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The effect of different sources of fish and camelina sativa oil on immune cell and adipose tissue mRNA expression in subjects with abnormal fasting glucose metabolism: a randomized controlled trial.
de Mello, VD, Dahlman, I, Lankinen, M, Kurl, S, Pitkänen, L, Laaksonen, DE, Schwab, US, Erkkilä, AT
Nutrition & diabetes. 2019;9(1):1
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Dietary fish oils, particularly omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) found in oily fish, nuts and seeds have long been researched and purported to have both anti-inflammatory and glucose-stabilising effects when consumed orally and it is widely believed that in reducing low-grade inflammation and stabilising blood glucose levels, the risk of suffering from type 2 diabetes, heart disease or a stroke is reduced. Lean fish on the other hand has been far less researched with regards to its protective effects. This study was a randomised controlled study designed to assess and compare the protective effects of fish oils and Camelina Sativa oil (CSO - a seed oil containing alpha-linolenic acid) on inflammatory-related genes in subjects with suggestive pre-diabetes. Subjects were allocated to a randomised group and instructed to consume a given amount of either fatty fish, lean fish, camelina oil, or no fish/oil (control group). The study was carried out on 72 participants over a 12-week period. Although no significant change could be seen on inflammatory gene expression for the group consuming fatty fish, there was a modest decrease in inflammatory gene markers in the group consuming lean fish and a significant decrease in the group consuming CSO. Implications from this study suggest that CSO exerts its protective effect by reducing inflammation, therefore possibly decreasing the risk of strokes and cardiovascular episodes. The authors suggest that consuming a variety of fish, especially lean fish 4 times/ week could also play a protective role in cardiovascular health and type 2 diabetes.
Abstract
BACKGROUND/OBJECTIVES Molecular mechanisms linking fish and vegetable oil intakes to their healthy metabolic effects may involve attenuation of inflammation. Our primary aim was to examine in a randomized controlled setting whether diets enriched in fatty fish (FF), lean fish (LF) or ALA-rich camelina sativa oil (CSO) differ in their effects on the mRNA expression response of selected inflammation-related genes in peripheral blood mononuclear cells (PBMCs) and subcutaneous adipose tissue (SAT) in subjects with impaired fasting glucose. SUBJECTS/METHODS Samples from 72 participants randomized to one of the following 12-week intervention groups, FF (n = 19), LF (n = 19), CSO (n = 17) or a control group (n = 17), were available for the PBMC study. For SAT, 39 samples (n = 8, n = 10, n = 9, n = 12, respectively) were available. The mRNA expression was measured at baseline and 12 weeks by TaqMan® Low Density Array. RESULTS In PBMCs, LF decreased ICAM1 mRNA expression (P < 0.05), which was different (P = 0.06, Bonferroni correction) from the observed increase in the FF group (P < 0.05). Also, compared to the control group, LF decreased ICAM1 mRNA expression (P < 0.05). Moreover, the change in ICAM1 mRNA expression correlated positively with the intake of FF (P < 0.05) and negatively with the intake of LF (P < 0.05), independently of study group. A diet enriched in CSO, a rich source of alpha-linolenic acid (ALA), decreased PBMC IFNG mRNA expression (P < 0.01). The intake of CSO in the CSO group, but not the increase in plasma ALA proportions, correlated inversely with the IFNG mRNA expression in PBMCs (P = 0.08). In SAT, when compared with the control group, the effect of FF on decreasing IL1RN mRNA expression was significant (P < 0.03). CONCLUSION We propose that CSO intake may partly exert its benefits through immuno-inflammatory molecular regulation in PBMCs, while modulation of ICAM1 expression, an endothelial/vascular-related gene, may be more dependent on the type of fish consumed.
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Fish consumption and markers of colorectal cancer risk: a multicenter randomized controlled trial.
Pot, GK, Majsak-Newman, G, Geelen, A, Harvey, LJ, Nagengast, FM, Witteman, BJ, van de Meeberg, PC, Timmer, R, Tan, A, Wahab, PJ, et al
The American journal of clinical nutrition. 2009;90(2):354-61
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Colorectal cancer (CC) risk is strongly related to dietary habits, with 65–75% of the incidence of CC attributed to dietary factors. This RCT studied the effects of fish consumption on markers of CC risk. 242 patients, either at high risk of developing CC or with a healthy bowel, were randomly assigned to 3 groups - 2 portions of oily fish per week, 2 portions of lean fish per week, or a control group who received dietary advice only for 6 months. 216 patients completed the trail. No statistically significant effect on CC risk markers was found between the fish groups and controls at 6 months. These results did not support the hypothesis that additional fish consumption over a 6-month period changes the number of colonic precancerous cells. The authors call for further studies to include non-fish eaters to further test their hypothesis.
Abstract
BACKGROUND Diet is a major factor in the etiology of colorectal cancer, with high fish consumption possibly decreasing colorectal cancer risk, as was shown in several observational studies. To date, no intervention trials have examined the possible beneficial effects of fish intake on colorectal cancer risk. OBJECTIVE The objective was to investigate the effects of a 6-mo intervention with oil-rich or lean fish on apoptosis and mitosis within the colonic crypt. DESIGN In a multicenter, randomized, controlled intervention trial, patients with colorectal polyps, inactive ulcerative colitis, or no macroscopic signs of disease were recruited (n = 242) and randomly allocated to receive dietary advice plus either 300 g oil-rich fish (salmon) per week (n = 82), 300 g lean fish (cod) per week (n = 78), or only dietary advice (DA) (n = 82). Apoptosis and mitosis were measured in colonic biopsy samples collected before and after intervention (n = 213). RESULTS The total number of apoptotic cells per crypt did not increase in the salmon or cod group: -0.10 (95% CI: -0.36, 0.16) and -0.06 (95% CI: -0.32, 0.20), respectively, compared with the DA group. The total number of mitotic cells per crypt decreased nonsignificantly in the salmon group (-0.87; 95% CI: -2.41, 0.68) and in the cod group (-1.04; 95% CI: -2.62, 0.53) compared with the DA group. Furthermore, the distribution of mitosis within the crypt did not significantly change in either group. CONCLUSION An increase in the consumption of either oil-rich or lean fish to 2 portions weekly over 6 mo does not markedly change apoptotic and mitotic rates in the colonic mucosa. This trial was registered at www.clinicaltrials.gov as NCT00145015.