Different effects of palmitic and stearic acid-enriched diets on serum lipids and lipoproteins and plasma cholesteryl ester transfer protein activity in healthy young women

Saturated fatty acid biomarkers and risk of cardiometabolic diseases: A meta-analysis of prospective studies

Background and aims

Evidence regarding associations of circulating saturated fatty acids (SFAs) with chronic diseases is mixed. The objective of this study was to determine the associations between total or individual SFA biomarkers and the risk of cardiometabolic diseases.

Methods

Four electronic databases were searched from inception to March 2022. Three investigators independently assessed for inclusion and extracted data. Random-effects or fixed-effects models was used to estimate the pooled relative risks (RRs) and corresponding 95% confidence intervals (CIs) for the association of total or individual SFA biomarkers, including even-chain SFAs (e.g., 14:0, myristic acid; 16:0, palmitic acid; 18:0, stearic acid), odd-chain SFAs (e.g., 15:0, pentadecanoic acid; 17:0, margaric acid) and very-long-chain SFAs (VLCSFAs; e.g., 20:0, arachidic acid; 22:0, behenic acid; 24:0, lignoceric acid), with risk of incident type 2 diabetes (T2D), cardiovascular disease [CVD; coronary heart disease (CHD) inclusive of stroke], CHD and stroke.

Results

A total of 49 prospective studies reported in 45 articles were included. Higher concentration of circulating total SFAs was associated with an increasing risk of cardiometabolic diseases, the risk increased significantly by 50% for CVD (95%CI:1.31–1.71), 63% for CHD (95%CI:1.38–1.94), 38% for stroke (95%CI:1.05–1.82), respectively. Similarly, levels of even-chain SFAs were positively associated with higher risk of chronic diseases, with RRs ranging from 1.15 to 1.43. In contrast, the risk of cardiometabolic diseases was reduced with increasing odd-chain SFA levels, with RRs ranging from 0.62 to 0.91. A higher level of VLCSFAs corresponded to 19% reduction in CVD. Further dose-response analysis indicated that each 50% increment in percentage of total SFAs in circulating was associated with an 8% higher risk of T2D (RR: 1.08, 95%CI: 1.02–1.14) and trends toward higher risk of CVD (RR: 1.15, 95%CI: 0.98–1.34). Inverse linear relationships were observed between 17:0 biomarker and T2D or CVD risk.

Conclusion

Our findings support the current recommendations of reducing intake of saturated fat as part of healthy dietary patterns. Further studies are needed to confirm our findings on these SFAs in relation to cardiometabolic outcomes and to elucidate underlying mechanisms.

Systematic review registration

[https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42022329182], identifier [CRD42022329182].

Impact of Replacement of Individual Dietary SFAs on Circulating Lipids and Other Biomarkers of Cardiometabolic Health: A Systematic Review and Meta-Analysis of Randomized Controlled Trials in Humans

Little is known of the impact of individual SFAs and their isoenergetic substitution with other SFAs or unsaturated fatty acids (UFAs) on the prevention of cardiometabolic disease (CMD). This systematic literature review assessed the impact of such dietary substitutions on a range of fasting CMD risk markers, including lipid profile, markers of glycemic control and inflammation, and metabolic hormone concentrations. Eligible randomized controlled trials (RCTs) investigated the effect of isoenergetic replacements of individual dietary SFAs for ≥14 d on ≥1 CMD risk markers in humans. Searches of the PubMed, Embase, Scopus, and Cochrane CENTRAL databases on 14 February, 2021 identified 44 RCTs conducted in participants with a mean ± SD age of 39.9 ± 15.2 y. Studies' risk of bias was assessed using the Cochrane Risk of Bias tool 2.0 for RCTs. Random-effect meta-analyses assessed the effect of ≥3 similar dietary substitutions on the same CMD risk marker. Other dietary interventions were described in qualitative syntheses. We observed reductions in LDL-cholesterol concentrations after the replacement of palmitic acid (16:0) with UFAs (-0.36 mmol/L; 95% CI: -0.50, -0.21 mmol/L; I2 = 96.0%, n = 18 RCTs) or oleic acid (18:1n-9) (-0.16 mmol/L; 95% CI: -0.28, -0.03 mmol/L; I2 = 89.6%, n = 9 RCTs), with a similar impact on total cholesterol and apoB concentrations. No effects on other CMD risk markers, including HDL-cholesterol, triacylglycerol, glucose, insulin, or C-reactive protein concentrations, were evident. Similarly, we found no evidence of a benefit from replacing dietary stearic acid (18:0) with UFAs on CMD risk markers (n = 4 RCTs). In conclusion, the impact of replacing dietary palmitic acid with UFAs on lipid biomarkers is aligned with current public health recommendations. However, owing to the high heterogeneity and limited studies, relations between all individual SFAs and biomarkers of cardiometabolic health need further confirmation from RCTs. This systematic review was registered at www.crd.york.ac.uk/prospero/ as CRD42020084241.

Rhynchophorus palmarum (Linnaeus, 1758) (Coleoptera: Curculionidae): Guarani-Kaiowá indigenous knowledge and pharmacological activities

Zootherapy is a traditional secular practice among the Guarani-Kaiowá indigenous ethnic group living in Mato Grosso do Sul, Brazil. My people use the oil extracted from larvae of the snout beetle Rhynchophorus palmarum (Linnaeus, 1758) to treat and heal skin wounds and respiratory diseases. Based on this ethnopharmacological knowledge, the chemical composition and antioxidant, antimicrobial, and healing properties of R. palmarum larvae oil (RPLO) were investigated, as well as possible toxic effects, through in vitro and in vivo assays. The chemical composition of the RPLO was determined using gas chromatography coupled with mass spectrometry. The antioxidant activity of RPLO was investigated through the direct 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay, and the antimicrobial activity was evaluated against Gram-positive and Gram-negative bacteria that are pathogenic to humans. The healing properties of RPLO were investigated by performing a cell migration assay using human lung fibroblasts (MRC-5), and the toxicity was analyzed, in vivo, using a Caenorhabditis elegans model and MRC-5 cells, in vitro. RPLO contains 52.2% saturated fatty acids and 47.4% unsaturated fatty acids, with palmitic acid (42.7%) and oleic acid (40%) representing its major components, respectively. RPLO possesses direct antioxidant activity, with a half-maximal inhibitory concentration (IC50) of 46.15 mg.ml-1. The antimicrobial activity of RPLO was not observed at a concentration of 1% (v/v). RPLO did not alter the viability of MRC-5 cells and did not exert toxic effects on C. elegans. Furthermore, MRC-5 cells incubated with 0.5% RPLO showed a higher rate of cell migration than that of the control group, supporting its healing properties. Taken together, RPLO possesses direct antioxidant activity and the potential to aid in the healing process and is not toxic toward in vitro and in vivo models, corroborating the safe use of the oil in traditional Guarani-Kaiowá medicine.

Does variation in serum LDL-cholesterol response to dietary fatty acids help explain the controversy over fat quality and cardiovascular disease risk?

Controversy over fat quality and cardiovascular disease risk stems from a series of meta-analyses of prospective cohort and randomised intervention trials, which found little evidence for a significant relationship between the intake of saturated fat and disease endpoints. Possible explanations for these null findings include difficulties inherent in estimating true food intake, the confounding effects of macronutrient replacement and food composition, and marked inter-individual variation in the response of serum LDL-cholesterol. The aim of this narrative review was to present evidence for the existence and origins of variation in serum LDL-cholesterol response to the replacement of dietary saturated fat, and its potential to explain the controversy over the latter. The review provides evidence to suggest that variation in LDL-responsiveness may harbour significant potential to confound the relationship between saturated fat and atherosclerotic cardiovascular disease risk, thus undermining the effectiveness of the dietary guideline to replace saturated fat with unsaturated fat. It concludes that the identification and application of a simple biomarker of this phenomenon, would make it possible to tailor dietary guidelines to LDL responsive individuals, who stand to gain a greater benefit to their cardiovascular health.

Oleic acid to stearic acid ratio might be a potential marker for insulin resistance in non-obese Japanese

Results from a recent study indicate that a higher level of oleic acid/stearic acid ratio was associated with metabolically unhealthy obesity. This was further validated in cross-sectional and interventional studies; however, this was not extensively studied in a non-obese population. We recruited 260 Japanese subjects with serum free fatty acid profiles undergoing anti-aging health examinations. The determinants for oleic acid/stearic acid ratio were investigated using multiple regression analyses. To compare different markers, the subjects were classified based on oleic acid/stearic acid ratio and the combination of oleic acid/stearic acid ratio and triglyceride levels. The oleic acid/stearic acid ratio exhibited a positive correlation with the logmatic transformed triglyceride/high-density lipoprotein cholesterol ratio and the fasting triglycerides-glucose index, both of which were used as markers for insulin resistance. Multiple regression analyses revealed that the triglyceride/high-density lipoprotein cholesterol ratio and fasting triglyceride-glucose index were positively associated with the oleic acid/stearic acid ratio. Most markers were the worst in the highest triglyceride group in both oleic acid/stearic acid groups. In addition, most markers were worse in high oleic acid/stearic acid ratio group than low group. In conclusion, oleic acid/stearic acid ratio might be a useful marker for insulin resistance in non-obese Japanese subjects.

Dietary stearic acid and palmitic acid do not differently affect ABCA1-mediated cholesterol efflux capacity in healthy men and postmenopausal women: A randomized controlled trial

BACKGROUND

The saturated fatty acid stearic acid (C18:0) lowers HDL cholesterol compared with palmitic acid (C16:0). However, the ability of HDL particles to promote cholesterol efflux from macrophages (cholesterol efflux capacity; CEC) may better predict coronary heart disease (CHD) risk than HDL cholesterol concentrations.

OBJECTIVE

We examined effects of exchanging dietary palmitic acid for stearic acid on ATP-binding cassette transporter A1 (ABCA1)-mediated CEC, and other conventional and emerging cardiometabolic risk makers.

DESIGN

In a double-blind, randomized, crossover study with two 4-week isocaloric intervention periods, 34 healthy men and postmenopausal women (61.5 ± 5.7 years, BMI: 25.4 ± 2.5 kg/m²) followed diets rich in palmitic acids or stearic acids. Difference in intakes was 6% of daily energy. ABCA1-mediated CEC was measured from J774 macrophages to apolipoprotein (apo)B-depleted serum.

RESULTS

Compared with the palmitic-acid diet, the stearic-acid diet lowered serum LDL cholesterol (-0.14 mmol/L; p = 0.010), HDL cholesterol (-0.09 mmol/L; p=<0.001), and apoA1 (-0.05 g/L; p < 0.001). ABCA1-mediated CEC did not differ between diets (p = 0.280). Cholesteryl ester transfer protein (CETP) mass was higher on stearic acid (0.11 mg/L; p = 0.003), but CETP activity was comparable. ApoB100 did not differ, but triacylglycerol concentrations tended to be higher on stearic acid (p = 0.100). Glucose concentrations were comparable. Effects on insulin and C-peptide were sex-dependent. In women, the stearic-acid diet increased insulin concentrations (1.57 μU/mL; p = 0.002), while in men, C-peptide concentrations were lower (-0.15 ng/mL; p = 0.037). Interleukin 6 (0.15 pg/mL; p = 0.039) and tumor necrosis factor alpha (0.18 pg/mL; p = 0.005), but not high-sensitivity C-reactive protein, were higher on stearic acid. Soluble intracellular adhesion molecule (9 ng/mL; p = 0.033), but not soluble vascular cell adhesion molecule and endothelial-selectin concentrations decreased after stearic-acid consumption.

CONCLUSIONS

As expected, stearic-acid intake lowered LDL cholesterol, HDL cholesterol, and apoA1. Insulin sensitivity in women and low-grade inflammation might be unfavorably affected by stearic-acid intake. However, palmitic-acid and stearic-acid intakes did not differently affect ABCA1-mediated CEC.

CLINICAL TRIAL REGISTRY

This trial was registered at clinicaltrials.gov as NCT02835651.

The combined effects of cholesteryl ester transfer protein (CETP) TaqIB gene polymorphism and canola, sesame and sesame-canola oils consumption on metabolic response in patients with diabetes and healthy people

Introduction: Cholesteryl ester transfer protein (CETP) is a key regulating enzyme in the lipid metabolism pathway, and its gene polymorphism may be a candidate for modulating the metabolic responses to dietary intervention. We thus examined whether the effects of the CETP TaqIB polymorphism on metabolic profiles were modified by dietary plant oils.

Methods: This is a retrospective analysis of data collected during a randomized triple-blind cross over trial. A total of 95 patients with type 2 diabetes and 73 non-diabetes individuals completed a 9-weekof the intake of sesame, canola and sesame-canola oils. Blood samples were collected at the beginning and at the end of each intervention period for biochemical analysis. Genotyping was done using the polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) method.

Results: In diabetes patients, B1B1 homozygotes of the CETP TaqIB polymorphism compared with B2 carriers (B1B2 + B2B2) had significantly lower diastolic blood pressure, apoB and apoB: apoA-1,and higher Lp(a) after the intake of sesame-canola oil, as well as lower insulin and HOMA-IR after the intake of sesame oil. There was also a significant effect of genotype on adjusted changes of apoB, apoB: apoA-1, insulin, HOMA-IR and QUICKI. A significant genotype-dietary oils combined effects were observed for diastolic blood pressure, and LDL: HDL, TC: HDL and TG: HDL ratios in diabetes patients. No independent or combined effects of dietary oils and genotypes on outcomes were found in healthy people.

Conclusion: There was a modulatory effect of the CETP TaqIB polymorphism on some metabolic traits in response to plant oils in patients with diabetes. Taken together, the intake of sesame-canola and canola oils showed more favorable effects in diabetes patients with B1B1 genotype. Future investigations are needed to confirm these results.

Plasma Ceramide Species Are Associated with Diabetes Risk in Participants of the Strong Heart Study

BACKGROUND

Few studies have assessed the associations of ceramides and sphingomyelins (SMs) with diabetes in humans.

OBJECTIVE

We assessed associations of 15 circulating ceramides and SM species with incident diabetes in 2 studies.

METHODS

The analysis included 435 American-Indian participants from the Strong Heart Study (nested case-control design for analyses; mean age: 57 y; 34% male; median time until diabetes 4.3 y for cases) and 1902 participants from the Strong Heart Family Study (prospective design for analyses; mean age: 37 y; 39% male; median 12.5 y of follow-up). Sphingolipid species were measured using stored plasma samples by sequential LC and MS. Using logistic regression and parametric survival models within studies, and an inverse-variance-weighted meta-analysis across studies, we examined associations of 15 ceramides and SM species with incident diabetes.

RESULTS

There were 446 cases of incident diabetes across the studies. Higher circulating concentrations of ceramides containing stearic acid (Cer-18), arachidic acid (Cer-20), and behenic acid (Cer-22) were each associated with a higher risk of diabetes. The RRs for incident diabetes per 1 SD of each log ceramide species (μM) were 1.22 (95% CI: 1.09, 1.37) for Cer-18, 1.18 (95% CI: 1.06, 1.31) for Cer-20, and 1.20 (95% CI: 1.08, 1.32) for Cer-22. Although the magnitude of the risk estimates for the association of ceramides containing lignoceric acid (Cer-24) with diabetes was similar to those for Cer-18, Cer-20, and Cer-22 (RR = 1.13; 95% CI: 1.01, 1.26), the association was not statistically significant after correction for multiple testing (P = 0.007). Ceramides carrying palmitic acid (Cer-16), SMs, glucosyl-ceramides, or a lactosyl-ceramide were not associated with diabetes risk.

CONCLUSIONS

Higher concentrations of circulating Cer-18, Cer-20, and Cer-22 were associated with a higher risk of developing diabetes in 2 studies of American-Indian adults. This trial was registered at clinicaltrials.gov as NCT00005134.

Palmitic Acid Versus Stearic Acid: Effects of Interesterification and Intakes on Cardiometabolic Risk Markers - A Systematic Review

Fats that are rich in palmitic or stearic acids can be interesterified to increase their applicability for the production of certain foods. When compared with palmitic acid, stearic acid lowers low-density lipoprotein (LDL)-cholesterol, which is a well-known risk factor for coronary heart disease (CHD), but its effects on other cardiometabolic risk markers have been studied less extensively. In addition, the positional distribution of these two fatty acids within the triacylglycerol molecule may affect their metabolic effects. The objective was to compare the longer-term and postprandial effects of (interesterified) fats that are rich in either palmitic or stearic acids on cardiometabolic risk markers in humans. Two searches in PubMed/Medline, Embase (OVID) and Cochrane Library were performed; one to identify articles that studied effects of the position of palmitic or stearic acids within the triacylglycerol molecule and one to identify articles that compared side-by-side effects of palmitic acid with those of stearic acid. The interesterification of palmitic or stearic acid-rich fats does not seem to affect fasting serum lipids and (apo) lipoproteins. However, substituting palmitic acid with stearic acid lowers LDL-cholesterol concentrations. Postprandial lipemia is attenuated if the solid fat content of a fat blend at body temperature is increased. How (the interesterification of) palmitic or stearic acid-rich fats affects other cardiometabolic risk markers needs further investigation.

Chocolate, "Food of the Gods": History, Science, and Human Health

Chocolate is well known for its fine flavor, and its history began in ancient times, when the Maya considered chocolate (a cocoa drink prepared with hot water) the "Food of the Gods". The food industry produces many different types of chocolate: in recent years, dark chocolate, in particular, has gained great popularity. Interest in chocolate has grown, owing to its physiological and potential health effects, such as regulation of blood pressure, insulin levels, vascular functions, oxidation processes, prebiotic effects, glucose homeostasis, and lipid metabolism. However, further translational and epidemiologic studies are needed to confirm available results and to evaluate other possible effects related to the consumption of cocoa and chocolate, verifying in humans the effects hitherto demonstrated only in vitro, and suggesting how best to consume (in terms of dose, mode, and time) chocolate in the daily diet.

Comparison of diets enriched in stearic, oleic, and palmitic acids on inflammation, immune response, cardiometabolic risk factors, and fecal bile acid concentrations in mildly hypercholesterolemic postmenopausal women-randomized crossover trial

BACKGROUND

Direct comparisons between SFAs varying in chain length, specifically palmitic acid (16:0) and stearic acid (18:0), relative to the latter's metabolic product, oleic acid (18:1), on cardiometabolic risk factors are limited.

OBJECTIVE

The aim of this study was to determine the relative comparability of diets enriched in palmitic acid, stearic acid, and oleic acid on inflammation and coagulation markers, T lymphocyte proliferation/ex-vivo cytokine secretion, plasma cardiometabolic risk factors, and fecal bile acid concentrations.

METHODS

Hypercholesterolemic postmenopausal women (n = 20, mean ± SD age 64 ± 7 y, BMI 26.4 ± 3.4 kg/m2, LDL cholesterol ≥ 2.8 mmol/L) were provided with each of 3 diets [55% energy (%E) carbohydrate, 15%E protein, 30%E fat, with ∼50% fat contributed by palmitic acid, stearic acid, or oleic acid in each diet; 5 wk/diet phase] using a randomized crossover design with 2-wk washouts between phases. Outcome measures were assessed at the end of each phase.

RESULTS

Fasting LDL-cholesterol and non-HDL-cholesterol concentrations were lower after the stearic acid and oleic acid diets than the palmitic acid diet (all P < 0.01). Fasting HDL-cholesterol concentrations were lower after the stearic acid diet than the palmitic acid and oleic acid diets (P < 0.01). The stearic acid diet resulted in lower lithocholic acid (P = 0.01) and total secondary bile acid (SBA) concentrations (P = 0.04) than the oleic acid diet. All other outcome measures were similar between diets. Lithocholic acid concentrations were positively correlated with fasting LDL-cholesterol concentrations (r = 0.33; P = 0.011). Total SBA, lithocholic acid, and deoxycholic acid concentrations were negatively correlated with fasting HDL cholesterol (r = -0.51 to -0.44; P < 0.01) concentrations and positively correlated with LDL cholesterol:HDL cholesterol (r = 0.37-0.54; P < 0.01) ratios.

CONCLUSIONS

Dietary stearic acid and oleic acid had similar effects on fasting LDL-cholesterol and non-HDL-cholesterol concentrations and more favorable ones than palmitic acid. Unlike oleic acid, the hypocholesterolemic effect of stearic acid may be mediated by inhibition of intestinal hydrophobic SBA synthesis. These findings add to the data suggesting there should be a reassessment of current SFA dietary guidance and Nutrient Facts panel labeling.This trial was registered at clinicaltrials.gov as NCT02145936.

Associations of circulating very-long-chain saturated fatty acids and incident type 2 diabetes: a pooled analysis of prospective cohort studies

BACKGROUND

Saturated fatty acids (SFAs) of different chain lengths have unique metabolic and biological effects, and a small number of recent studies suggest that higher circulating concentrations of the very-long-chain SFAs (VLSFAs) arachidic acid (20:0), behenic acid (22:0), and lignoceric acid (24:0) are associated with a lower risk of diabetes. Confirmation of these findings in a large and diverse population is needed.

OBJECTIVE

We investigated the associations of circulating VLSFAs 20:0, 22:0, and 24:0 with incident type 2 diabetes in prospective studies.

METHODS

Twelve studies that are part of the Fatty Acids and Outcomes Research Consortium participated in the analysis. Using Cox or logistic regression within studies and an inverse-variance-weighted meta-analysis across studies, we examined the associations of VLSFAs 20:0, 22:0, and 24:0 with incident diabetes among 51,431 participants.

RESULTS

There were 14,276 cases of incident diabetes across participating studies. Higher circulating concentrations of 20:0, 22:0, and 24:0 were each associated with a lower risk of incident diabetes. Pooling across cohorts, the RR (95% CI) for incident diabetes comparing the 90th percentile to the 10th percentile was 0.78 (0.70, 0.87) for 20:0, 0.84 (0.77, 0.91) for 22:0, and 0.75 (0.69, 0.83) for 24:0 after adjustment for demographic, lifestyle, adiposity, and other health factors. Results were fully attenuated in exploratory models that adjusted for circulating 16:0 and triglycerides.

CONCLUSIONS

Results from this pooled analysis indicate that higher concentrations of circulating VLSFAs 20:0, 22:0, and 24:0 are each associated with a lower risk of diabetes.

The interaction of cholesteryl ester transfer protein gene variations and diet on changes in serum lipid profiles

BACKGROUND/OBJECTIVES

Gene-diet interactions may have an important role in the disparities between the lipid responses of individuals to diet. This study aimed to investigate whether polymorphisms (rs5882 and rs3764261) in the cholesteryl ester transfer protein (CETP) gene modify the association of diet with changes in serum lipid profiles.

SUBJECTS/METHODS

A total of 4700 individuals aged ≥18 years were selected from among participants of the Tehran Lipid and Glucose Study. After 3.6 years of follow-up, changes in serum lipid profiles were evaluated. Usual dietary intake was assessed using a validated food frequency questionnaire. DNA samples were genotyped with HumanOmniExpress-24-v1-0 bead chips (containing 649,932 SNP loci).

RESULTS

No significant interaction was found between CETP polymorphisms and dietary patterns in changing lipid profiles. Mean changes of total cholesterol (TC) decreased in higher quartiles of fish intake in A allele carriers (Q1:8.02, Q4:5.58, P_trend = 0.01) compared to the CC genotype (Q1:3.65, Q4:8.93, P_trend = 0.11) (P_i = 0.02). There are ascending trends of changes in triglyceride (TG) concentrations across quartiles of total fat, monounsaturated and saturated fat consumption in G allele carriers of rs5882 compared to the AA genotype. There was a declining trend for mean changes in TG concentrations across quartiles of carbohydrate intake in G allele carriers of rs5882 compared to the AA genotype (P_i = 0.01).

CONCLUSIONS

Our data demonstrated that minor allele carriers of rs5882 had a better TG value than AA homozygote individuals when consuming a low fat and high carbohydrate diet. Fish intake modifies the association of rs3764261with TC concentrations.

Interesterified Palm Olein (IEPalm) and Interesterified Stearic Acid-Rich Fat Blend (IEStear) Have No Adverse Effects on Insulin Resistance: A Randomized Control Trial

Chemically-interesterified (CIE) fats are trans-fat free and are increasingly being used as an alternative to hydrogenated oils for food manufacturing industries to optimize their products' characteristics and nutrient compositions. The metabolic effects of CIE fats on insulin activity, lipids, and adiposity in humans are not well established. We investigated the effects of CIE fats rich in palmitic (C16:0, IEPalm) and stearic (C18:0, IEStear) acids on insulin resistance, serum lipids, apolipoprotein concentrations, and adiposity, using C16:0-rich natural palm olein (NatPO) as the control. We designed a parallel, double-blind clinical trial. Three test fats were used to prepare daily snacks for consumption with a standard background diet over a period of 8 weeks by three groups of a total of 85 healthy, overweight adult volunteers. We measured the outcome variables at weeks 0, 6, and at the endpoint of 8. After 8 weeks, there was no significant difference in surrogate biomarkers of insulin resistance in any of the IE fat diets (IEPalm and IEStear) compared to the NatPO diet. The change in serum triacylglycerol concentrations was significantly lower with the IEStear diet, and the changes in serum leptin and body fat percentages were significantly lower in the NatPO-diet compared to the IEPalm diet. We conclude that diets containing C16:0 and C18:0-rich CIE fats do not affect markers of insulin resistance compared to a natural C16:0-rich fat (NatPO) diet. Higher amounts of saturated fatty acids (SFAs) and longer chain SFAs situated at the sn-1,3 position of the triacylglycerol (TAG) backbones resulted in less weight gain and lower changes in body fat percentage and leptin concentration to those observed in NatPO and IEStear.

Cocoa and Dark Chocolate Polyphenols: From Biology to Clinical Applications

It is well known that cocoa and dark chocolate possess polyphenols as major constituents whose dietary consumption has been associated to beneficial effects. In fact, cocoa and dark chocolate polyphenols exert antioxidant and anti-inflammatory activities switching on some important signaling pathways such as toll-like receptor 4/nuclear factor κB/signal transducer and activator of transcription. In particular, cocoa polyphenols induce release of nitric oxide (NO) through activation of endothelial NO synthase which, in turn, accounts for vasodilation and cardioprotective effects. In the light of the above described properties, a number of clinical trials based on the consumption of cocoa and dark chocolate have been conducted in healthy subjects as well as in different categories of patients, such as those affected by cardiovascular, neurological, intestinal, and metabolic pathologies. Even if data are not always concordant, modifications of biomarkers of disease are frequently associated to improvement of clinical manifestations. Quite interestingly, following cocoa and dark chocolate ingestion, cocoa polyphenols also modulate intestinal microbiota, thus leading to the growth of bacteria that trigger a tolerogenic anti-inflammatory pathway in the host. Finally, many evidences encourage the consumption of cocoa and dark chocolate by aged people for the recovery of the neurovascular unit.

Associations of Plasma Phospholipid SFAs with Total and Cause-Specific Mortality in Older Adults Differ According to SFA Chain Length

BACKGROUND

Not much is known about the relations of circulating saturated fatty acids (SFAs), which are influenced by both metabolic and dietary determinants, with total and cause-specific mortality.

OBJECTIVE

We examined the associations of plasma phospholipid SFAs with total and cause-specific mortality among 3941 older adults from the Cardiovascular Health Study, a population-based prospective study of adults aged ≥65 y who were followed from 1992 through 2011.

METHODS

The relations of total and cause-specific mortality with plasma phospholipid palmitic acid (16:0), stearic acid (18:0), arachidic acid (20:0), behenic acid (22:0), and lignoceric acid (24:0) were assessed using Cox proportional hazards models.

RESULTS

During 45,450 person-years of follow-up, 3134 deaths occurred. Higher concentrations of the plasma phospholipid SFAs 18:0, 22:0, and 24:0 were associated with a lower risk of total mortality [multivariable-adjusted HRs (95% CIs)] for the top compared with the bottom quintile: 0.85 (0.75, 0.95) for 18:0; 0.85 (0.75, 0.95) for 22:0; and 0.80 (0.71, 0.90) for 24:0. In contrast, plasma 16:0 concentrations in the highest quintile were associated with a higher risk of total mortality compared with concentrations in the lowest quintile [1.25 (1.11, 1.41)]. We also found no association of plasma phospholipid 20:0 with total mortality.

CONCLUSIONS

These findings suggest that the associations of plasma phospholipid SFAs with the risk of death differ according to SFA chain length and support future studies to better characterize the determinants of circulating SFAs and to explore the mechanisms underlying these relations.

CETP genotype and changes in lipid levels in response to weight-loss diet intervention in the POUNDS LOST and DIRECT randomized trials

Little is known about whether cholesteryl ester transfer protein (CETP) genetic variation may modify the effect of weight-loss diets varying in fat content on changes in lipid levels. We analyzed the interaction between the CETP variant rs3764261 and dietary interventions on changes in lipid levels among 732 overweight/obese adults from a 2 year randomized weight-loss trial [Preventing Overweight Using Novel Dietary Strategies (POUNDS LOST)], and replicated the findings in 171 overweight/obese adults from an independent 2 year weight-loss trial [Dietary Intervention Randomized Controlled Trial (DIRECT)]. In the POUNDS LOST, participants with the CETP rs3764261 CC genotype on the high-fat diet had larger increases in HDL cholesterol (P = 0.001) and decreases in triglycerides (P = 0.007) than those on the low-fat diet at 6 months, while no significant difference between these two diets was observed among participants carrying other genotypes. The gene-diet interactions on changes in HDL-cholesterol and tri-glyc-erides were replicated in the DIRECT (pooled P for interaction ≤ 0.01). Similar results on trajectory of changes in HDL cholesterol and triglycerides over the 2 year intervention were observed in both trials. Our study provides replicable evidence that individuals with the CETP rs3764261 CC genotype might derive greater effects on raising HDL cholesterol and lowering triglycerides by choosing a low-carbohydrate/high-fat weight-loss diet instead of a low-fat diet.

Stacking of a stearoyl-ACP thioesterase with a dual-silenced palmitoyl-ACP thioesterase and ∆12 fatty acid desaturase in transgenic soybean

Soybean (Glycine max (L.) Merr) is valued for both its protein and oil, whose seed is composed of 40% and 20% of each component, respectively. Given its high percentage of polyunsaturated fatty acids, linoleic acid and linolenic acid, soybean oil oxidative stability is relatively poor. Historically food processors have employed a partial hydrogenation process to soybean oil as a means to improve both the oxidative stability and functionality in end-use applications. However, the hydrogenation process leads to the formation of trans-fats, which are associated with negative cardiovascular health. As a means to circumvent the need for the hydrogenation process, genetic approaches are being pursued to improve oil quality in oilseeds. In this regard, we report here on the introduction of the mangosteen (Garcinia mangostana) stearoyl-ACP thioesterase into soybean and the subsequent stacking with an event that is dual-silenced in palmitoyl-ACP thioesterase and ∆12 fatty acid desaturase expression in a seed-specific fashion. Phenotypic analyses on transgenic soybean expressing the mangosteen stearoyl-ACP thioesterase revealed increases in seed stearic acid levels up to 17%. The subsequent stacked with a soybean event silenced in both palmitoyl-ACP thioesterase and ∆12 fatty acid desaturase activity, resulted in a seed lipid phenotype of approximately 11%-19% stearate and approximately 70% oleate. The oil profile created by the stack was maintained for four generations under greenhouse conditions and a fifth generation under a field environment. However, in generation six and seven under field conditions, the oleate levels decreased to 30%-40%, while the stearic level remained elevated.

Plasma phospholipid saturated fatty acids and incident atrial fibrillation: the Cardiovascular Health Study

BACKGROUND

Prior studies suggest that circulating fatty acids may influence the risk of atrial fibrillation (AF), but little is known about the associations of circulating saturated fatty acids with risk of AF.

METHODS AND RESULTS

The study population included 2899 participants from the Cardiovascular Health Study, a community-based longitudinal cohort of adults aged 65 years or older in the United States who were free of prevalent coronary heart disease and AF in 1992. Cox regression was used to assess the association of all the long-chain saturated fatty acids-palmitic acid (16:0), stearic acid (18:0), arachidic acid (20:0), behenic acid (22:0), and lignoceric acid (24:0)-with incident AF. During a median of 11.2 years of follow-up, 707 cases of incident AF occurred. After adjustment for other AF risk factors, higher levels of circulating 16:0 were associated with a higher risk of AF (hazard ratio comparing highest and lowest quartiles: 1.48; 95% CI: 1.18, 1.86). In contrast, higher levels of circulating 18:0, 20:0, 22:0, and 24:0 were each associated with a lower risk of AF. The hazard ratios (95% CI) for AF in the top and bottom quartiles were 0.76 (95% CI: 0.61, 0.95) for 18:0; 0.78 (95% CI: 0.63, 0.97) for 20:0; 0.62 (95% CI: 0.50, 0.78) for 22:0; and 0.68 (95% CI: 0.55, 0.85) for 24:0.

CONCLUSIONS

Results from this prospective cohort study of older adults demonstrate divergent associations of circulating 16:0 versus longer-chain saturated fatty acids with incident AF, highlighting the need to investigate both determinants of these levels and potential pathways of the observed differential risk.

Palm oil and blood lipid-related markers of cardiovascular disease: a systematic review and meta-analysis of dietary intervention trials

BACKGROUND

Palm oil (PO) may be an unhealthy fat because of its high saturated fatty acid content.

OBJECTIVE

The objective was to assess the effect of substituting PO for other primary dietary fats on blood lipid-related markers of coronary heart disease (CHD) and cardiovascular disease (CVD).

DESIGN

We performed a systematic review and meta-analysis of dietary intervention trials. Studies were eligible if they included original data comparing PO-rich diets with other fat-rich diets and analyzed at least one of the following CHD/CVD biomarkers: total cholesterol (TC), low-density lipoprotein (LDL) cholesterol, high-density lipoprotein (HDL) cholesterol, TC/HDL cholesterol, LDL cholesterol/HDL cholesterol, triacylglycerols, apolipoprotein A-I and B, very-low-density lipoprotein cholesterol, and lipoprotein(a).

RESULTS

Fifty-one studies were included. Intervention times ranged from 2 to 16 wk, and different fat substitutions ranged from 4% to 43%. Comparison of PO diets with diets rich in stearic acid, monounsaturated fatty acids (MUFAs), and polyunsaturated fatty acids (PUFAs) showed significantly higher TC, LDL cholesterol, apolipoprotein B, HDL cholesterol, and apolipoprotein A-I, whereas most of the same biomarkers were significantly lower when compared with diets rich in myristic/lauric acid. Comparison of PO-rich diets with diets rich in trans fatty acids showed significantly higher concentrations of HDL cholesterol and apolipoprotein A-I and significantly lower apolipoprotein B, triacylglycerols, and TC/HDL cholesterol. Stratified and meta-regression analyses showed that the higher concentrations of TC and LDL cholesterol, when PO was substituted for MUFAs and PUFAs, were not significant in young people and in subjects with diets with a lower percentage of energy from fat.

CONCLUSIONS

Both favorable and unfavorable changes in CHD/CVD risk markers occurred when PO was substituted for the primary dietary fats, whereas only favorable changes occurred when PO was substituted for trans fatty acids. Additional studies are needed to provide guidance for policymaking.

Plasma kinetics of chylomicron-like emulsion and lipid transfers to high-density lipoprotein (HDL) in lacto-ovo vegetarian and in omnivorous subjects

PURPOSE

Previously, it was showed that vegan diet improves the metabolism of triglyceride-rich lipoproteins by increasing the plasma clearance of atherogenic remnants. The aim of the current study was to investigate this metabolism in lacto-ovo vegetarians whose diet is less strict, allowing the ingestion of eggs and milk. Transfer of lipids to HDL, an important step in HDL metabolism, was tested in vitro.

METHODS

Eighteen lacto-ovo vegetarians and 29 omnivorous subjects, all eutrophic and normolipidemic, were intravenously injected with triglyceride-rich emulsions labeled with ¹⁴C-cholesterol oleate and ³H-triolein. Fractional clearance rates (FCR, in min⁻¹) were calculated from samples collected during 60 min. Lipid transfer to HDL was assayed by incubating plasma samples with a donor nanoemulsion labeled with radioactive lipids.

RESULTS

LDL cholesterol was lower in vegetarians than in omnivores (2.1 ± 0.8 and 2.7 ± 0.7 mmol/L, respectively, p < 0.05), but HDL cholesterol and triglycerides were equal. Cholesteryl ester FCR was greater in vegetarians than in omnivores (0.016 ± 0.012, 0.003 ± 0.003, p < 0.01), whereas triglyceride FCR was equal. Cholesteryl ester transfer to HDL was lower in vegetarians than in omnivores (2.7 ± 0.6, 3.5 ± 1.5 %, p < 0.05), but free cholesterol, triglyceride and phospholipid transfers and HDL size were equal.

CONCLUSION

Similarly to vegans, lacto-ovo vegetarian diet increases remnant removal, as indicated by cholesteryl oleate FCR, which may favor atherosclerosis prevention, and has the ability to change lipid transfer to HDL.

Metabolism of triglyceride-rich lipoproteins and transfer of lipids to high-density lipoproteins (HDL) in vegan and omnivore subjects

BACKGROUND AND AIMS

Vegan diet excludes all foodstuffs of animal origin and leads to cholesterol lowering and possibly reduction of cardiovascular disease risk. The aim was to investigate whether vegan diet improves the metabolic pathway of triglyceride-rich lipoproteins, consisting in lipoprotein lipolysis and removal from circulation of the resulting remnants and to verify whether the diet alters HDL metabolism by changing lipid transfers to this lipoprotein.

METHODS AND RESULTS

21 vegan and 29 omnivores eutrophic and normolipidemic subjects were intravenously injected triglyceride-rich emulsions labeled with (14)C-cholesterol oleate and (3)H-triolein: fractional clearance rates (FCR, in min(-1)) were calculated from samples collected during 60 min for radioactive counting. Lipid transfer to HDL was assayed by incubating plasma samples with a donor nanoemulsion labeled with radioactive lipids; % lipids transferred to HDL were quantified in supernatant after chemical precipitation of non-HDL fractions and nanoemulsion. Serum LDL cholesterol was lower in vegans than in omnivores (2.1 ± 0.8, 2.7 ± 0.7 mmol/L, respectively, p < 0,05), but HDL cholesterol and triglycerides were equal. Cholesteryl ester FCR was greater in vegans than in omnivores (0.016 ± 0.012, 0.003 ± 0.003, p < 0.01), whereas triglyceride FCR was equal (0.024 ± 0.014, 0.030 ± 0.016, N.S.). Cholesteryl ester transfer to HDL was lower in vegans than in omnivores (2.7 ± 0.6, 3.5 ± 1.5%, p < 0,05). Free-cholesterol, triglyceride and phospholipid transfer were equal, as well as HDL size.

CONCLUSION

Remnant removal from circulation, estimated by cholesteryl oleate FCR was faster in vegans, but the lipolysis process, estimated by triglyceride FCR was equal. Increased removal of atherogenic remnants and diminution of cholesteryl ester transfer may favor atherosclerosis prevention by vegan diet.

Effect of short-term low- and high-fat diets on low-density lipoprotein particle size in normolipidemic subjects

High-fat, low-carbohydrate diets have been shown to raise plasma cholesterol levels, an effect associated with the formation of large low-density lipoprotein (LDL) particles. However, the impact of dietary intervention on time-course changes in LDL particle size has not been investigated. To test whether a short-term dietary intervention affects LDL particle size, we conducted a randomized, double-blind, crossover study using an intensive dietary modification in 12 nonobese healthy men with normal plasma lipid profile. Participants were subjected to 2 isocaloric 3-day diets: high-fat diet (37% energy from fat and 50% from carbohydrates) and low-fat diet (25% energy from fat and 62% from carbohydrates). Plasma lipid levels and LDL particle size were assessed on fasting blood samples after 3 days of feeding on each diet. The LDL particles were characterized by polyacrylamide gradient gel electrophoresis. Compared with the low-fat diet, plasma cholesterol, LDL cholesterol, and high-density lipoprotein cholesterol were significantly increased (4.45 vs 4.78 mmol/L, P = .04; 2.48 vs 2.90 mmol/L, P = .005; and 1.29 vs 1.41 mmol/L, P = .005, respectively) following the 3-day high-fat diet. Plasma triglycerides and fasting apolipoprotein B-48 levels were significantly decreased after the high-fat diet compared with the low-fat diet (1.48 vs 1.01 mmol/L, P = .0003 and 9.6 vs 5.5 mg/L, P = .008, respectively). The high-fat diet was also associated with a significant increase in LDL particle size (255.0 vs 255.9 Å;P = .01) and a significant decrease in the proportion of small LDL particle (<255.0 Å) (50.7% vs 44.6%, P = .01). As compared with a low-fat diet, the cholesterol-raising effect of a high-fat diet is associated with the formation of large LDL particles after only 3 days of feeding.

Cocoa and chocolate in human health and disease

Cocoa contains more phenolic antioxidants than most foods. Flavonoids, including catechin, epicatechin, and procyanidins predominate in antioxidant activity. The tricyclic structure of the flavonoids determines antioxidant effects that scavenge reactive oxygen species, chelate Fe2+ and Cu+, inhibit enzymes, and upregulate antioxidant defenses. The epicatechin content of cocoa is primarily responsible for its favorable impact on vascular endothelium via its effect on both acute and chronic upregulation of nitric oxide production. Other cardiovascular effects are mediated through anti-inflammatory effects of cocoa polyphenols, and modulated through the activity of NF-κB. Antioxidant effects of cocoa may directly influence insulin resistance and, in turn, reduce risk for diabetes. Further, cocoa consumption may stimulate changes in redox-sensitive signaling pathways involved in gene expression and the immune response. Cocoa can protect nerves from injury and inflammation, protect the skin from oxidative damage from UV radiation in topical preparations, and have beneficial effects on satiety, cognitive function, and mood. As cocoa is predominantly consumed as energy-dense chocolate, potential detrimental effects of overconsumption exist, including increased risk of weight gain. Overall, research to date suggests that the benefits of moderate cocoa or dark chocolate consumption likely outweigh the risks.

Effect of saturated fatty acid-rich dietary vegetable oils on lipid profile, antioxidant enzymes and glucose tolerance in diabetic rats

OBJECTIVE

To study the effect of saturated fatty acid (SFA)-rich dietary vegetable oils on the lipid profile, endogenous antioxidant enzymes and glucose tolerance in type 2 diabetic rats.

MATERIALS AND METHODS

Type 2 diabetes was induced by administering streptozotocin (90 mg/kg, i.p.) in neonatal rats. Twenty-eight-day-old normal (N) and diabetic (D) male Wistar rats were fed for 45 days with a fat-enriched special diet (10%) prepared with coconut oil (CO) - lauric acid-rich SFA, palm oil (PO) - palmitic acid-rich SFA and groundnut oil (GNO) - control (N and D). Lipid profile, endogenous antioxidant enzymes and oral glucose tolerance tests were monitored.

RESULTS

D rats fed with CO (D + CO) exhibited a significant decrease in the total cholesterol and non-high-density lipoprotein cholesterol. Besides, they also showed a trend toward improving antioxidant enzymes and glucose tolerance as compared to the D + GNO group, whereas D + PO treatment aggravated the dyslipidemic condition while causing a significant decrease in the superoxide dismutase levels when compared to N rats fed with GNO (N + GNO). D + PO treatment also impaired the glucose tolerance when compared to N + GNO and D + GNO.

CONCLUSION

The type of FA in the dietary oil determines its deleterious or beneficial effects. Lauric acid present in CO may protect against diabetes-induced dyslipidemia.

Cardiovascular disease risk of dietary stearic acid compared with trans, other saturated, and unsaturated fatty acids: a systematic review

BACKGROUND

High stearic acid (STA) soybean oil is a trans-free, oxidatively stable, non-LDL-cholesterol-raising oil that can be used to replace trans fatty acids (TFAs) in solid fat applications.

OBJECTIVE

The objective was to assess the cardiovascular health effects of dietary STA compared with those of trans, other saturated, and unsaturated fatty acids.

DESIGN

We reviewed epidemiologic and clinical studies that evaluated the relation between STA and cardiovascular disease (CVD) risk factors, including plasma lipids and lipoproteins, hemostatic variables, and inflammatory markers.

RESULTS

In comparison with other saturated fatty acids, STA lowered LDL cholesterol, was neutral with respect to HDL cholesterol, and directionally lowered the ratio of total to HDL cholesterol. STA tended to raise LDL cholesterol, lower HDL cholesterol, and increase the ratio of total to HDL cholesterol in comparison with unsaturated fatty acids. In 2 of 4 studies, high-STA diets increased lipoprotein(a) in comparison with diets high in saturated fatty acids. Three studies showed increased plasma fibrinogen when dietary STA exceeded 9% of energy (the current 90th percentile of intake is 3.5%). Replacing industrial TFAs with STA might increase STA intake from 3.0% (current) to approximately 4% of energy and from 4% to 5% of energy at the 90th percentile. One-to-one substitution of STA for TFAs showed a decrease or no effect on LDL cholesterol, an increase or no effect on HDL cholesterol, and a decrease in the ratio of total to HDL cholesterol.

CONCLUSIONS

TFA intake should be reduced as much as possible because of its adverse effects on lipids and lipoproteins. The replacement of TFA with STA compared with other saturated fatty acids in foods that require solid fats beneficially affects LDL cholesterol, the primary target for CVD risk reduction; unsaturated fats are preferred for liquid fat applications. Research is needed to evaluate the effects of STA on emerging CVD risk markers such as fibrinogen and to understand the responses in different populations.

Effects of pistachios on cardiovascular disease risk factors and potential mechanisms of action: a dose-response study

BACKGROUND

Nut consumption lowers cardiovascular disease (CVD) risk. Studies are lacking about the effects of pistachios, a nutrient-dense nut, on CVD risk factors, dose-response relations, and lipid-lowering mechanisms.

OBJECTIVE

We evaluated the effects of 2 doses of pistachios, added to a lower-fat diet, on lipids and lipoproteins, apolipoprotein (apo)-defined lipoprotein subclasses, and plasma fatty acids. To investigate the mechanisms of action, we measured cholesteryl ester transfer protein and indexes of plasma stearoyl-CoA desaturase activity (SCD).

DESIGN

In a randomized crossover controlled-feeding study, 28 individuals with LDL cholesterol > or = 2.86 mmol/L consumed 3 isoenergetic diets for 4 wk each. Baseline measures were assessed after 2 wk of a typical Western diet. The experimental diets included a lower-fat control diet with no pistachios [25% total fat; 8% saturated fatty acids (SFAs), 9% monounsaturated fatty acids (MUFAs), and 5% polyunsaturated fatty acids (PUFAs)], 1 serving/d of a pistachio diet (1 PD; 10% of energy from pistachios; 30% total fat; 8% SFAs, 12% MUFAs, and 6% PUFAs), and 2 servings/d of a pistachio diet (2 PD; 20% of energy from pistachios; 34% total fat; 8% SFAs, 15% MUFAs, and 8% PUFAs).

RESULTS

The 2 PD decreased (P < 0.05 compared with the control diet) total cholesterol (-8%), LDL cholesterol (-11.6%), non-HDL cholesterol (-11%), apo B (-4%), apo B/apo A-I (-4%), and plasma SCD activity (-1%). The 1 PD and 2 PD, respectively, elicited a dose-dependent lowering (P < 0.05) of total cholesterol/HDL cholesterol (-1% and -8%), LDL cholesterol/HDL cholesterol (-3% and -11%), and non-HDL cholesterol/HDL cholesterol (-2% and -10%).

CONCLUSIONS

Inclusion of pistachios in a healthy diet beneficially affects CVD risk factors in a dose-dependent manner, which may reflect effects on SCD.

Interaction between dietary fat intake and the cholesterol ester transfer protein TaqIB polymorphism in relation to HDL-cholesterol concentrations among US diabetic men

BACKGROUND

A low plasma HDL-cholesterol concentration is a major characteristic of diabetic dyslipidemia. HDL concentrations are determined by both environmental factors and genetic factors. Cholesterol ester transfer protein (CETP) plays an important role in the regulation of HDL metabolism, and the TaqIB polymorphism of the CETP gene has been associated with elevated HDL concentrations.

OBJECTIVE

We examined the association between the CETP TaqIB polymorphism and plasma HDL concentrations and evaluated whether this association was modified by dietary fat intake.

DESIGN

We followed 780 diabetic men aged 40-75 y who participated in the Health Professionals Follow-Up Study since its initiation in 1986. The participants had confirmed type 2 diabetes and were free of cardiovascular disease at the time blood was drawn.

RESULTS

After adjustment for age, smoking, alcohol consumption, fasting status, hemoglobin A(1c), physical activity, total energy intake, and body mass index, HDL concentrations were significantly higher in men with the B2B2 or B1B2 genotype than in those with the B1B1 genotype (adjusted x +/- SE: 37.9 +/- 0.02, 40.3 +/- 0.01, and 42.6 +/- 0.02 mg/dL for B1B1, B1B2, and B2B2, respectively; P for trend = 0.0004). This inverse association of the B1 allele with plasma HDL concentrations existed for those with a high consumption of animal fat (P for interaction = 0.02), saturated fat (P for interaction = 0.02), and monounsaturated fat (P for interaction = 0.04).

CONCLUSION

These data confirmed a significant effect of the CETP Taq1 gene on HDL concentrations and suggested a potential interaction between the CETP TaqIB polymorphism and intake of dietary fat on plasma HDL concentration.

Personalized nutrition: nutritional genomics as a potential tool for targeted medical nutrition therapy

An emerging goal of medical nutrition therapy is to tailor dietary advice to an individual's genetic profile. In the United States and elsewhere, "nutrigenetic" services are available over the Internet without the direct involvement of a health care professional. Among the genetic variants most commonly assessed by these companies are those found in genes that influence cardiovascular disease risk. However, the interpretation of DNA-based data is complex. The goal of this paper is to carefully examine nutritional genomics as a potential tool for targeted medical nutrition therapy. The approach is to use heart health susceptibility genes and their common genetic variants as the model.

Decreasing dietary fat saturation lowers HDL-cholesterol and increases hepatic HDL binding in hamsters

In order to study the mechanism by which increasing unsaturation of dietary fat lowers HDL-cholesterol levels, we studied various measures of HDL metabolism in hamsters fed with fats with different degrees of saturation. Hamsters were fed on a cholesterol-enriched (1 g/kg) semipurified diet containing 200 g/kg of maize oil, olive oil, or palm oil for 9 weeks. Increasing saturation of dietary fat resulted in increasing concentrations of total plasma cholesterol (4·29 (SD 0·51), 5·30 (sd 0·67) and 5·58 (sd 0·76) mmol/l respectively,n12) and HDL-cholesterol (3·31 (sd 0·50), 3·91 (sd 0·12) and 3·97 (sd 0·43) mmol/l) and these concentrations were significantly higher (P< 0·05) in the palm-oil and olive-oil-fed hamsters compared with the maize-oil group. Total plasma triacylglycerol levels also increased with increasing fat saturation (1·01 (sd 0·59), 1·56 (sd 0·65) and 2·75 (sd 1·03) mmol/l) and were significantly higher (P< 0·05) in the palm-oil group compared with the olive-oil and maize-oil-fed hamsters. The three diets did not have differential effects on plasma activity levels of lecithin: cholesterol acyltransferase (LCAT) and cholesteryl ester transfer protein (CETP). Levels of phospholipid transfer protein (PLTP) tended to be higher with increasing fat saturation but this effect was not significant. The capacity of liver membranes to bind human HDL3was significantly higher (P< 0·05) in the hamsters fed with maize oil (810 (sd 100) ng HDL3protein/mg membrane protein,n4) compared with those fed on palm oil (655 (sd 56) ng/mg), whereas the olive-oil group had intermediate values (674 (sd 26) ng/mg). The affinity of HDL3for the binding sites was not affected by the type of dietary fat. Hepatic lipase (EC3.1.1.3) activity, measured in liver homogenates, increased with increasing fat saturation. We conclude that dietary maize oil, when compared with either olive oil or palm oil, may lower HDL-cholesterol concentrations by enhancing HDL binding to liver membranes.

Palmitic and stearic acids similarly affect plasma lipoprotein metabolism in cynomolgus monkeys fed diets with adequate levels of linoleic acid

This study was designed to evaluate whether the exchange of specific saturated fatty acids [SFA; palmitic acid (16:0) for stearic acid (18:0)] would differentially affect plasma lipids and lipoproteins, when diets contained the currently recommended levels of total SFA, monounsaturated fatty acids and polyunsaturated fatty acids (PUFA). Ten male cynomolgus monkeys were fed one of two purified diets (using a cross-over design) enriched either in 16:0 (palmitic acid diet) or 18:0 (stearic acid diet). Both diets provided 30% of energy as fat (SFA/monounsaturated fatty acid/PUFA: 1/1/1). The palmitic acid and stearic acid diets were based on palm oil or cocoa butter (59% and 50% of the total fat, respectively). By adding different amounts of sunflower, safflower and olive oils, an effective exchange of 16:0 for 18:0 of approximately 5% of energy was achieved with all other fatty acids being held constant. Monkeys were rotated through two 10-wk feeding periods, during which time plasma lipids and in vivo lipoprotein metabolism (following the simultaneous injection of (131)I-LDL and (125)I- HDL were evaluated). Plasma triacyglycerol (0.40 +/- 0.03 vs. 0.37 +/- 0.03 mmol/L), plasma total cholesterol (3.59 +/- 0.18 vs. 3.39 +/- 0.23 mmol/L), HDL cholesterol (1.60 +/- 0.16 vs 1.53 +/- 0.16 mmol/L) and non-HDL cholesterol (2.02 +/- 0.26 vs. 1.86 +/- 0.23 mmol/L) concentrations did not differ when monkeys consumed the palmitic acid and stearic acid diets, respectively. Plasma lipoprotein compositional analyses revealed a higher cholesteryl ester content in the VLDL fraction isolated after consumption of the stearic acid diet (P < 0.10), as well as a larger VLDL particle diameter (16.3 +/- 1.7 nm vs. 13.8 +/- 3.6 nm; P < 0.05). Kinetic analyses revealed no significant differences in LDL or HDL transport parameters. These data suggest that when incorporated into diets following current guidelines, containing adequate PUFA, an exchange of 16:0 for 18:0, representing approximately 11 g/(d.10.46 mJ) [ approximately 11 g/(d.2500 kcal)] does not affect the plasma lipid profile and has minor effects on lipoprotein composition. Whether a similar effect would occur in humans under comparable dietary conditions remains to be established.

Studies on effects of dietary fatty acids as related to their position on triglycerides

This article reviews published literature on how the stereospecific structure of dietary triglycerides may affect lipid metabolism in humans. Animal studies have shown enhanced absorption of fatty acids in the sn-2 position of dietary triglycerides. Increasing the level of the saturated fatty acid palmitic acid in the sn-2 position (e.g., by interesterification of the fat to randomize the positions of the fatty acids along the glycerol backbone) has been shown in rabbits to increase the atherogenic potential of the fat without impacting levels of blood lipids and lipoproteins. In contrast, enhancing the level of stearic acid in the sn-2 position has not been found to affect either atherogenic potential or levels of blood lipids and lipoproteins in rabbits. Fatty acids other than palmitic and stearic have not been studied systematically with respect to possible positional effects. A limited number of human studies have shown no significant effects of interesterified fats on blood lipid parameters. However, it is unknown whether modifying the stereospecific structure of dietary triglycerides would affect atherogenicity or other long-term health conditions in humans. It is possible that incorporation of palmitic acid into the sn-2 position of milk fat is beneficial to the human infant (as a source of energy for growth and development) but not to human adults. Additional research is needed to determine whether processes like interesterification, which can be used to alter physical parameters of dietary fats (e.g., melting characteristics), may result in favorable or unfavorable long-term effects in humans.

Regulation by long-chain fatty acids of the expression of cholesteryl ester transfer protein in HepG2 cells

Cholesteryl ester transfer protein (CETP) is an important determinant of lipoprotein function, especially high density lipoprotein (HDL) metabolism, and contributes to the regulation of plasma HDL levels. Since saturated and polyunsaturated fatty acids (FA) appear to influence the CETP activity differently, we decided to investigate the effects of FA on the expression of CETP mRNA in HepG2 cells using an RNA blot hybridization analysis. Long-chain FA (>18 carbons) at a 0.5 mM concentration were added to the medium and incubated with cells for 48 h at 37 degrees C under 5% CO2. After treatment with 0.5 mM arachidonic (AA), eicosapentaenoic (EPA), and docosahexaenoic acid (DHA), the levels of CETP mRNA were less than 50% of the control levels (AA, P = 0.0005; EPA, P < 0.01; DHA, P < 0.0001), with a corresponding significant decrease in the CETP mass. These results suggest that FA regulate the gene expression of CETP in HepG2 and this effect is dependent upon the degree of unsaturation of the acyl carbon chain in FA.

Plasma lipid transfer proteins, high-density lipoproteins, and reverse cholesterol transport

Cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP) are members of the lipid transfer/lipopolysaccharide binding protein gene family. Recently, the crystal structure of one of the members of the gene family, bactericidal permeability increasing protein, was solved, providing potential insights into the mechanisms of action of CETP and PLTP. These molecules contain intrinsic lipid binding sites and appear to act as carrier proteins that shuttle between lipoproteins to redistribute lipids. The phenotype of human CETP genetic deficiency states and CETP transgenic mice indicates that CETP plays a major role in the catabolism of high-density lipoprotein (HDL) cholesteryl esters and thereby influences the concentration, apolipoprotein content, and size of HDL particles in plasma. PLTP also appears to have an important role in determining HDL levels and speciation. Recent data indicate that genetic CETP deficiency is associates with an excess of coronary heart disease in humans, despite increased HDL levels. Also, CETP expression is anti-atherogenic in many mouse models, even while lowering HDL. These data tend to support the reverse cholesterol transport hypothesis, i.e., that anti-atherogenic properties of HDL are related to its role in reverse cholesterol transport. Recently, another key molecule involved in this pathway was identified, scavenger receptor BI; this mediates the selective uptake of HDL cholesteryl esters in the liver and thus constitutes a pathway of reverse cholesterol transport parallel to that mediated by CETP. Reflecting its role in reverse cholesterol transport, the CETP gene is up-regulated in peripheral tissues and liver in responses to dietary or endogenous hypercholesterolemia. An analysis of the CETP proximal promoter indicates that it contains sterol regulatory elements highly homologous to those present in 3-hydroxy-3-methylglutaryl-coenzyme A reductase; the CETP gene is transactivated by the binding of SREBP-1 to these elements. A challenge for the future will be the manipulation of components of the reverse cholesterol transport pathway, such as CETP, PLTP, or scavenger receptor BI for therapeutic benefit.

Effect of 6 dietary fatty acids on the postprandial lipid profile, plasma fatty acids, lipoprotein lipase, and cholesterol ester transfer activities in healthy young men

BACKGROUND

There is increasing evidence that postprandial triacylglycerol-rich lipoproteins may be related to atherogenic risk.

OBJECTIVE

The objective was to investigate the effect of individual fatty acid intakes on postprandial plasma lipoprotein triacylglycerol and cholesterol concentrations, plasma fatty acids, and preheparin lipoprotein lipase and cholesterol ester transfer protein (CETP) activities.

DESIGN

Six test fats high (approximately 43% by wt) in stearic acid, palmitic acid, palmitic + myristic acid, oleic acid, elaidic acid (trans 18:1), and linoleic acid were produced by interesterification. After having fasted for 12 h, 16 healthy young men were served the individual test fats incorporated into meals (1 g fat/kg body wt) in random order on different days separated by washout periods. Blood samples were drawn before and 2, 4, 6, and 8 h after the meals.

RESULTS

Different responses to the test-fat meals were observed for plasma lipoprotein triacylglycerol and cholesterol concentrations, plasma fatty acid concentrations, and lipoprotein lipase and CETP activities (diet x time interaction: 0.001 < P < 0.05). Intake of the long-chain saturated fatty acids stearic and palmitic acids resulted in a relatively lower lipemic response than did intake of the unsaturated fatty acids, probably because the saturated fatty acids were absorbed less and at a lower rate; therefore, the lipemic response took longer to return to postabsorptive values.

CONCLUSIONS

Fatty acid chain length and degree of saturation appear to affect the extent and duration of lipemia and affect hepatic output indirectly. These effects may not be mediated via effects on lipoprotein lipase and CETP activities.

Variants in the cholesterol ester transfer protein and lipoprotein lipase genes are predictors of plasma cholesterol response to dietary change

There are no definitive explanations as to why individuals with hypercholesterolemia, a major cardiovascular risk factor, respond differently to dietary change. Fifty five free-living individuals completed a double crossover trial with two dietary regimens, a high saturated fat diet (providing 21% energy from saturated fat and 3% energy from polyunsaturated fat) and a high polyunsaturated fat diet (providing 11% energy as saturated fat and 10% energy as polyunsaturated fat), each phase continuing for 4 weeks. Extensive genotyping and several measures of dietary compliance have provided further insights regarding the determinants of extent of cholesterol response to changes in the nature of dietary fat. Individuals with the CETP B1B1 genotype and the LPL X447+ allele showed an average 0. 44 (95% CI: 0.22, 0.66) and 0.45 (95% CI: 0.18, 0.72) mmol/l greater change in total cholesterol, respectively, than those with one or more CETP B2 allele or homozygous for the LPL S447 allele when comparing diets high and low in saturated fat. Indices of dietary compliance including changes in reported saturated and polyunsaturated fat intake and change in triglyceride linoleate were not significantly different between the CETP genotypes. Change in reported saturated (r=0.36, P=0.04) and polyunsaturated (r=0.22, P=0. 05) fat intake and change in triglyceride linoleate (reflecting polyunsaturated fat intake) (r=0.21, P=0.07), also predicted total cholesterol response to dietary fat changes. In multivariate analyses, variation in the cholesterol ester transfer protein and lipoprotein lipase genes predicted response independent of measures of dietary compliance, suggesting that these two genes are important determinants of variation in cholesterol response to dietary change in free-living individuals.

Low-fat and high-monounsaturated fatty acid diets decrease plasma cholesterol ester transfer protein concentrations in young, healthy, normolipemic men

BACKGROUND

Cholesterol ester transfer protein (CETP) mediates the transfer of cholesteryl esters from HDL to apolipoprotein (apo) B-containing lipoproteins. The possible atherogenic role of this protein is controversial. Diet may influence plasma CETP concentrations.

OBJECTIVE

The objective was to determine whether the changes in plasma lipids observed after consumption of 2 lipid-lowering diets are associated with changes in plasma CETP concentrations.

DESIGN

: We studied 41 healthy, normolipidemic men over 3 consecutive 4-wk dietary periods: a saturated fatty acid-rich diet (SFA diet: 38% fat, 20% saturated fat), a National Cholesterol Education Program Step I diet (NCEP Step I diet: 28% fat, 10% saturated fat), and a monounsaturated fatty acid-rich diet (MUFA diet: 38% fat, 22% monounsaturated fat). Cholesterol content (27.5 mg/MJ) was kept constant during the 3 periods. Plasma concentrations of total, LDL, and HDL cholesterol; triacylglycerol; apo A-I and B; and CETP were measured at the end of each dietary period.

RESULTS

Compared with the SFA diet, both lipid-lowering diets significantly decreased plasma total and LDL cholesterol, apo B, and CETP. Only the NCEP Step I diet lowered plasma HDL cholesterol. Positive, significant correlations were found between plasma CETP and total (r = 0.3868, P < 0.0001) and LDL (r = 0.4454, P < 0.0001) cholesterol and also between changes in CETP concentrations and those of total (r = 0.4543, P < 0.0001) and LDL (r = 0.4554, P < 0.0001) cholesterol.

CONCLUSIONS

The isoenergetic substitution of a high-saturated fatty acid diet with an NCEP Step I or a high-monounsaturated fatty acid diet decreases plasma CETP concentrations.

Bioanalysis of PUFA metabolism and lipid peroxidation in coronary atherosclerosis

Twenty eight men (age 34-77 years) who underwent an elective coronary angiography for coronary artery disease (CAD), were studied. They were divided into group A (luminal narrowing < 50%; n = 11) and group B (luminal narrowing > 50%; n = 17). Capillary gas chromatography was used for determination of fatty acids. Retinol and alpha-tocopherol were analyzed by reversed-phase high-performance liquid chromatography (HPLC), other parameters were determined spectrofluorometrically and spectrophotometrically. Severe coronary atherosclerosis in group B was associated with higher serum low density lipoprotein/high density lipoprotein (LDL/HDL) cholesterol ratio, triacylglycerols, and phospholipids (P < 0.05). Erythrocyte membrane fatty acids C14:0, C16:1 and C22:6n3 were significantly higher in group B (P < 0.05). We found significantly higher plasma polyunsaturated fatty acids (PUFA) C18:3n6 in group B, whereas plasma linoleic acid was not changed significantly. There was a significant increase of IDL-C18:0, LDL-C14:0 and HDL-C22:6n3 PUFA in group B. We conclude that disturbances in saturated fatty acids (SUFA) and PUFA metabolism are associated with coronary atherogenesis. Such abnormalities may include enhanced extrahepatic transport of C14:0 SUFA via LDL and its incorporation into cell membranes, and enhanced clearance of anti atherosclerotic C22:6n3 PUFA via serum HDL.

Variations in serum cholesteryl ester transfer and phospholipid transfer activities in healthy women and men consuming diets enriched in lauric, palmitic or oleic acids

Cholesteryl ester transfer protein (CETP) and phospholipid transfer protein (PLTP) activities were measured in sera from 32 normolipidemic women and men consuming diets enriched in lauric, palmitic, or oleic acids. Serum CETP activity, measured as the rate of radiolabeled cholesteryl esters transferred from HDL toward serum apo B-containing lipoproteins, was higher with the palmitic acid diet (25.1+/-2.5%) than with the lauric acid (23.7+/-2.4%) and the oleic acid (24.0+/-2.7%) diets (P = 0.0028 and 0.0283, respectively). CETP mass concentrations, as measured with an enzyme-linked immunosorbent assay were increased after the lauric acid diet (2.57+/-0.63 mg/l) and the palmitic acid diet (2.49+/-0.64 mg/l) as compared with the oleic acid diet (2.34+/-0.45 mg/l) (P = 0.0035 and 0.0249, respectively). In contrast with CETP, serum PLTP activity, as measured as the rate of radiolabeled phosphatidylcholine transferred from liposomes toward serum HDL, was significantly higher with the lauric acid diet (23.5+/2.6%) than with the palmitic acid diet (22.5+/-2.5%) (P = 0.0013), while no significant differences were noted when comparing the saturated diets versus the oleic acid diet (23.0+/-2.3%). No significant alterations in the mean apparent diameter of LDL, and in the relative proportions of individual HDL subpopulations were observed from one dietary period to another. Nevertheless, lipid transfer activities correlated significantly with the relative abundance of HDL2b, HDL2a, HDL3b, and HDL3c, with opposite tendencies being observed for cholesteryl ester transfer and phospholipid transfer activities. In general, serum CETP activity correlated negatively with HDL cholesterol, but positively with triglyceride concentrations after the dietary interventions, and the relations with serum lipids were just the opposite for PLTP activity. In addition, CETP and PLTP activities correlated negatively when subjects consumed the standardized diets (P < 0.05 in all cases), but not when subjects consumed their habitual diet. It is concluded that serum lipid transfer activities in normolipidemic subjects can be significantly affected by the fatty acid content of the diet, with differential effects on CETP and PLTP activities.

A high-stearic acid diet does not impair glucose tolerance and insulin sensitivity in healthy women

Results in epidemiological and experimental studies suggest that a diet rich in saturated fat may affect insulin sensitivity. However, no published data are available on the effect of stearic acid in this respect. Therefore, we examined the effects of a high-stearic acid diet and a high-oleic acid diet on glucose metabolism, serum lipids and lipoproteins, and blood coagulation factors in 15 healthy female subjects. Subjects followed the two experimental diets for 4 weeks according to a randomized crossover design. Both experimental diet periods were preceded by consumption of a baseline diet for 2 weeks. The diets provided 36% of energy (E%) as fat. In the experimental diets, 5 E% stearic or oleic acid was substituted for 5 E% of saturated fatty acids in the baseline diet. After the experimental diets, no differences were found in the insulin sensitivity index (mean+/-SEM, 5.4+/-1.9 v 5.2+/-1.6 x 10(-4) min(-1) x microU(-1) x mL(-1), nonsignificant [NS]), glucose effectiveness (0.026+/-0.006 v 0.026+/-0.003 min(-1), NS), or first-phase insulin reaction ([FPIR] 368+/-57 v 374+/-66 mU/L x min, NS). The concentration of serum lipids and lipoproteins and blood coagulation factors did not differ after the diet periods. In conclusion, a diet rich in stearic acid did not deteriorate glucose tolerance or insulin action in young healthy female subjects as compared with a diet rich in oleic acid.