Chowdhury et al, 2014, Ann Int Med

Association of Dietary, Circulating, and

Supplement Fatty Acids With

Coronary RiskA Systematic Review and Meta-analysis

Chowdhury et al, 2014, Ann Int Med

(Quick) paper summary• Aim: Associations between fatty acids and

coronary disease• Method: Meta-analysis of prospective trials

• Dietary FA intake• Biomarkers of plasma FAs• Intervention (supplementation) trials

• Results (later)• Conclusions: ”Evidence does not clearly

support CV guidelines that encourage high consumption of polyunsaturated FAs, and low consumption of total SFAs”

Media interpretation of the paper

Media dramatization of the paper

Scientist backlash?• Complaints• Controversy • Calls (for retraction):

Not universal…..

Resolution to the 3-way

Proposed resolution

1. Consider the history of the paper2. Read the results3. Consider the methodology

• What was done• What was not done

4. Consider the original studies5. Consider other research

1. History of the paper

2. Read the results• (now there is a novelty).

2. Read the results• Plasma SFAs

2. Read the results• Plasma MUFAs

2. Read the results• Plasma PUFAs (ω-3)(remember – EVERYTHING we knew about diet was wrong).

2. Read the results• Plasma PUFAs (ω-6)

2. Read the results• Intervention (supplementation) trials

2. Read the results• Self-reported habitual intake of total SFA

not associated with cardiac events• Self-reported habitual intake of total MUFA

not associated with cardiac events• Self-reported habitual intake of α-linolenic

not associated with cardiac events• Self-reported habitual intake of LC ω-3

protective• Self-reported habitual intake of Total ω -6

not associated with cardiac events• Total trans fat associated

2. Read the results• Plasma SFAs: only 17:0 protective. 14:0;

15:0, 16:0, 15:0, 18:0 not associated• Total MUFA not associated• All LC ω-3 strongly protective individually• No evidence that total LC ω -3 associated• Protective effect of ARA, no association

with other ω-6

2. Read the results• Intervention trials showed no effect of

supplementation for α-linolenic, total LC ω-6, or ω-6

My first conclusions• Different FAs have different associations

with outcomes• Those most associated with a protective

effect have not been measured in the diet, nor studied in interventions

• But, no evidence that total saturated fat (intake / plasma) associated with events

• Convincing evidence that some ω-3 protective, although this has not been studied in an intervention trial.

In defense of the authors:• … do not clearly support .. guidelines that

promote high consumption of ω-6 PUFA and … reduced consumption of SFA

• LC ω -3 PUFAs in primary prevention• odd-chain SFAs (…milk or dairy

consumption) may have less deleterious effects

3. Consider the methodology

The development of cardiac events

The development of cardiac events

3. Consider the methodlogy

3. Consider the methodology

• Nutrient density substitution models convey information on dietary substitution; associations do not.

4. Consider the original samples• Timeframe• Participants & baseline characteristics• Event rate was up to 42%

Acknowledgements• Dariush Mozaffarian*• Brian Steffen*• American Heart Association*

*The views expressed in this presentation are not necessarily the views of the organizations / individuals

Further discussion• Is this an irresponsible paper? • If so – who was irresponsible?• Should we reconsider guidelines on

saturated fat?• Do YOU know what the guidelines are?• What about other outcomes?• The role of carbohydrates