A randomised trial of the effect of omega-3 polyunsaturated fatty acid supplements on the human intestinal microbiota

Objective; Omega-3 polyunsaturated fatty acids (PUFAs) have anticolorectal cancer (CRC) activity. The intestinal microbiota has been implicated in colorectal carcinogenesis. Dietary omega-3 PUFAs alter the mouse intestinal microbiome compatible with antineoplastic activity. Therefore, we investigated the effect of omega-3 PUFA supplements on the faecal microbiome in middle-aged, healthy volunteers (n=22). Design A randomised, open-label, cross-over trial of 8 weeks’ treatment with 4 g mixed eicosapentaenoic acid/docosahexaenoic acid in two formulations (soft-gel capsules and Smartfish drinks), separated by a 12-week ‘washout’ period. Faecal samples were collected at five time-points for microbiome analysis by 16S ribosomal RNA PCR and Illumina MiSeq sequencing. Red blood cell (RBC) fatty acid analysis was performed by liquid chromatography tandem mass spectrometry. Results; Both omega-3 PUFA formulations induced similar changes in RBC fatty acid content, except that drinks were associated with a larger, and more prolonged, decrease in omega-6 PUFA arachidonic acid than the capsule intervention (p=0.02). There were no significant changes in α or β diversity, or phyla composition, associated with omega-3 PUFA supplementation. However, a reversible increased abundance of several genera, including Bifidobacterium, Roseburia and Lactobacillus was observed with one or both omega-3 PUFA interventions. Microbiome changes did not correlate with RBC omega-3 PUFA incorporation or development of omega-3 PUFA-induced diarrhoea. There were no treatment order effects. Conclusion; Omega-3 PUFA supplementation induces a reversible increase in several short-chain fatty acid-producing bacteria, independently of the method of administration. There is no simple relationship between the intestinal microbiome and systemic omega-3 PUFA exposure. Trial registration number; ISRCTN18662143

Dietary intake of 20 polyphenol subclasses in a cohort of UK women

Background: Establishing and linking the proposed health benefits of dietary polyphenols to their consumption requires measurement of polyphenol intake in appropriate samples and an understanding of factors that influence their intake in the general population. Methods: This study examined polyphenol intake estimated from 3- and 7-day food diaries in a sample of 246 UK women aged 18–50 years. Estimation of the intake of 20 polyphenol subclasses commonly present in foods consumed by the sample studied was done using Phenol-Explorer® and USDA polyphenol databases. Women were participants in the Leeds Women’s Wellbeing Study (LWW) (n = 143), a dietary intervention study aimed at overweight women (mean age 37.2 ± 9.4 years; mean BMI 30.8 ± 3.1 kg/m2), and the Diet and Health Study (DH) (n = 103) which aimed to examine the relationship between polyphenol intake and cognitive function (mean age 25.0 ± 9.0 years; mean BMI 24.5 ± 4.6 kg/m2). Results: The estimated intake of polyphenol subclasses was significantly different between the two samples (p < 0.01) with consumption of 1292 ± 844 and 808 ± 680 mg/day for the LWW and DH groups, respectively. Flavanols and hydroxycinnamic acids were the most important contributors to the polyphenols consumed by both groups, owing to tea and coffee consumption. Other major polyphenol food sources included fruits, vegetables and processed foods. Conclusion: Older women consumed more polyphenol-containing foods and beverages, which was due to the higher coffee and tea consumption amongst the LWW participants