Plasma fatty acids: Biomarkers of dietary intake?

Changes in serum lipids following consumption of coconut oil and palm olein oil: A sequential feeding crossover clinical trial

BACKGROUND

High incidence of cardiovascular disease (CVD) in South Asia is linked to genetic predisposition and diets high in saturated fatty acids (SFAs). Increased CVD prevalence correlates with rising palm oil consumption in some South Asian countries, where coconut oil and palm olein oil are primary SFA sources.

OBJECTIVE

Compare the effects of coconut oil and palm olein oil on serum lipoprotein lipids and biochemical parameters in healthy adults.

METHODS

A sequential feeding crossover clinical trial with two feeding periods of 8 weeks each was conducted among 40 healthy adults. Participants were provided palm olein oil in the first feeding period followed by coconut oil with a 16-week washout period in between. The outcomes measured were the difference in serum low-density lipoprotein cholesterol (LDL-C), total cholesterol (TC) and high-density lipoprotein cholesterol (HDL-C), TC/HDL-C ratio, triglycerides (TG), very-low-density lipoprotein cholesterol (VLDL-C), fasting plasma glucose (FPG), and liver enzymes.

RESULTS

Thirty-seven participants completed the study. LDL-C decreased by 13.0 % with palm olein oil (p < 0.001) and increased by 5.6 % with coconut oil (p = 0.044), showing a significant difference (p < 0.001). TC decreased by 9.9 % with palm olein oil (p < 0.001) and increased by 4.0 % with coconut oil (p = 0.044).

CONCLUSION

Palm olein oil consumption resulted in more favorable changes in lipid-related CVD risk factors (TC, LDL-C, TC:HDL-C, and FPG) compared to coconut oil. Clinical Trial Registry number and website where it was obtained: (SLCTR/2019/034); https://slctr.lk/trials/slctr-2019-034.

The degree of food processing can influence serum fatty acid and lipid profiles in women with severe obesity

Background

The increase in the prevalence of obesity is associated with the increase in the consumption of ultra-processed foods and may be related to the increase in the disorders involving metabolism and the transport and storage of fatty acids.

Objective

To evaluate the effect of processed food consumption according to the degree of processing on the serum fatty acid levels and lipid profile of women with severe obesity.

Methods

This was a cross-sectional study. Data were collected from anthropometric assessments, the food frequency questionnaire (FFQ), and blood tests for lipidogram studies and serum fatty acid measurements. The foods consumed were identified through the FFQ and classified according to the degree of processing based on the NOVA rating, and the frequencies of consumption were transformed into scores, as proposed by Fornés methodology. Data were analyzed using IBM SPSS Statistics, version 21. The significance level for the analysis was set at 5%.

Results

This study included 44 women with a mean age of 40.59 years and mean body mass index of 48.61 kg/m2. An inverse association was observed between the consumption of unprocessed and the occurrence of hypertriglyceridemia (p = 0.021) and levels of triglycerides (p = 0.047), total cholesterol (p = 0.030), and very low-density lipoprotein-cholesterol (p = 0.039). The consumption of processed foods was positively associated with the presence of hypertriglyceridemia (p = 0.044) and omega 6/3 ratio (p = 0.001) and negatively associated with total omega 3 levels (p = 0.011). The consumption of processed foods was positively associated with total cholesterol (p = 0.041) and negatively associated with the omega 3/6 ratio (p = 0.001). A negative correlation was found between the average consumption of ultra-processed foods (at least once a week) and serum level of high-density lipoprotein (p = 0.035).

Conclusion

The consumption of processed and ultra-processed foods was associated with unfavorable lipid profiles and fatty acid levels in women with severe obesity. These results emphasize the importance of promoting the consumption of unprocessed food to mitigate metabolic disorders linked to processed food intake.

Association between fatty acids and the risk of impaired glucose tolerance and type 2 diabetes mellitus in American adults: NHANES 2005-2016

BACKGROUND

Fatty acids (FAs) play a major role in regulating insulin sensitivity. However, owing to dietary quantitative tools, it has been challenging to study the dietary FAs in previous studies. There is a lack of knowledge regarding the associations between dietary FAs and the risk of impaired glucose tolerance (IGT) and type 2 diabetes mellitus (T2DM).

METHODS

Dietary FAs, adjustment of variables including age, sex, race, educational level, poverty to income ratio, body mass index, smoking, hypertension, physical activity, and diabetes data were extracted from the National Health and Nutrition Examination Survey 2005-2016. A multivariate logistic regression model was used to determine the associations between FA intake and the risk of IGT and T2DM.

RESULTS

This serial cross-sectional study included 9082 samples. After adjusting all the variables, a negative correlation was observed between total saturated FA and the risk of IGT (OR = 0.991, 95% (CI): 0.985-0.998, P = 0.024). Total FA at quintile 4 was negatively correlated with T2DM (OR = 0.714, 95% CI: 0.532-0.959, P = 0.025) compared with quintile 1. Factor analysis identified four factors of which F4 was negatively associated with the risk of T2DM (OR = 0.824, 95% CI: 0.715-0.949, P = 0.029). Based on this factor, we identified an unsaturated FA signature (n = 4 FAs, including octadecenoic acid (18:1), octadecadienoic acid (18:2), octadecatrienoic acid (18:3), and eicosenoic acid (20:1)).

CONCLUSIONS

Several unsaturated FAs with high proportions in natural oils may reduce the risk of T2DM.

Relevance of ω-6 GLA Added to ω-3 PUFAs Supplements for ADHD: A Narrative Review

The use of polyunsaturated fatty acids in Attention-Deficit/Hyperactivity Disorder (ADHD) and developmental disorders has been gaining interest with preparations containing different dosages and combinations. Gamma-linolenic acid (GLA) is an ω-6 fatty acid of emerging interest with potential roles as an adjuvant anti-inflammatory agent that could be used with ω-3 PUFAs in the treatment of ADHD and associated symptoms. A narrative review was undertaken to examine the potential role(s) of the ω-6 fatty acid GLA. PubMed, Google Scholar, and Scopus were searched to examine the potential role(s) of the ω-6 fatty acid GLA as (1) an antioxidant and anti-inflammatory agent, (2) a synergistic nutrient when combined with ω-3 PUFAs, and (3) a potential etiological factor in ADHD and its treatment. The results show that GLA exerts anti-inflammatory effects by increasing dihomo-gamma-linolenic acid in immune cells. ω-3 PUFAs, such as EPA and DHA, are often co-administered with GLA because these ω-3 PUFAs may prevent the accumulation of serum arachidonic acid in response to GLA administration without limiting the storage of DGLA in immune cells. The administration of ω-3 PUFAs alone might not be sufficient to effectively treat patients with ADHD and developmental disorders. Overall studies point towards a combination of EPA and DHA with GLA in a 9:3:1 ratio appearing to be associated with ADHD symptom improvement. A combination of PUFAs may lead to better outcomes.

Changes in fatty acid levels (saturated, monounsaturated and polyunsaturated) during pregnancy

BACKGROUND

During pregnancy a high amount of fatty acids (FA) is necessary to meet foetus demands, which vary during gestation. The present study describes the changes in maternal fatty acid concentrations during pregnancy in a sample of pregnant women.

METHODS

This is a longitudinal study of 479 pregnant women who were monitored from the first trimester to third trimester of pregnancy. Data on maternal characteristics were recorded and a serum sample was collected in each trimester. The fatty acid profile (saturated (SFA: total, lauric acid, myristic acid, palmitic acid, stearic acid), monounsaturated (MUFA: total, palmitoleic acid, oleic acid) and polyunsaturated fatty acids (PUFA: total omega-6 (n-6), linoleic acid, dihomo-γ-linolenic acid, arachidonic acid (AA), total omega-3 (n-3), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA)) was analysed with a gas chromatography-mass spectrometry combination.

RESULTS

From the first trimester to third trimester of pregnancy, a significant increase in total SFA, total MUFA and total n-6 PUFA was found. (p < 0.001). Nevertheless, the serum concentration of arachidonic acid (AA), eicosapentaenoic acid (EPA) and total n-3 PUFA decreased during gestation (p < 0.001). A statistically non-significant result was observed for the docosahexaenoic acid (DHA) serum concentration between the first and third trimesters of pregnancy. Significant correlations were observed between each total fatty acid concentrations of the first and third trimesters.

CONCLUSION

The circulating serum concentration of SFA, MUFA and n-6 PUFA increases during pregnancy, whereas essential fatty acids such as AA and EPA decrease, and DHA remains unchanged. Further research is necessary to understand the role played by FA throughout gestation.

Effects of extra virgin olive oil and pecans on plasma fatty acids in patients with stable coronary artery disease

OBJECTIVE

The aim of this study was to determine the effects of a healthy diet supplemented with extra virgin olive oil or pecans on plasma fatty acids (PFAs) in patients with stable coronary artery disease (CAD).

METHODS

Patients 40 to 80 y of age were randomized to one of three dietary interventions (allocation ratio 1: 1: 1): healthy diet based on guidelines (control group [CG]), healthy diet supplemented with 30 g/d of pecans (PNG), or a healthy diet supplemented with 30 mL/d of extra virgin olive oil (OOG). PFAs were identified at baseline and at the end of follow-up (12 wk), and correlations between dietary fatty acids intake, PFAs, and clinical biomarkers of the lipid profile were also assessed before and after the interventions.

RESULTS

Among 149 participants included in the analysis (43 CG; 51 PNG; and 55 OOG), correlations were observed between food intake, PFAs, and lipid profile before and after interventions independent of statins used, but all were considered weak. At the end of the study, the OOG showed increased concentrations of oleic fatty acid independently of the type of statin in use (1.49%; 95% confidence interval, 0.08-2.89; P = 0.029); however, there were no significant differences between the groups regarding the final mean values of oleic fatty acid or in the other PFAs.

CONCLUSIONS

In patients with stable CAD, there were no significant differences in PFAs after 12 wk according to dietary interventions evaluated.

The influence of nutritional state on the fatty acid composition of circulating lipid fractions: implications for their use as biomarkers of dietary fat intake

BACKGROUND

The fatty acid (FA) composition of blood can be used as an objective biomarker of dietary FA intake. It remains unclear how the nutritional state influences the FA composition of plasma lipid fractions, and thus their usefulness as biomarkers in a non-fasted state.

OBJECTIVES

To investigate the associations between palmitate, oleate and linoleate in plasma lipid fractions and self-reported dietary FA intake, and assess the influence of meal consumption on the relative abundance of these FA in plasma lipid fractions (i.e. triglyceride [TG], phospholipids [PLs] and cholesterol esters [CEs]).

DESIGN

Analysis was performed in plasma samples collected from 49 (34 males and 15 females) participants aged 26-57 years with a body mass index (BMI) between 21.6 and 34.2 kg/m², all of whom had participated in multiple study visits, thus a pooled cohort of 98 data sets was available for analysis. A subset (n = 25) had undergone nutritional interventions and was therefore used to investigate the relationship between the FA composition of plasma lipid fractions and dietary fat intake.

RESULTS

Significant (P < 0.05) positive associations were observed between dietary polyunsaturated fat and linoleate abundance in plasma CE. When investigating the influence of meal consumption on postprandial FA composition, we found plasma TG palmitate significantly (P < 0.05) decreased across the postprandial period, whereas oleate and linoleate increased. A similar pattern was observed in plasma PL, whereas linoleate abundance decreased in the plasma CE.

CONCLUSION

Our data demonstrate that the FA composition of plasma CE may be the lipid fraction to utilise as an objective biomarker when investigating recent (i.e. previous weeks-months) dietary FA intakes. In addition, we show that the consumption of a high-fat meal influences the FA composition of plasma TG, PL and CE over the course of the postprandial period, and therefore, suggest that fasting blood samples should be utilised when using FA composition as a biomarker of dietary FA intake.

Examining the association between serum free fatty acids and blood levels of testosterone

BACKGROUND

Multiple studies have uncovered the effects that ingested fat has on human blood levels of testosterone. Yet, few reports have discussed the effect of circulating serum free fatty acids (FFAs). The present study aimed to explore the relationship between serum free fatty acids and blood levels of testosterone.

METHODS

In total, 5719 adults were pooled from the database of the National Health and Nutrition Examination Survey (NHANES) from 2011 to 2012. Based on multivariable-linear regression models, we employed a total of 30 FFAs to interpret the relationship of FFAs with blood levels of testosterone. Two models with covariate adjustments were designated for further evaluation and analysis.

RESULTS

Capric acid [β = -0.014, 95% confidence interval (CI) = -0.023, -0.004, P = 0.005], myristic acid (β = -0.001, 95% CI = -0.001, 0.000, P ≤ 0.001), pentadecanoic acid (β = -0.013, 95% CI = -0.018, -0.008, P ≤ 0.001), margaric acid (β = -0.011, 95% CI = -0.017, -0.005, P ≤ 0.001) and alpha-linolenic acid (β = -0.001, 95% CI = -0.002, 0.000, P = 0.004) in the fully adjusted model were significantly negatively correlated with the testosterone level inh obese men. In the fully adjusted model for the female analysis, myristic acid, pentadecanoic acid, palmitic acid, margaric acid, stearic acid, myristoleic acid, oleic acid, nervonic acid and alpha-linolenic acid were found significantly associated with the testosterone level.

CONCLUSIONS

Our findings indicate a significant negative correlation between serum FFAs and blood levels of testosterone. Furthermore, we reveal the essentiality of serum FFAs and their potential effects on the reduction of testosterone levels.

Appraising causal relationships of dietary, nutritional and physical-activity exposures with overall and aggressive prostate cancer: two-sample Mendelian-randomization study based on 79 148 prostate-cancer cases and 61 106 controls

BACKGROUND

Prostate cancer is the second most common male cancer worldwide, but there is substantial geographical variation, suggesting a potential role for modifiable risk factors in prostate carcinogenesis.

METHODS

We identified previously reported prostate cancer risk factors from the World Cancer Research Fund (WCRF)'s systematic appraisal of the global evidence (2018). We assessed whether each identified risk factor was causally associated with risk of overall (79 148 cases and 61 106 controls) or aggressive (15 167 cases and 58 308 controls) prostate cancer using Mendelian randomization (MR) based on genome-wide association-study summary statistics from the PRACTICAL and GAME-ON/ELLIPSE consortia. We assessed evidence for replication in UK Biobank (7844 prostate-cancer cases and 204 001 controls).

RESULTS

WCRF identified 57 potential risk factors, of which 22 could be instrumented for MR analyses using single nucleotide polymorphisms. For overall prostate cancer, we identified evidence compatible with causality for the following risk factors (odds ratio [OR] per standard deviation increase; 95% confidence interval): accelerometer-measured physical activity, OR = 0.49 (0.33-0.72; P = 0.0003); serum iron, OR = 0.92 (0.86-0.98; P = 0.007); body mass index (BMI), OR = 0.90 (0.84-0.97; P = 0.003); and monounsaturated fat, OR = 1.11 (1.02-1.20; P = 0.02). Findings in our replication analyses in UK Biobank were compatible with our main analyses (albeit with wide confidence intervals). In MR analysis, height was positively associated with aggressive-prostate-cancer risk: OR = 1.07 (1.01-1.15; P = 0.03).

CONCLUSIONS

The results for physical activity, serum iron, BMI, monounsaturated fat and height are compatible with causality for prostate cancer. The results suggest that interventions aimed at increasing physical activity may reduce prostate-cancer risk, although interventions to change other risk factors may have negative consequences on other diseases.

Lipid composition modulates the intestine digestion rate and serum lipid status of different edible oils: a combination of in vitro and in vivo studies

The objective of the present study was to investigate the connections between lipid compositions and the digestion and absorption differences of different lipids. Five typical edible oils (palm oil, PO; leaf lard oil, LO; rapeseed oil, RO; sunflower oil, SO; linseed oil, LINO) were selected to conduct in vitro digestion experiments considering the lipid digestion extent and hydrolysis rate before analyzing the fatty acid composition and TAG profiles using GC and UHPLC-Q-TOF-MS/MS. Meanwhile, the postprandial lipid absorption status after gavage administration was examined in adult male Sprague-Dawley rats with respect to serum lipid profiles. The results showed that the maximum FFA release extent decreased in the order: PO > RO > LINO > SO > LO, and the FFA release apparent constants were PO > SO ≈ RO > LO ≈ LINO. This suggested that the fatty acid species and the location of fatty acids within TAG molecules could significantly affect the lipid digestion fates in the gastrointestinal tract, and short chain saturated fatty acids located at the Sn-1, 3 position could favor the lipid digestion process. PO and LO were both shown to be more likely to affect the serum TG levels and LDL-C : HDL-C ratio compared with RO, SO and LINO. Different fatty acids displayed different correlations with serum lipid profiles when examined by Pearson correlation analysis. This suggested that fatty acid composition and TAG profiles may influence first the digestion rate and then the serum lipid profiles. This further confirmed that lipid composition could modulate the digestion and absorption status under the gastrointestinal conditions. These findings may provide some basic understanding of the connections between lipid composition and their functional difference.