Yearly attained adherence to Mediterranean diet and incidence of diabetes in a large randomized trial

BACKGROUND

Several large observational prospective studies have reported a protection by the traditional Mediterranean diet against type 2 diabetes, but none of them used yearly repeated measures of dietary intake. Repeated measurements of dietary intake are able to improve subject classification and to increase the quality of the assessed relationships in nutritional epidemiology. Beyond observational studies, randomized trials provide stronger causal evidence. In the context of a randomized trial of primary cardiovascular prevention, we assessed type 2 diabetes incidence according to yearly repeated measures of compliance with a nutritional intervention based on the traditional Mediterranean diet.

METHODS

PREDIMED (''PREvención con DIeta MEDiterránea'') was a Spanish trial including 7447 men and women at high cardiovascular risk. We assessed 3541 participants initially free of diabetes and originally randomized to 1 of 3 diets: low-fat diet (n = 1147, control group), Mediterranean diet supplemented with extra virgin olive (n = 1154) or Mediterranean diet supplemented with mixed nuts (n = 1240). As exposure we used actual adherence to Mediterranean diet (cumulative average), yearly assessed with the Mediterranean Diet Adherence Screener (scoring 0 to 14 points), and repeated up to 8 times (baseline and 7 consecutive follow-up years). This score was categorized into four groups: < 8, 8-< 10, 10- < 12, and 12-14 points. The outcome was new-onset type 2 diabetes.

RESULTS

Multivariable-adjusted hazard ratios from time-varying Cox models were 0.80 (95% confidence interval, 0.70-0.92) per + 2 points in Mediterranean Diet Adherence Screener (linear trend p = .001), and 0.46 (0.25-0.83) for the highest (12-14 points) versus the lowest (< 8) adherence. This inverse association was maintained after additionally adjusting for the randomized arm. Age- and sex-adjusted analysis of a validated plasma metabolomic signature of the Mediterranean Diet Adherence Screener (constituted of 67 metabolites) in a subset of 889 participants also supported these results.

CONCLUSIONS

Dietary intervention trials should quantify actual dietary adherence throughout the trial period to enhance the benefits and to assist results interpretation. A rapid dietary assessment tool, yearly repeated as a screener, was able to capture a strong inverse linear relationship between Mediterranean diet and type 2 diabetes. Trial registration ISRCTN35739639.

Naturally-occurring phytosterols in the usual diet influence cholesterol metabolism in healthy subjects

BACKGROUND AND AIMS

Modulation of cholesterol absorption is potentially an effective way of lowering blood cholesterol levels and decreasing inherent cardiovascular risk in the general population. It is well established that cholesterol absorption efficiency can be modified by the intake of foods enriched with gram-doses of phytosterols, but little is known about the effects of phytosterols in the usual diet, even though moderate doses have been reported to affect whole-body cholesterol metabolism. A way to indirectly measure cholesterol synthesis and absorption rates is by quantification of serum non-cholesterol sterols. The aim of this study was to investigate the role of naturally occurring phytosterol intake on cholesterol absorption and serum cholesterol concentrations in a Spanish free-living population.

METHODS AND RESULTS

A total of 85 healthy volunteers were studied regarding their dietary habits (using a validated food frequency questionnaire), lipid profile and surrogate markers of cholesterol metabolism. Subjects were classified into tertiles of total phytosterol intake, and differences in lipid profile and markers of cholesterol metabolism were assessed by multivariate linear regression models adjusted for various confounders. The estimated daily intake of phytosterols and cholesterol was 489 (median) and 513 (mean) mg, respectively. Both serum low-density lipoprotein (LDL)-cholesterol concentration and sitosterol-to-cholesterol ratio adjusted by sitosterol intake (a surrogate marker of intestinal cholesterol absorption) decreased significantly (p < 0.05, both) across tertiles of phytosterol intake.

CONCLUSION

Moderate doses of phytosterols in the habitual diet might have a protective effect on the lipid profile via decreasing cholesterol absorption.

Association of plasma markers of cholesterol homeostasis with metabolic syndrome components. A cross-sectional study

BACKGROUND AND AIMS

Increased plasma phytosterols, which reflect enhanced cholesterol absorption, have been related to an increased risk of cardiovascular disease (CVD). However, high CVD risk conditions, such as obesity, diabetes and the metabolic syndrome (MetS) have been associated with reduced cholesterol absorption. We investigated associations between plasma noncholesterol sterols and MetS components.

METHODS AND RESULTS

With a cross-sectional design, we related MetS components to plasma noncholesterol sterol-to-cholesterol ratios measured by gas chromatography in 674 dyslipidemic patients and 361 healthy subjects participating in a prospective cohort study. Plasma phytosterol-to-cholesterol ratios were inversely associated with all components of the MetS. In the dyslipidemic group, multivariable analyses showed that a 1-SD increase in sitosterol-to-cholesterol ratio was associated with a reduced risk for any MetS feature, ranging from 0.57 (95% CI, 0.45 to 0.71) for visceral adiposity to 0.82 (95% CI, 0.69 to 0.98) for high blood pressure. The risk of having MetS was nearly halved, with ORs of 0.49 (95% CI, 0.38 to 0.64) or 0.56 (95% CI, 0.44-0.70), depending on the definition. Results were opposed for plasma lathosterol, a marker of cholesterol synthesis. Most findings were reproduced in the healthy cohort. ApoE genotype was unrelated to plasma noncholesterol sterols.

CONCLUSION

In both dyslipidemic and healthy populations, MetS is associated with increased plasma lathosterol, a cholesterol synthesis marker, and decreased plasma sitosterol, a marker of cholesterol absorption. Elevated plasma phytosterols related to a lower frequency of cardiometabolic risk factors, suggesting that they are associated with a reduced CVD risk.

Crossover study of diets enriched with virgin olive oil, walnuts or almonds. Effects on lipids and other cardiovascular risk markers

BACKGROUND AND AIMS

Virgin olive oil (VOO) and nuts are basic components of the Mediterranean diet, a heart-healthy dietary pattern. Nuts have well known cholesterol lowering effects, while evidence is unclear for VOO. We designed a study in hypercholesterolemic patients to assess the effects on serum lipids and other intermediate markers of cardiovascular risk of replacing 40% of the fat in the background diet with VOO, walnuts or almonds.

METHODS AND RESULTS

After a 4 week run-in period with a healthy diet, eligible candidates were randomized into three diet sequences in a crossover design, with a common background diet enriched with VOO, walnuts or almonds, lasting 4 weeks each. Outcomes were changes of serum lipids and oxidation and inflammation markers, measured by standard methods. Plasma fatty acids were determined by gas chromatography to assess compliance. In 18 participants completing the study (9 women, mean age 56 y, BMI 25.7 kg/m(2)), LDL-cholesterol was reduced from baseline by 7.3%, 10.8% and 13.4% after the VOO, walnut and almond diets, respectively (P = 0.001, Friedman test). Total cholesterol and LDL/HDL ratios decreased in parallel. LDL-cholesterol decreases were greater than predicted from dietary fatty acid and cholesterol exchanges among diets. No changes of other lipid fractions, oxidation analytes or inflammatory biomarkers were observed. Plasma fatty acid changes after each diet sequence supported good compliance.

CONCLUSION

The results confirm the cholesterol lowering properties of nut-enriched diets. They also suggest that phenolic-rich VOO has a cholesterol lowering effect independently of its fatty acid content, which clearly deserves further study.

Biomarker assessment of the immunomodulator effect of atorvastatin in stable renal transplant recipients and hypercholesterolemic patients

BACKGROUND

HMG-CoA reductase inhibitors (statins) have effects beyond lipid lowering, including immunomodulatory and anti-inflammatory properties. Statins are frequently combined with immunosuppressive agents in transplant recipients to modulate the hyperlipidemic side effects of the immunosuppressants. However, the role of statins in the immunosuppressive response that is achieved in individual patients remains to be assessed.

OBJECTIVE

The aim of this study was to evaluate the immunomodulatory effect of atorvastatin given alone and in combined treatment with tacrolimus and mycophenolate mofetil.

STUDY DESIGN

Two patient groups were studied: renal transplant recipients receiving tacrolimus and mycophenolate mofetil therapy, and hypercholesterolemic patients (the control group). Fasting blood samples were taken from participants before and 1 month after atorvastatin treatment was started to study a small battery of biomarkers that are able to reflect the range of the effects of immunosuppressive therapy and atorvastatin.

SETTING

All patients in the study were enrolled at the Hospital Clinic of Barcelona.

PATIENTS

All patients enrolled in the study were candidates for treatment with atorvastatin because of high cholesterol levels. One group consisted of 25 stable renal transplant recipients with low-density lipoprotein (LDL) cholesterol levels above 100 mg/dL after 3 months of therapeutic lifestyle changes, according to the guidelines of the National Kidney Foundation - Kidney Disease Outcomes Quality Initiative. The other group included 25 hypercholesterolemic patients with LDL cholesterol levels above target values for the patients' overall risk, as derived from the National Cholesterol Education Program Adult Treatment Panel III criteria.

INTERVENTION

Atorvastatin (Lipitor®) treatment was started at a fixed dose of 20 mg daily.

MAIN OUTCOME MEASURE

The studied biomarkers were lymphocyte proliferation, intracellular adenosine triphosphate (ATP) synthesis in CD4+ T cells, intralymphocytary cytokine expression (interleukin [IL]-2, interferon [IFN]-γ), soluble cytokine production (IL-2, IFN-γ, IL-10, IL-17, and transforming growth factor-β) and regulatory T (T(reg)) cells.

RESULTS

Atorvastatin proved to be an immunomodulatory agent, significantly decreasing lymphocyte proliferation by 15% (p = 0.001), increasing ATP levels by 16% (p = 0.0004), and showing a trend toward increasing T(reg) cells in hypercholesterolemic patients (p = 0.09). In the renal transplant recipients, atorvastatin therapy did not modify any of the biomarkers of immunosuppression that were studied.

CONCLUSION

Atorvastatin showed immunoregulatory effects on T cells in hypercholesterolemic patients. These effects were absent in renal transplant recipients, suggesting that the beneficial effects of atorvastatin in this patient group do not relate to immunoregulation. Therefore, statin treatment cannot be considered as a means to reduce the dose of immunosuppressive agents.

Inverse association between serum phospholipid oleic acid and insulin resistance in subjects with primary dyslipidaemia

BACKGROUND & AIMS

Data on intake of oleic acid (OA) and insulin resistance (IR) are inconsistent. We investigated whether OA in serum phosphatidylcholine relates to surrogate measures of IR in dyslipidaemic subjects from a Mediterranean population.

METHODS

Cross-sectional study of 361 non-diabetic subjects (205 men, 156 women; mean age 44 and 46 y, respectively; BMI 25.7 kg/m(2)). IR was diagnosed by BMI and HOMA values using published criteria validated against the euglycemic clamp. Alternatively, IR was defined by the 75th percentile of HOMA-IR of our study population. The fatty acid composition of serum phosphatidylcholine was determined by gas-chromatography.

RESULTS

The mean (±SD) proportion of OA was 11.7 ± 2.0%. Ninety-two subjects (25.5%) had IR. By adjusted logistic regression, including the proportions of other fatty acids known to relate to IR, the odds ratios (OR) (95% confidence intervals) for IR were 0.75 (0.62-0.92) for 1% increase in OA and 0.84 (0.71-0.99) for 1% increase in linoleic acid. Other fatty acids were unrelated to IR. When using the alternate definition of IR, OA remained a significant predictor (0.80 [0.65-0.99]).

CONCLUSIONS

Higher phospholipid proportions of OA relate to less IR, suggesting an added benefit of increasing olive oil intake within the Mediterranean diet.

An NPC1L1 gene promoter variant is associated with autosomal dominant hypercholesterolemia

BACKGROUND AND AIMS

A substantial number of subjects with autosomal dominant hypercholesterolemia (ADH) do not have LDL receptor (LDLR) or apolipoprotein B (APOB) mutations. Some ADH subjects appear to hyperabsorb sterols from the intestine, thus we hypothesized that they could have variants of the Niemann-Pick C1-Like 1 gene (NPC1L1). NPC1L1 encodes a crucial protein involved in intestinal sterol absorption.

METHODS AND RESULTS

Four NPC1L1 variants (-133A>G, -18C>A, 1679C>G, 28650A>G) were analyzed in 271 (155 women and 116 men) ADH bearers without mutations in LDLR or APOB aged 30-70years and 274 (180 women and 94 men) control subjects aged 25-65years. The AC haplotype determined by the -133A>G and -18C>A variants was underrepresented in ADH subjects compared to controls (p=0.01). In the ADH group, cholesterol absorption/synthesis markers were significantly lower in AC homozygotes that in all others haplotypes. Electrophoretic mobility shift assay (EMSA) results revealed that the -133A-specific oligonucleotide produced a retarded band stronger than the -133G allele. Luciferase activity with NPC1L1 -133G variant was 2.5-fold higher than with the -133A variant.

CONCLUSION

The -133A>G polymorphism exerts a significant effect on NPC1L1 promoter activity. NPC1L1 promoter variants might explain in part the hypercholesterolemic phenotype of some subjects with nonLDLR/nonAPOB ADH.

Determination of atorvastatin and its metabolite ortho-hydroxyatorvastatin in human plasma by on-line anion-exchange solid-phase extraction and liquid chromatography tandem mass spectrometry

A rapid, sensitive, and specific method was developed and validated using liquid chromatography-tandem mass spectrometry for the simultaneous quantitation of atorvastatin (ATV) and its major metabolite ortho-hydroxyatorvastatin (o-HATV) in human plasma. The sample preparation involved a liquid-liquid extraction without chlorinated solvents and an on-line solid-phase extraction exploring the possibilities that anion exchange offers. The analytical method presented intraday and day-to-day variation below 10%; intraday and day-to-day accuracy stood between 94% and 105%; the limit of quantification was 0.1 ng/mL for ATV and 0.5 ng/mL for o-HATV; and the recovery was above 75% for both molecules. This method was applied successfully to quantitate ATV and o-HATV concentrations in an unstudied renal transplant recipient cohort treated with an immunosuppressive regime of tacrolimus and mycophenolic acid and a cohort of hypercholesterolemic patients included in the study as a control group. It can be used to evaluate patient adherence, drug-drug interactions, and pharmacokinetic/pharmacodynamic relationships. The results in our study showed that ATV and o-HATV levels in the renal transplant group were significantly increased (p < 0.001), compared to the hypercholesterolemic group.

Increased intestinal cholesterol absorption in autosomal dominant hypercholesterolemia and no mutations in the low-density lipoprotein receptor or apolipoprotein B genes

CONTEXT

Autosomal dominant hypercholesterolemia (ADH) is frequently caused by functional mutations in the low-density lipoprotein receptor (LDLR) or apolipoprotein B-100 (APOB) genes, but approximately 40% of ADH subjects disclose no such molecular defects, possibly pointing to alternative genetic mechanisms.

OBJECTIVE

Our objective was to test the hypothesis that increased intestinal cholesterol absorption might play a role in the lipid abnormalities of subjects with ADH without identified genetic defects.

DESIGN AND SETTING

This is a cross-sectional study of consecutive subjects with primary hyperlipidemia identified during an 18-month period in two lipid clinics.

STUDY SUBJECTS

A total of 52 subjects with a clinical diagnosis of ADH were examined for molecular defects in LDLR and APOB. No APOB defects were found. Functional LDLR mutations occurred in 31 (60%) subjects, who received a diagnosis of familial hypercholesterolemia (FH). Those for whom no mutations could be identified were labeled as non-FH ADH. In addition, 38 subjects with familial combined hyperlipidemia (FCH) and 45 normolipidemic control subjects were studied.

INTERVENTIONS

Interventions were diagnostic.

MAIN OUTCOME MEASURES

Serum noncholesterol sterols were used as markers for the efficiency of intestinal cholesterol absorption.

RESULTS

Adjusted campesterol to cholesterol ratios increased in the order non-FH ADH more than FH more than controls more than FCH, with mean values (95% confidence interval) in 10(2) mmol/mol cholesterol of 505 (424-600), 397 (345-458), 335 (294-382), and 284 (247-328), respectively. Thus, cholesterol absorption was lowest in FCH and highest in non-FH ADH.

CONCLUSIONS

Increased intestinal cholesterol absorption may partially explain the high cholesterol levels of non-FH ADH subjects. Serum noncholesterol sterols are a useful tool for the differential diagnosis of genetic hypercholesterolemias, especially FCH and ADH unrelated to LDLR or APOB defects.

Diastolic function impairment in alcoholics

BACKGROUND

Chronic excessive ethanol consumption exerts a deleterious effect on the myocardium. Although the effects of chronic alcoholism on systolic cardiac function are well known, diastolic involvement has been evaluated only partially. Therefore, we determined the presence of left ventricular diastolic impairment in chronic alcoholics and its relation with simultaneous systolic dysfunction. We also assessed the influence of ethanol consumption in diastolic impairment.

METHODS

Thirty-five alcoholics with cardiomyopathy (ejection fraction < or = 50%) and 77 alcoholics with normal systolic function (ejection fraction > 50%) were evaluated. Assessment of New York Heart Association functional class, history of ethanol intake, technetium-99m radionuclide angiocardiography, and bidimensional Doppler echocardiography with evaluation of systolic and diastolic left ventricular function were performed.

RESULTS

Diastolic function impairment was present in one third of the alcoholics without cardiomyopathy, compared with two thirds of the patients with cardiomyopathy (p < 0.01). A pseudonormalization phenomenon of diastolic function was observed in patients with more advanced systolic dysfunction (ejection fraction < 32%). The deterioration of the diastolic parameters correlated with ethanol consumption, regardless of age (r = 0.44, p < 0.001 for ratio of peak velocity of the transmitral flow in early diastole and peak velocity of atrial contraction flow, with lifetime dose of ethanol).

CONCLUSIONS

There seems to be a dose-dependent effect of ethanol on systolic and diastolic heart function. Diastolic function impairment is present in one third of alcoholics with normal systolic function and is even more frequent when systolic dysfunction coexists.

High ethanol intake and malnutrition in alcoholic cerebellar shrinkage

To determine the influence of chronic ethanol intake and nutritional status on cerebellar shrinkage in alcoholism, we studied 12 undernourished patients with acute Wernicke's encephalopathy (WE), 12 undernourished and 24 well-nourished asymptomatic chronic alcoholics, and 24 age-matched well-nourished controls, using morphometric analysis of MRI scans with volumetry of the cerebellum. Alcoholics reported a mean daily intake of ethanol of 177+/-8 g over a period of 27+/-1 years. Most undernourished alcoholics and half of the well-nourished alcoholics, compared to one-tenth of the controls, showed a significant reduction in cerebellar volume (p< or =0.01, both). Alcoholics with cerebellar shrinkage (n=33) were older (p=0.05) and tended to report greater daily ethanol intake than alcoholics without cerebellar shrinkage (n=15), although not significantly so (p=0.09). Cerebellar volume correlated negatively with age in controls and asymptomatic alcoholics (r> or =0.52, p< or =0.01, both), with a significantly greater shrinkage for age in the latter (p=0.003). Logistic regression analysis showed that malnutrition (OR 6.6 [95%CI 1.7-25.6], p=0.005) and a daily ethanol intake of more than 140 g over ten years (OR 6.1 [95%CI 1.8-20.5], p=0.003) were independently associated with the development of cerebellar shrinkage.

Acute ethanol treatment decreases intracellular calcium-ion transients in mouse single skeletal muscle fibres in vitro

Alcohol misuse frequently leads to muscle weakness, which may also occur in the setting of acute and chronic alcoholic myopathies. At the cellular level, ethanol has been found to interfere with signalling mechanisms in cardiac myocytes, skeletal myotubes, and smooth muscle cells. In this study, we focused on the effects of ethanol on the intracellular calcium ([Ca(2+)](i)) transients responsible for excitation-contraction (EC) coupling in isolated mouse skeletal fibres loaded with the fluorescent Ca(2+) indicator fura-2. Following electrical stimulation, ethanol caused a significant reversible dose-dependent reduction in [Ca(2+)](i) transient amplitude, already significant at 100 mM ethanol (P = 0.03), without modifying resting [Ca(2+)](i). Evaluating the potential loci for the effects of ethanol, we indirectly measured sarcolemmal Ca(2+) entry by monitoring Mn(2+)-quenching of intracellular fura-2 via the nitrendipine-sensitive Ca(2+) channels during electrical pacing. Ethanol at doses of 20 mM and greater caused a dose-dependent reduction in the rate of fura-2 quenching (all at P<0.05). Moreover, the intracellular pool of Ca(2+) releasable by caffeine was found to be reduced at a minimum of 300 mM ethanol (P = 0.05). We conclude that ethanol reduces the [Ca(2+)](i) transients underlying EC coupling in single mouse skeletal muscle fibres. This acute effect of ethanol was primarily due to an inhibitory effect of ethanol on sarcolemmal Ca(2+) influx via voltage-operated Ca(2+)-channels and, to a lesser extent, to a reduction in the Ca(2+) sarcoplasmic reticulum loading state. This inhibitory effect of ethanol may be implicated in the development of muscle weakness with alcohol consumption.

Ethanol decreases basal cytosolic-free calcium concentration in cultured skeletal muscle cells

We analysed the effect of ethanol on basal cytosolic-free calcium concentration ([Ca2+]i) in cultured rat myocytes. Ethanol caused a dose-dependent decrease of the resting [Ca2+]i. Removal of ethanol was followed by a transitory increase of [Ca2+]i above the basal level. In cells chronically exposed to ethanol, [Ca2+]i normalized to the previous level.