The skinny on tuna fat: health implications

A novel strategy for triacylglycerides and polyhydroxyalkanoates production using waste lipids

Lipids are one of the main components of the organic matter present in the effluents of the food-processing industry. These waste streams can be biotransformed into valuable triacylglycerides (TAGs) and polyhydroxyalkanoates (PHAs), precursors of biofuels and biomaterials alternative to petroleum-based products. These compounds are yielded by mixed microbial cultures, and considering that both TAG and PHA accumulators may coexist within the community, it seems crucial to define those operational strategies that might control the selection of the dominant metabolic pathways (TAG or PHA accumulation). In this work, residual fish-canning oil was used as a carbon source in a two-stage process (culture selection and intracellular compounds accumulation) in which the substrate was simultaneously hydrolyzed in these two stages without the need for a previous fermentation unit. It was pretended to maximize preferential TAG or PHA storage in the accumulation reactor by the imposition of certain selective pressures in the enrichment one. Uncoupling C and N feedings and limiting nitrogen availability in the medium, allowed to maximize PHA production (82.3 wt% of PHAs, 0.80 Cmmol_PHA/Cmmol_S). Besides, when low pH in the famine phase was considered as additional selective pressure, it was possible to shift the ratio TAG:PHA from 4:96 obtaining 43.0 wt% of TAGs (0.67 Cmmol_TAG/Cmmol_S). Therefore, this novel and simplified process demonstrated versatility and efficiency in the storage of TAGs and PHAs from a unique residual feedstock and using an open culture proving that product selection can be harnessed if choosing the right operational conditions in the enrichment stage.

Abundance, composition, and potential intake of microplastics in canned fish

The existence of microplastics (MPs) in canned fish (tuna and mackerel) samples was investigated and their composition, possible sources and potential intake were assessed. Light and fluorescence microscopy were used for the quantification of potential MPs. Furthermore, micro-Raman microscopy, and scanning electron microscopy coupled with an energy dispersive X-ray were used to identify the polymer types and composition of MPs. The results showed that 80% of samples had at least one plastic particle and fibers were the most abundant shapes of MPs. Moreover, polyethylene terephthalate (32.8%) was the most common polymer type in canned fish samples. The fish, food additives, and contact materials during the cleaning and canning process are possible sources of MPs. Human intake estimation of MPs showed the possibility of plastics absorption by humans who consume canned fish several times/week. Hence, the results of this study showed the importance of MPs' guidelines for food safety and hygiene.

Comparison of Omega-3 Eicosapentaenoic Acid Versus Docosahexaenoic Acid-Rich Fish Oil Supplementation on Plasma Lipids and Lipoproteins in Normolipidemic Adults

Background: Eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) have both shared and different cardiovascular effects, and commonly used fish oil supplements have considerably varied EPA/DHA ratios. Aims: We compared the effects of fish oil supplements with different EPA/DHA ratios on lipoprotein metabolism. Methods: In a double-blind, randomized cross-over study, normolipidemic adults (n = 30) consumed 12 g/day of EPA-rich (EPA/DHA: 2.3) or DHA-rich (EPA/DHA: 0.3) fish oil for 8-weeks, separated by an 8-week washout period. Results: Both fish oil supplements similarly lowered plasma TG levels and TG-related NMR parameters versus baseline (p < 0.05). There were no changes in plasma cholesterol-related parameters due to either fish oil, although on-treatment levels for LDL particle number were slightly higher for DHA-rich oil compared with EPA-rich oil (p < 0.05). Both fish oil supplements similarly altered HDL subclass profile and proteome, and down regulated HDL proteins related to inflammation, with EPA-rich oil to a greater extent. Furthermore, EPA-rich oil increased apoM abundance versus DHA-rich oil (p < 0.05). Conclusions: Overall, fish oil supplements with varied EPA/DHA ratios had similar effects on total lipids/lipoproteins, but differences were observed in lipoprotein subfraction composition and distribution, which could impact on the use of EPA versus DHA for improving cardiovascular health.

Tuna Consumption, Mercury Exposure, and Knowledge about Mercury Exposure Risk from Tuna Consumption in University Students

We examined the relationships among tuna consumption, hair mercury levels, and knowledge of mercury exposure risk from tuna consumption in university students that were offered tuna daily at university-run dining halls. Hair total mercury levels in tuna consumers were higher than those in non-tuna consumers (average = 0.466 µg/g ± 0.328 standard deviation [SD], n = 20 vs 0.110 µg/g ± 0.105 SD, n = 33, respectively; p < 0.0001, Mann-Whitney U test), with tuna eaters exhibiting a positive relationship between self-reported tuna consumption at dining halls and hair mercury levels (R²  = 0.868, p < 0.0001, n = 17, linear regression). For all tuna eaters surveyed, more than half (54%) self-reported eating ≥3 tuna meals/wk, potentially exceeding the US Environmental Protection Agency's reference dose for methylmercury of 0.1 µg/kg body weight/d. Seven percent of study participants reported they consumed >20 tuna meals/wk, which was related to hair mercury levels >1 µg/g, a level of concern. Study participants had an overall lack of knowledge and confidence in their knowledge about mercury exposure risk from tuna consumption, with >99% of participants reporting low knowledge and low confidence in survey answers. Our study highlights the importance of education about the risks of tuna consumption, particularly in institutional settings where individuals have unlimited access to tuna products. Environ Toxicol Chem 2019;38:1988-1994. © 2019 SETAC.

Relation between dietary fat intake type and serum fatty acid status in children with cystic fibrosis

BACKGROUND AND OBJECTIVE

Children with cystic fibrosis (CF) and pancreatic insufficiency (PI) are at risk for fatty acid (FA) abnormalities and essential FA deficiency, with low linoleic acid (LA) and docosahexaenoic acid (DHA) concentrations and abnormal triene:tetraene (T:T) and arachidonic acid (AA):DHA ratios. The aim of the article was to determine whether type of dietary fat predicted serum LA, DHA, T:T, and AA:DHA ratios in subjects with CF and PI as compared to an unaffected comparison group.

METHODS

Serum FA concentrations were assessed by capillary gas-liquid chromatography (mol%) and dietary intake by 7-day weighed food records; the 3-day coefficient of fat absorption was calculated. Total energy intake was expressed in kilocalories.

RESULTS

A total of 65 subjects with CF and PI (8.4 ± 1.0 years, 32 girls) and 22 controls (8.5 ± 1.1 years, 13 girls) were included. Despite greater energy, saturated fat, and LA intake, the subjects with CF had lower serum LA and DHA and higher T:T and AA:DHA than those in the comparison group. Dietary total fat, monounsaturated fatty acid (MUFA), polyunsaturated fatty acid (PUFA), LA, total ω 6 polyunsaturated fatty acid (Tω6PUFA), and α-linolenic acid (ALA) intake positively predicted serum LA concentration. MUFA, total ω 3 polyunsaturated fatty acid (Tω3PUFA), and ALA intake positively predicted serum DHA concentration. Total dietary fat, MUFA, PUFA, Tω3PUFA, LA, and ALA intake negatively predicted serum T:T. ALA and Tω3PUFA intake negatively predicted serum AA:DHA.

CONCLUSIONS

Dietary fat patterns influenced serum LA, DHA, T:T, and AA:DHA in children with CF and PI. These data suggest that changes in dietary practices may result in FA profiles associated with improved clinical outcomes.