11.8%, hazard ratio 1.62 (95% confidence interval
1.00 to 2.64), P=0.05; cardiovascular disease 17.2% v 11.0%, 1.70 (1.03 to
2.80), P=0.04; coronary heart disease 16.3% v 10.1%, 1.74 (1.04 to 2.92),
P=0.04). Inclusion of these recovered data in an updated meta-analysis of linoleic
acid intervention trials showed non-significant trends toward increased risks
of death from coronary heart disease (hazard ratio 1.33 (0.99 to 1.79); P=0.06)
and cardiovascular disease (1.27 (0.98 to 1.65); P=0.07).
CONCLUSIONS:
Advice to substitute polyunsaturated fats for saturated fats is a key
component of worldwide dietary guidelines for coronary heart disease risk
reduction. However, clinical benefits of the most abundant polyunsaturated
fatty acid, omega 6 linoleic acid, have not been established. In this cohort,
substituting dietary linoleic acid in place of saturated fats increased the
rates of death from all causes, coronary heart disease, and cardiovascular
disease. An updated meta-analysis of linoleic acid intervention trials showed
no evidence of cardiovascular benefit. These findings could have important
implications for worldwide dietary advice to substitute omega 6 linoleic acid,
or polyunsaturated fats in general, for saturated fats.
TRIAL REGISTRATION:
Clinical trials NCT01621087.
