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Meta-Analysis
. 2020 Apr;122(8):1260-1270.
doi: 10.1038/s41416-020-0761-6. Epub 2020 Feb 29.

Omega-3, omega-6 and total dietary polyunsaturated fat on cancer incidence: systematic review and meta-analysis of randomised trials

Sarah Hanson  1 , Gabrielle Thorpe  1 , Lauren Winstanley  2 , Asmaa S Abdelhamid  2 , Lee Hooper  3 ; PUFAH group
Collaborators, Affiliations
Meta-Analysis

Omega-3, omega-6 and total dietary polyunsaturated fat on cancer incidence: systematic review and meta-analysis of randomised trials

Sarah Hanson et al. Br J Cancer. 2020 Apr.

Abstract

Background: The relationship between long-chain omega-3 (LCn3), alpha-linolenic acid (ALA), omega-6 and total polyunsaturated fatty acid (PUFA) intakes and cancer risk is unclear.

Methods: We searched Medline, Embase, CENTRAL and trials registries for RCTs comparing higher with lower LCn3, ALA, omega-6 and/or total PUFA, that assessed cancers over ≥12 months. Random-effects meta-analyses, sensitivity analyses, subgrouping, risk of bias and GRADE were used.

Results: We included 47 RCTs (108,194 participants). Increasing LCn3 has little or no effect on cancer diagnosis (RR1.02, 95% CI 0.98-1.07), cancer death (RR0.97, 95% CI 0.90-1.06) or breast cancer diagnosis (RR1.03, 95% CI 0.89-1.20); increasing ALA has little or no effect on cancer death (all high/moderate-quality evidence). Increasing LCn3 (NNTH 334, RR1.10, 95% CI 0.97-1.24) and ALA (NNTH 334, RR1.30, 95% CI 0.72-2.32) may slightly increase prostate cancer risk; increasing total PUFA may slightly increase risk of cancer diagnosis (NNTH 125, RR1.19, 95% CI 0.99-1.42) and cancer death (NNTH 500, RR1.10, 95% CI 0.48-2.49) but total PUFA doses were very high in some trials.

Conclusions: The most extensive systematic review to assess the effects of increasing PUFAs on cancer risk found increasing total PUFA may very slightly increase cancer risk, offset by small protective effects on cardiovascular diseases.

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Conflict of interest statement

S.H., G.T., A.S.A. and L.H. had financial support via the University of East Anglia from the World Health Organization for the submitted work, and L.H. and A.A. were also funded to attend WHO meetings and present review results; no financial relationships with any organisations that might have an interest in the submitted work in the previous three years; no other relationships or activities that could appear to have influenced the submitted work.

Figures

Fig. 1
Fig. 1
Forest plot showing effects of increasing omega-3, omega-6 and total PUFA on any cancer diagnosis, using random-effects meta-analyses.
Fig. 2
Fig. 2
Forest plot showing effects of increasing omega-3, omega-6 and total PUFA on death from any cancer, using random-effects meta-analyses.
Fig. 3
Fig. 3
Forest plot showing effects of increasing omega-3, omega-6 and total PUFA on diagnosis of breast cancer in women participants, using random-effects meta-analyses.
Fig. 4
Fig. 4
Forest plot showing effects of increasing omega-3, omega-6 and total PUFA on diagnosis of prostate cancer in male participants, using random-effects meta-analyses.
Fig. 5
Fig. 5. Visual representation of number of additional diagnoses or deaths incurred or avoided per 1000 people increasing their LCn3, ALA or total PUFA intake across cancer and cardiovascular outcomes.
Bars above zero suggest the number of people who would benefit of 1000 people consuming more PUFA (LCn3, ALA or total PUFA), bars below zero suggest the number of people who would be harmed of 1000 people consuming more PUFA. Where the evidence suggests little or no effect zero appears, and where the evidence is of very low quality no data appear. Cancer data are from this review, CVD data from sister Cochrane reviews.,
See this image and copyright information in PMC

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