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Evidence Summary

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In people with, or at risk of, heart disease, fatty acid supplements do not prevent heart attacks or death

Chowdhury R, Warnakula S, Kunutsor S, et al. Association of dietary, circulating, and supplement fatty acids with coronary risk: a systematic review and meta-analysis. Ann Intern Med. 2014;160:398-406.

Review question

Do fatty acid supplements reduce risk of events related to heart disease, such as heart attacks or death?

Background

Fatty acids help our bodies grow and develop. They are also thought to improve our health, including reducing blood fats and risk of heart disease (e.g., coronary artery disease, angina, heart rhythm problems).

We get fatty acids, which include omega-3 and omega-6 polyunsaturated fatty acids and alpha-linolenic acid, from foods or supplements that contain fish, nut, flax seed or plant oils, such as sunflower oil, walnut oil and evening primrose oil.

How the review was done

The researchers did a systematic review, searching for studies that were published up to June 2013.

They found 27 randomized controlled trials with 105,085 people.

Most people had heart disease (e.g., coronary artery disease, angina, heart rhythm problems) or risk factors for heart disease (e.g., high blood pressure, diabetes, current smoker).

Treatments were omega-3 fatty acid supplements, including alpha-linolenic acid, and omega-6 fatty acid supplements.

Most treatments were compared with a placebo or other nut or plant oils, although some were compared with specific diets or dietary advice, or another treatment.

What the researchers found

Compared with placebo or other treatments, none of the fatty acid supplements reduced events related to heart disease, such as heart attack or death.

Conclusion

In people with, or at risk of, heart disease, use of fatty acid supplements does not reduce events related to heart disease, such as heart attacks or death.

Fatty acid supplements vs control* to reduce events related to heart disease (e.g., heart attack or death)

Type of fatty acid supplement

Number of trials (people)

Rate of events with supplement

Rate of events with control

Absolute effect of fatty acid supplements†

Omega-3 (alpha-linolenic acid)

4 trials (18,866 people)

2.2%

2.3%

No difference in effect

Omega-3 (other than alpha-linolenic acid)

17 trials (76,580 people)

6.3%

6.7%

No difference in effect

Omega-6

8 trials (14,476 people)

6.1%

7.1%

No difference in effect

*Control included placebo, other nut or plant oils, specific diets or dietary advice, or other treatments.

†Although the rates for the 2 groups look a little different, the differences were not statistically significant. This means that the differences could simply be due to chance rather than due to the different treatments.




Glossary

Angina
Chest pain due to reduced blood flow to the heart.
Placebo
A harmless, inactive, and simulated treatment.
Randomized controlled trials
Studies where people are assigned to one of the treatments purely by chance.
Risk factors
Aspects making a condition more likely.
Systematic review
A comprehensive evaluation of the available research evidence on a particular topic.

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DISCLAIMER These summaries are provided for informational purposes only. They are not a substitute for advice from your own health care professional. The summaries may be reproduced for not-for-profit educational purposes only. Any other uses must be approved by the McMaster Optimal Aging Portal (info@mcmasteroptimalaging.org).

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