Substitutions of saturated fat intakes with other macronutrients and foods and risk of NAFLD cirrhosis and all-cause hepatocellular carcinoma: a prospective cohort study.

BACKGROUND: Short-term trials have shown a reduction in liver fat when saturated fatty acids (SFAs) are substituted with polyunsaturated fatty acids (PUFA), or with low-glycemic carbohydrates. However, few cohort studies have been conducted to investigate the associations of replacing SFA and SFA-rich foods with different macronutrients and foods in more severe stages of liver disease; nonalcoholic fatty liver disease (NAFLD) cirrhosis and hepatocellular carcinoma (HCC). OBJECTIVES: To investigate associations between the substitution of SFA and SFA-rich foods with other macronutrients and foods and NAFLD cirrhosis and HCC in a middle-aged to elderly Swedish population of n = 77,059 males and females. METHODS: Time-to-event analyses were performed to investigate associations between the food and macronutrient substitutions and NAFLD cirrhosis and HCC. Multivariable Cox regression models were constructed to estimate hazard ratios (HRs) with corresponding 95% confidence intervals (CIs). Statistical isocaloric and equal-mass substitutions were performed using the leave-one-out method. Prespecified nutrient and food substitutions of interest were SFA with carbohydrates, SFA with fiber, SFA with PUFA, butter with margarine and vegetable oils, unprocessed red meat with fish, and milk with fermented milk. RESULTS: Over a median follow-up of 24 y, 566 cases of NAFLD cirrhosis and 205 cases of HCC were registered. Overall, dietary substitutions showed no clear associations with either NAFLD cirrhosis or HCC. Substituting SFA with carbohydrates showed an HR of 0.87 (95% CI: 0.74, 1.02) for HCC and 1.00 (95% CI: 0.89, 1.11) for NAFLD cirrhosis. Substituting milk with fermented milk showed an HR of 0.93 (95% CI: 0.85, 1.01) for HCC and 0.97 (95% CI: 0.92, 1.03) for NAFLD cirrhosis. CONCLUSIONS: No clear associations were observed between diet and NAFLD cirrhosis or HCC. Although accompanied by low precision, possible lowered risks of HCC by substituting SFA with carbohydrates or milk with fermented milk might be of interest, but needs replication in other cohorts.

Overfeeding polyunsaturated fat compared with saturated fat does not differentially influence lean tissue accumulation in individuals with overweight: a randomized controlled trial.

BACKGROUND: Fatty acids may influence lean tissue volume and skeletal muscle function. We previously reported in young lean participants that overfeeding PUFA compared with SFA induced greater lean tissue accumulation despite similar weight gain. OBJECTIVES: In a double-blind randomized controlled trial, we aimed to investigate if the differential effects of overfeeding SFA and PUFA on lean tissue accumulation could be replicated in individuals with overweight and identify potential determinants. Further, using substitution models, we investigated associations between SFA and PUFA concentrations with lean tissue volume in a large population-based sample (UK Biobank). METHODS: Sixty-one males and females with overweight [BMI (kg/m2): 27.3 (interquartile range (IQR), 25.4-29.3); age: 43 (IQR, 36-48)] were overfed SFA (palm oil) or n-6 (ω-6) PUFA (sunflower oil) for 8 wk. Lean tissue was assessed by MRI. We had access to n = 13,849 participants with data on diet, covariates, and MRI measurements of lean tissue, as well as 9119 participants with data on circulating fatty acids in the UK Biobank. RESULTS: Body weight gain mean (SD) was similar in PUFA (2.01 ± 1.90 kg) and SFA (2.31 ± 1.38 kg) groups. Lean tissue increased to a similar extent [0.54 ± 0.93 L and 0.67 ± 1.21 L for PUFA and SFA groups, respectively, with a difference between groups of 0.07 (-0.21, 0.35)]. We observed no differential effects on circulating amino acids, myostatin, or IL-15 and no clear determinants of lean tissue accumulation. Similar nonsignificant results for SFA and PUFA were observed in UK Biobank, but circulating fatty acids demonstrated ambiguous and sex-dependent associations. CONCLUSIONS: Overfeeding SFA or PUFA does not differentially affect lean tissue accumulation during 8 wk in individuals with overweight. A lack of dietary fat type-specific effects on lean tissue is supported by specified substitution models in a large population-based cohort consuming their habitual diet. This trial was registered at clinicaltrials.gov identifier as NCT02211612.

Substitution analyses of foods with varying fat quality and the associations with all-cause mortality and impact of the FADS-1 genotype in elderly men.

PURPOSE: To investigate associations between substitutions of foods varying in fat quality and all-cause mortality in elderly Swedish men and to examine effect measure modification by a gene involved in fatty acid desaturation (rs174550 FADS1). METHODS: Using Cox-regression models in the ULSAM cohort (n = 1133 men aged 71), we aimed to investigate; (1) Associations between the substitution of a nutrient or food for another on all-cause mortality (primary outcome) and CVD (secondary outcome) and (2) Associations between the addition of various fat-rich foods to the habitual diet and all-cause mortality and CVD. Subgroup analyses based on the rs174550 FADS1 genotype were conducted. RESULTS: Over a mean follow-up of 11.6-13.7 years, n = 774 died and n = 494 developed CVD, respectively. No clear associations were observed for the vast majority of substitution nor addition models. Adding saturated fatty acids (SFA) on top of the habitual diet was however associated with an increased risk of mortality in men with the CT/CC-genotype [HR (95% CI) 1.44 (1.05, 1.97)]. Post-hoc analyses showed an inverse association of substituting SFA with carbohydrates [HR (95% CI) 0.79 (0.65, 0.97)], which was somewhat stronger in men with the CT/CC-genotype compared to men carrying the TT-genotype. CONCLUSIONS: Few associations were observed between diet and all-cause mortality and CVD in this population. However, substituting SFA with carbohydrates was associated with lower mortality in post-hoc analyses and adding SFA to the habitual diet increased mortality in men with the CT/CC-genotype. The latter observation is novel and warrants further investigation in larger cohort studies including women.

Diet composition, nutrient substitutions and circulating fatty acids in relation to ectopic and visceral fat depots.

BACKGROUND & AIMS: Short-term randomized trials have demonstrated that replacing saturated fat (SFA) with polyunsaturated fat (PUFA) causes a reduction or prevention of liver fat accumulation, but population-based studies on diet and body fat distribution are limited. We investigated cross-sectional associations between diet, circulating fatty acids and liver fat, visceral adipose tissue (VAT), intermuscular adipose tissue (IMAT) and other fat depots using different energy-adjustment models. METHODS: Sex-stratified analyses of n = 9119 (for serum fatty acids) to 13 849 (for nutrients) participants in UK Biobank were conducted. Fat depots were assessed by MRI, circulating fatty acids by NMR spectroscopy and diet by repeated 24-h recalls. Liver fat, VAT and IMAT were primary outcomes; total adipose tissue (TAT) and abdominal subcutaneous adipose tissue (ASAT) were secondary outcomes. Three a priori defined models were constructed: the all-components model, standard model and leave-one-out model (main model including specified nutrient substitutions). Imiomics (MRI-derived) was used to confirm and visualize associations. RESULTS: In women, substituting carbohydrates and free sugars with saturated fat (SFA) was positively associated with liver fat (ß (95% CI) = 0.19 (0.02, 0.36) and ß (95% CI) = 0.20 (0.05-0.35), respectively) and IMAT (ß (95% CI) = 0.07 (0.00, 0.14) and ß (95% CI) = 0.08 (0.02, 0.13), respectively), whereas substituting animal fat with plant fat was inversely associated with IMAT, ASAT and TAT. In the all-components and standard models, SFA and animal fat were positively associated with liver fat, IMAT and VAT whereas plant fat was inversely associated with IMAT in women. Few associations were observed in men. Circulating polyunsaturated fatty acids (PUFA) were inversely associated with liver fat, IMAT and VAT in both men and women, whereas SFA and monounsaturated fatty acids were positively associated. CONCLUSIONS: Type of dietary fat may be an important determinant of ectopic fat in humans consuming their habitual diet. Plant fat and PUFA should be preferred over animal fat and SFA. This is corroborated by circulating fatty acids and overall consistent through different energy adjustment models. TWITTER SUMMARY: In UK Biobank, intake of saturated- and animal fat were positively whereas biomarkers of polyunsaturated fat were inversely associated with liver-, visceral- and intermuscular fat. Type of dietary fat may be a determinant of ectopic fat, a risk factor for cardiometabolic disease.

Contrasting Carbohydrate Quantity and Quality and the Effects on Plasma Saturated and Monounsaturated Fatty Acids in Healthy Adults: A Randomized Controlled Trial.

BACKGROUND: It is unclear whether moderate differences in dietary carbohydrate quantity and quality influence plasma FAs in the lipogenic pathway in healthy adults. OBJECTIVES: We investigated the effects of different carbohydrate quantities and quality on plasma palmitate concentrations (primary outcome) and other saturated and MUFAs in the lipogenic pathway. METHODS: Twenty healthy participants were randomly assigned, and 18 (50% women; age: 22-72 y; BMI: 18.2-32.7 kg/m2 and BMI was measured in kg/m2) started the cross-over intervention. During each 3-wk period (separated by a 1-wk washout period), 3 diets were consumed (all foods provided) in random order: low-carbohydrate (LC) (38% energy (E) carbohydrates, 25-35 g fiber/d, 0% E added sugars); high-carbohydrate/high-fiber (HCF) (53% E carbohydrates, 25-35 g fiber/d, 0% E added sugars); and high-carbohydrate/high-sugar (HCS) (53% E carbohydrates, 19-21 g fiber/d, 15% E added sugars). Individual FAs were measured proportionally to total FAs by GC in plasma cholesteryl esters, phospholipids, and TGs. False discovery rate-adjusted repeated measures ANOVA [ANOVA-false discovery rate (FDR)] was used to compare outcomes. RESULTS: The self-reported intakes of carbohydrates and added- and free sugars were; 30.6% E and 7.4% E in LC, 41.4% E and 6.9% E in HCF, and 45.7% E and 10.3% in HCS. Plasma palmitate did not differ between the diet periods (ANOVA FDR P > 0.43, n = 18). After HCS, myristate concentrations in cholesterol esters and phospholipids were ≥19% higher than LC and ≥22% higher than HCF (P = 0.005). After LC, palmitoleate in TG was 6% lower compared with HCF and 7% compared with HCS (P = 0.041). Body weight differed (≤0.75 kg) between diets before FDR correction. CONCLUSIONS: Different carbohydrate quantity and quality do not influence plasma palmitate concentrations after 3 wk in healthy Swedish adults, whereas myristate increased after the moderately higher intake of carbohydrate/high-sugar, but not carbohydrate/high-fiber. Whether plasma myristate is more responsive than palmitate to differences in carbohydrate intake requires further study, especially considering that participants deviated from the planned dietary targets. J Nutr 20XX;xx:xx-xx. This trial was registered at clinicaltrials.gov as NCT03295448.

Circulating fatty acids from high-throughput metabolomics platforms as potential biomarkers of dietary fatty acids.

BACKGROUND: Some fatty acids, i.e. n-3 and n-6 polyunsaturated fatty acids (PUFA), from metabolomics platforms based on nuclear magnetic resonance imaging (NMR) or liquid chromatography mass-spectrometry (LC-MS) are suggested to reflect dietary exposure. NMR and LC-MS are both relatively fast and cheap, however few studies have investigated their validity. Linoleic acid (LA) and docosahexaenoic acid (DHA), measured using gas chromatography (GC), are established biomarkers of dietary n-6 and n-3 PUFA intake, respectively. OBJECTIVE: To examine if circulating fatty acids derived from two commonly applied metabolomics platforms (using NMR and LC-MS) provide similar information compared to GC in two pooled population-based cohorts, one patient cohort, and in a randomized controlled trial (RCT). METHODS: Spearman rank correlations were conducted between LA and DHA in cholesteryl esters (CE) from GC and whole serum/plasma LA and DHA from the metabolomics platforms in a pooled population-based cohort of men and women (n Ëœ 1100) (primary analysis). Secondary correlation analyses included fatty acid classes such as n-3 PUFA, n-6 PUFA, saturated fatty acids (SFA), monounsaturated fatty acids (MUFA) and total PUFA. Additionally, correlations were investigated for LA, DHA and the five fatty acid classes in phospholipids (PL), triacylglycerols (TAG) and non-esterified fatty acids (NEFA) in a RCT of n = 60 as well as in a population with biopsy-verified non-alcoholic fatty liver disease (NAFLD) (n = 59). Misclassification was examined using cross-tabulation and visualized using alluvial plots. RESULTS: Moderate to strong correlations (r = 0.51-0.81) were observed for LA and DHA in multiple lipid fractions in all cohorts using the NMR platform. For the pooled cohort, LA (r = 0.67, P < 0.0001) and DHA (r = 0.68, P < 0.0001) assessed in CE were strongly correlated with LA and DHA derived using NMR. Nearly half (49%) were correctly classified into their respective quartiles. Using LC-MS, only DHA (r = 0.44, P < 0.0001) demonstrated moderate correlations with DHA from GC. CONCLUSIONS: Unless fatty acid data from GC analysis is available or feasible, NMR-based technology might be a better option than a LC-MS-based platform, at least for certain PUFA. This should be taken into account in future studies aiming to use circulating fatty acids as dietary biomarkers for the investigation of diet-disease relationships.

Intake of Ultra-Processed Food and Ectopic-, Visceral- and Other Fat Depots: A Cross-Sectional Study.

Introduction: The purpose of this study was to investigate associations between intake of ultra-processed food (UPF) and liver fat, pancreas fat and visceral adipose tissue (VAT) but also subcutaneous adipose tissue (SAT), VAT/SAT ratio and total fat mass. Materials and Methods: Cross-sectional analysis of n = 286 50-year old men and women. Energy percentage (%E) from UPF was calculated from a semi-quantitative food frequency questionnaire. Food items were categorized according to the NOVA-classification system and fat depots were assessed using magnetic resonance imaging (MRI) and bioelectrical impedance analysis (BIA). Associations were analyzed using linear regression, adjusted for sex, education, physical activity, smoking, dietary factors and BMI. Results: Mean intake of UPF was 37.8 ± 10.2 %E and the three largest contributors to this were crisp- and wholegrain breads and spreads, indicating overall healthy food choices. Consumption of UPF was associated with higher intake of energy, carbohydrates and fiber and lower intake of protein and polyunsaturated fat but no differences were observed for total fat, saturated fat (SFA), monounsaturated fat, sugar or alcohol between tertiles of UPF. Intake of UPF was positively associated with liver- and pancreas fat, VAT, VAT/SAT and inversely associated with total fat mass in crude models. The association for VAT remained after full adjustment (ß = 0.01 (95% CI: 0.002, 0.02), P = 0.02) and was driven by women. Conclusion: Energy intake from UPF is not associated with ectopic fat, SAT or total fat after adjustment for multiple confounders in this population having overall healthy food habits. However, a positive association between UPF and VAT was observed which was driven by women.

Fatty acids in multiple circulating lipid fractions reflects the composition of liver triglycerides in humans.

BACKGROUND AND AIMS: Fatty acids (e.g. 16:1n-7) and desaturase indices (e.g. stearoyl-CoA desaturase, SCD) in plasma cholesteryl esters (CE) and phospholipids (PL) are used as biomarkers of dietary fat quality and lipid metabolism and are associated with disease outcomes. Endogenously produced circulating fatty acids are believed to reflect composition of the liver, yet little data exist to support such relationship. We investigated associations between circulating fatty acids and fatty acids within the liver. METHODS: Liver biopsies and blood were collected from n = 60 patients with non-alcoholic fatty liver disease. Fatty acids in CE, PL and triglycerides (TG) in plasma and liver were analyzed using gas chromatography. Associations were assessed using Spearman rank correlations. RESULTS: Overall, fatty acids and desaturase indices in plasma PL and TG showed moderate-strong correlations with fatty acids and desaturase indices in corresponding lipid fractions in liver. For plasma CE, 16:1n-7 and SCD were correlated with 16:1n-7 and SCD in liver CE. Noteworthy, fatty acids in plasma CE and PL also showed moderate-strong correlations with fatty acids in liver TG (e.g. r = 0.82-0.87 for 16:1n-7 and r = 0.77 for SCD). CONCLUSION: We demonstrate that fatty acids in circulating lipid fractions, including CE, TG and PL, reflects the composition of liver TG in humans, suggesting that circulating fatty acids might be useful biomarkers for the fatty acid composition of the liver. As liver tissue is rarely available in cohort studies, our findings could enhance our understanding of plasma fatty acids as markers of hepatic lipid metabolism and their links to metabolic diseases.

Associations between fatty acid composition in serum cholesteryl esters and liver fat, basal fat oxidation, and resting energy expenditure: a population-based study.

BACKGROUND: We have repeatedly shown in short-term feeding trials that a high intake of dietary n-6 PUFAs, i.e. linoleic acid, prevents liver fat accumulation compared with saturated fat. However, population-based data is lacking and the mechanisms behind such effects are unclear. OBJECTIVE: To investigate associations between serum cholesteryl ester (CE) fatty acids and liver fat, basal fat oxidation [respiratory quotient (RQ)], and resting energy expenditure (REE). We hypothesized that PUFA in particular is inversely associated with liver fat and that such a relation is partly explained by a PUFA-induced increase in basal fat oxidation or REE. METHODS: Cross-sectional analyses using linear regression models in a population-based cohort with data on serum CE fatty acid composition and liver fat (n = 308). RESULTS: Linoleic acid (18:2n-6) (ß = -0.03, 95% CI: -0.06, -0.001) and Δ5 desaturase index were inversely associated, whereas, γ-linolenic acid (18:3n-6) (ß = 0.59, 95% CI: 0.28, 0.90), dihomo-γ-linolenic acid (20:3n-6) (ß = 1.20, 95% CI: 0.65, 1.75), arachidonic acid (20:4n-6) (ß = 0.08, 95% CI: 0.002, 0.16), palmitoleic acid (16:1n-7) (ß = 0.37, 95% CI: 0.04, 0.70), Δ6 desaturase, and stearoyl CoA desaturase-1 (SCD-1) index were directly associated with liver fat after adjustment for confounders. Several serum CE fatty acids were correlated with both liver fat and REE, but only the association between DHA (22:6n-3) and liver fat was clearly attenuated after adjustment for REE (from ß = -0.63 95% CI: -1.24, -0.02 to ß = -0.34, 95% CI: -0.95, 0.27). Palmitoleic acid and SCD-1 were weakly inversely correlated with RQ but could not explain a lower liver fat content. CONCLUSIONS: Several serum CE fatty acids are associated with liver fat, among them linoleic acid. Although we identified novel associations between individual fatty acids and RQ and REE, our findings imply that PUFAs might prevent liver fat accumulation through mechanisms other than enhanced whole-body energy metabolism.

Hepatic Unsaturated Fatty Acids Are Linked to Lower Degree of Fibrosis in Non-alcoholic Fatty Liver Disease.

Background: The hepatic lipidome of patients with early stages of non-alcoholic fatty liver disease (NAFLD) has been fairly well-explored. However, studies on more progressive forms of NAFLD, i.e., liver fibrosis, are limited. Materials and methods: Liver fatty acids were determined in cholesteryl esters (CE), phospholipids (PL), and triacylglycerols (TAG) by gas chromatography. Cross-sectional associations between fatty acids and biopsy-proven NAFLD fibrosis (n = 60) were assessed using multivariable logistic regression models. Stages of fibrosis were dichotomized into none-mild (F0-1) or significant fibrosis (F2-4). Models were adjusted for body-mass index (BMI), age and patatin-like phospholipase domain-containing protein 3 (PNPLA3 rs738409) (I148M) genotype. A secondary analysis examined whether associations from the primary analysis could be confirmed in the corresponding plasma lipid fractions. Results: PL behenic acid (22:0) was directly associated [OR (95% CI): 1.86 (1.00, 3.45)] whereas PL docosahexaenoic acid (22:6n-3) [OR (95% CI): 0.45 (0.23, 0.89)], TAG oleic acid (18:1n-9) [OR (95% CI): 0.52 (0.28, 0.95)] and 18:1n-9 and vaccenic acid (18:1n-7) (18:1) [OR (95% CI): 0.52 (0.28, 0.96)] were inversely associated with liver fibrosis. In plasma, TAG 18:1n-9 [OR (95% CI): 0.55 (0.31, 0.99)], TAG 18:1 [OR (95% CI): 0.54 (0.30, 0.97)] and PL 22:0 [OR (95% CI): 0.46 (0.25, 0.86)] were inversely associated with liver fibrosis. Conclusion: Higher TAG 18:1n-9 levels were linked to lower fibrosis in both liver and plasma, possibly reflecting an altered fatty acid metabolism. Whether PL 22:6n-3 has a protective role, together with a potentially adverse effect of hepatic 22:0, on liver fibrosis warrants large-scale studies.