DOI: 10.1017/S0007114524000138


1. Omega-3 PUFA dietary intake
2. Fish oil supplements study
3. UK Biobank omega-3 research
4. Benefits of oily fish consumption
5. Plasma omega-3 levels and health

In the recent publication of ‘The British Journal of Nutrition’, researchers have uncovered significant data on the relationship between the consumption of oily fish, the use of fish oil supplements (FOS), and plasma omega-3 polyunsaturated fatty acid (PUFA) levels in a sizeable cohort of the UK Biobank participants. This groundbreaking study sheds new light on how dietary habits and supplement use are interlinked and how these factors can modify the critical biomarkers of health related to omega-3 fatty acids.

The study, titled “Fish oil supplement use modifies the relationship between dietary oily fish intake and plasma omega-3 polyunsaturated fatty acid levels: An analysis of the UK Biobank,” involved an extensive analysis of 121,650 participants, providing robust observational evidence that has previously been lacking in the field of nutritional science. The use of NMR spectroscopy to measure plasma omega-3 PUFA levels was a pivotal move that allowed for a high degree of accuracy in the findings presented by the research team led by Joanna J Aldoori from the University of Leeds and Leeds Institute of Medical Research.

The comprehensive research utilised ordinal logistic regression models, which were finely adjusted for clinical and lifestyle factors, to quantify the contribution of two primary variables: the intake of dietary oily fish and the use of fish oil supplements. This approach enabled the team to tease apart the individual and combined effects of these variables on omega-3 PUFA levels.

According to the study’s results, oily fish intake and FOS use were reported by 38% and 31% of participants, respectively. The data revealed a clear trend; increasing oily fish intake aligned with a higher likelihood of concurrent FOS use (P<0.001). Participants who consumed oily fish at least twice a week boasted the strongest predictor of high total omega-3 PUFA levels, exhibiting an odds ratio (OR) of 6.7 (95% confidence interval [CI] 6.3-7.1) and similarly high levels of docosahexaenoic acid (DHA) with an OR of 6.6 (CI 6.3-7.1).

On the other hand, the independent predictor value of FOS use was comparable to eating oily fish less than once a week, with a similar OR for high plasma omega-3 PUFA levels (OR 2.0 [CI 2.0-2.1]) and for the low frequency fish consumption (OR 1.9 [CI 1.8-2.0]). A key observation from the study was that FOS use could lead to plasma omega-3 PUFA levels akin to those seen in individuals who fell into the next highest category of oily fish intake, thus potentially modifying the benefits otherwise attributed solely to dietary fish consumption.

The implications of these findings are significant and multidimensional. First, the study emphasizes that FOS use is notably more prevalent among individuals who regularly include oily fish in their diet. This pattern could suggest that health-conscious behaviors are typically clustered, with people who are attentive to their diet also being proactive in supplementing it. However, it also raises awareness about the need to account for FOS use when conducting research into dietary omega-3 PUFA intake and its correlations with health outcomes.

If researchers overlook the effect of fish oil supplements, there is a possibility of confounding results that might misrepresent the actual contribution of dietary fish to omega-3 PUFA levels. This could lead to overestimating the impact of fish consumption on plasma omega-3 concentrations and related health outcomes, such as cardiovascular health, cognitive function, and inflammation reduction.

The work of Aldoori and colleagues, thus, provides a precedent for future research, suggesting that any study examining the relationship between diet, blood biomarkers, and health should include a comprehensive assessment of both dietary intake and supplement use to obtain an accurate representation of the effects under investigation.


1. Aldoori, J. J., Zulyniak, M. A., Toogood, G. J., & Hull, M. A. (2024). Fish oil supplement use modifies the relationship between dietary oily fish intake and plasma omega-3 polyunsaturated fatty acid levels: An analysis of the UK Biobank. The British Journal of Nutrition, 1-27. doi:10.1017/S0007114524000138

2. Harris, W. S. (2017). Omega-3 fatty acids and cardiovascular disease: A case for omega-3 index as a new risk factor. Pharmacological Research, 119, 94-101. doi:10.1016/j.phrs.2017.01.021

3. Calder, P. C. (2015). Marine omega-3 polyunsaturated fatty acids and inflammatory processes: Effects, mechanisms and clinical relevance. Biochimica et Biophysica Acta (BBA) – Molecular and Cell Biology of Lipids, 1851(4), 469-484. doi:10.1016/j.bbalip.2014.08.010

4. Mozaffarian, D., & Wu, J. H. (2011). Omega-3 fatty acids and cardiovascular disease: Effects on risk factors, molecular pathways, and clinical events. Journal of the American College of Cardiology, 58(20), 2047-2067. doi:10.1016/j.jacc.2011.06.063

5. Swanson, D., Block, R., & Mousa, S. A. (2012). Omega-3 fatty acids EPA and DHA: Health benefits throughout life. Advances in Nutrition, 3(1), 1-7. doi:10.3945/an.111.000893

The new study marks an essential contribution to the intricate puzzle of how diet and supplemental nutrition influence human health. It provides a platform for future research to build upon, ensuring that scientific investigations into omega-3 fatty acids and their effects on health are as accurate and reliable as possible. Moreover, the study fosters a dialogue between consumers, clinicians, and researchers about the importance of considering all sources of nutrition when discussing the potential benefits and recommendations around omega-3 PUFA consumption.