Effects of a French Mediterranean diet on heart transplant recipients with hypercholesterolemia

Modifying dietary patterns in cardiothoracic transplant patients to reduce cardiovascular risk: The AMEND-IT Trial

BACKGROUND

Cardiovascular disease (CVD) is common after cardiothoracic transplantation and causes substantial morbidity.

AIMS

To assess feasibility and potential effectiveness of dietary interventions to reduce CVD risk.

MATERIALS AND METHODS

In a pilot intervention, we recruited patients from a tertiary hospital and randomly allocated them to a Mediterranean or low-fat diet for 12 months. Feasibility was measured by patient participation, retention, and adherence. Changes in weight, body mass index (BMI), heart rate, blood pressure, glucose markers, and blood lipids were assessed using longitudinal generalized estimating equation regression models with 95% confidence intervals.

RESULTS

Of 56 heart and 60 lung transplant recipients, 52 (45%) consented, 41 were randomized, and 39 (95%) completed the study with good adherence to randomized diets. After 12 months, changes in many risk factors were seen in the Mediterranean and low-fat-diet groups, respectively, including mean BMI (-0.5 vs. 0.0 kg/m² ), systolic/diastolic blood pressure +0.5/+0.1 vs -4.4/-3.5 mmHg; fasting glucose -0.26 vs -0.27 mmol/L; total cholesterol -0.56 vs -0.40 mmol/L. Changes in BMI and systolic/diastolic blood pressure in 49 eligible patients who did not take part were +0.7 kg/m² and +2.5/+1.8 mmHg.

DISCUSSION

Dietary interventions in cardiothoracic transplant patients are feasible and potentially beneficial.

CONCLUSION

A definitive nutritional intervention study in these high-risk patients is warranted.

Adipose Tissue Fatty Acid Composition, Serum Lipids, and Serum α-Tocopherol in Continuous Ambulatory Peritoneal Dialysis Patients Living on the Island of Crete

Objective

A pilot study to explore diet-related atherogenic patterns in continuous ambulatory peritoneal dialysis (CAPD) patients on the island of Crete. Cretans are well known for their high olive consumption and low atherosclerotic heart disease mortality, in general.

Design

Case-control study.

Setting

This was a hospital-based study initiated in 1991. Catchment area was the island of Crete, Greece.

Participants

Seventeen patients admitted for treatment to the General State Hospital of Rethimnon. Controls were selected from the general population of the island and consisted of a random sample of 27 subjects from a total of 168 healthy subjects who visited the Preventive Medicine Clinic of the University Hospital for routine checkup. The control group was age- and sex-matched with patients. Both CAPD patients and controls had been residents of Crete for at least the last 10 years.

Main Outcome Measures

Adipose tissue was aspirated, and a 12-hour fasting blood sample was collected for determination of serum lipid parameters and serum α-tocopherol levels; dietary data from a 3-day recall were recorded.

Results

No significant differences between the two groups were observed with respect to the mean macronutrient intake. The mean levels of serum triglycerides ( p = 0.016) and serum α-tocopherol ( p = 0.001) were significantly higher in CAPD patients compared to controls. Mean levels of total serum cholesterol, high density lipoprotein (HDL) cholesterol, and low density lipoprotein (LDL) cholesterol were not significantly different. In CAPD patients the mean total percentage of monounsaturated fatty acids (MUFA) was significantly higher ( p = 0.006) than in controls. The mean total percentage of saturated fatty acids ( p = 0.004), along with the mean percentage of ω-6 ( p = 0.002), the mean value of the ratio ω-6/ω-3 ( p < 0.0001), and the percentage of linoleic acid ( p = 0.001) were significantly lower in CAPD patients than in the controls. Among subjects with higher levels of MUFA in the adipose tissue, the CAPD patients were twice as likely to have high serum α-tocopherol ( p < 0.001), and 2.6 times more likely to be in high risk of high total cholesterol (TC)/HDL ( p = 0.08) compared to the controls. However, CAPD patients with high levels of MUFA in the adipose tissue (above the average of 65%) were unlikely [odds ratio (OR) = 0.001, p < 0.001] to be at risk of high TC/HDL (above the average of 4.1), and maybe unlikely (OR = 0.08, but p = 0.1) to have low serum α-tocopherol, when compared with the CAPD patients with low levels of MUFA. CAPD patients with high TC/HDL are 0.15 times less likely ( p = 0.1) to have high levels of serum α-tocopherol compared to those with low TC/HDL.

Conclusion

Cretan CAPD patients demonstrate an interesting profile consisting of unexpectedly positive aspects when atherogenesis-related factors such as those of adipose tissue fatty acid composition, serum lipids, and serum antioxidant α-tocopherol are considered.

Elements of Mediterranean diet improve oxidative status in blood of kidney graft recipients

Patients were fully informed as to the study objectives and benefits, and provided written consent prior to enrolment. The study protocol was approved by the Committee on Human Research at the Pomeranian Medical University, Szczecin, Poland. An intensification of free-radical reactions may contribute to accelerated atherosclerosis in kidney graft recipients. We examined the effect of a Mediterranean-type diet (MD) on the oxidative status of the plasma and erythrocytes of kidney graft recipients. Two patient groups were formed: a study group consuming the MD diet and a control group with a low-fat diet. C-reactive protein levels in plasma, oleic acid C18: 1n-9 and linoleic acid C18: 2n-6 concentrations in triacyloglycerols were determined. To determine the oxidative status, we measured the concentrations of α-tocopherol in plasma, the content of thiobarbituric acid-reactive species (TBARS) in plasma and erythrocytes, and the activities of superoxide dismutase, catalase and glutathione peroxidase in erythrocytes. In the MD group, the activities of erythrocyte enzymes changed significantly: those of superoxide dismutase increased (P<0.001 after 6 months), catalase decreased (P<0.001 after 6 months) and glutathione peroxidase decreased (P<0.05 after 2 months). The oleic acid content of triacylglycerols was increased (P<0.006) whereas that of linoleic acid was decreased (P<0.00005), α-tocopherol levels remaining unchanged. TBARS in plasma were decreased after 6 months of MD (P<0.05). No significant correlations were observed between TBARS, oleic acid, linoleic acid and α-tocopherol levels in plasma. MD appears to protect the erythrocytes against the action of free radicals, as reflected in the modified activities of some enzymes regulating the oxidative status of these blood cells.

The use of neural networks in evaluation of the direction and dynamics of changes in lipid parameters in kidney transplant patients on the Mediterranean diet

OBJECTIVE

The objective of the study was to assess whether neural networks can be a tool useful in the evaluation of the effect of the Mediterranean diet (MD) on the direction and dynamics of selected parameters.

DESIGN

Randomized, prospective study.

SETTING

Outpatient Clinic of the Department of Nephrology, Transplantology, and Internal Medicine.

PATIENTS AND INTERVENTION

The study group consisted of 21 patients after kidney transplantation whose diet complied with the MD; the control group included 16 patients (also after transplantation) on a low-fat diet, isocaloric with the study diet.

MAIN OUTCOME MEASURES

Anthropometry, plasma lipids, chromatography of triacylglycerols and fatty acids, and activity of superoxide dismutase and catalase were measured in both groups. Statistical analysis was done with the SNN (Statistica Neural Networks) StatSoft software package.

RESULTS

The advantage of neural networks is the possibility of the dynamic presentation of a process taking place in a biological system. In the MD group in the first months of use of the diet, the cholesterol level was reduced only in the group of young and middle-aged patients. This tendency was not observed among elderly patients, among whom a small reduction of the total cholesterol level was noted only at the end of the observation period. In control group at the beginning of the observation, the plasma total cholesterol level was proportional to the patient's age. After 6 months, the total cholesterol increased in young patients and redacted in the group of elderly patients.

CONCLUSIONS

We concluded that the MD diet would be ideal for posttransplantation patients without serious pathologic dyslipidemia. In the case of patients with substantial dyslipidemia, appropriate pharmacologic treatment lowering proatherosclerotic lipid levels should be used in combination with the MD. Artificial neural networks (ANNs) were a useful tool in modeling biological parameters, showing dynamics of the studied interactions in a very detailed way. ANN is the most suitable method for investigations with many variables, interconnected nonlinearly; therefore, this method allows for a more general approach to biological problems. However, it should be noted that considerable data sets are required to obtain a satisfactory fit to the data. Moreover, to ensure the predictive power of this method for new cases, the representative database is indispensable. In spite of these demands, ANN is a prospective tool for reliable, quick assessments and predictions.

Scientific evidence of interventions using the Mediterranean diet: a systematic review

The Mediterranean Diet has been associated with greater longevity and quality of life in epidemiological studies, the majority being observational. The application of evidence-based medicine to the area of public health nutrition involves the necessity of developing clinical trials and systematic reviews to develop sound recommendations. The purpose of this study was to analyze and review the experimental studies on Mediterranean diet and disease prevention. A systematic review was made and a total of 43 articles corresponding to 35 different experimental studies were selected. Results were analyzed for the effects of the Mediterranean diet on lipoproteins, endothelial resistance, diabetes and antioxidative capacity, cardiovascular diseases, arthritis, cancer, body composition, and psychological function. The Mediterranean diet showed favorable effects on lipoprotein levels, endothelium vasodilatation, insulin resistance, metabolic syndrome, antioxidant capacity, myocardial and cardiovascular mortality, and cancer incidence in obese patients and in those with previous myocardial infarction. Results disclose the mechanisms of the Mediterranean diet in disease prevention, particularly in cardiovascular disease secondary prevention, but also emphasize the need to undertake experimental research and systematic reviews in the areas of primary prevention of cardiovascular disease, hypertension, diabetes, obesity, infectious diseases, age-related cognitive impairment, and cancer, among others. Interventions should use food scores or patterns to ascertain adherence to the Mediterranean diet. Further experimental research is needed to corroborate the benefits of the Mediterranean diet and the underlying mechanisms, and in this sense the methodology of the ongoing PREDIMED study is explained.

Insights into the pathogenesis and prevention of coronary artery disease

OBJECTIVE

To present information about risk factor clustering and the oxidation hypothesis of atherosclerosis and attempt to synthesize these facts into a clinically relevant approach to patients with or at risk for coronary artery disease (CAD).

MATERIAL AND METHODS

The total cholesterol level is a relatively weak marker for the risk of CAD. The levels of both high-density lipoprotein (HDL) cholesterol and remnants of triglyceride-rich lipoproteins and the inherent susceptibility of the low-density lipoprotein (LDL) particles to oxidative modification may be as important as the total or LDL cholesterol levels. LDL cholesterol must undergo oxidative modification by means of oxygen free radical processes before it becomes atherogenic. Patients with high levels of oxidative stress include those with risk factor clustering or insulin resistance (or both). Such patients are characterized by hypertension, truncal obesity, hypertriglyceridemia, depressed HDL cholesterol levels, and increased insulin levels. They also have increased levels of triglyceride-rich remnant lipoproteins and LDL particles that are characterized by their small dense nature and pronounced predisposition to oxidative modification.

RESULTS

Biologic antioxidants seem to be promising therapy for the prevention of atherogenesis. Although long-term prospective data are not yet available, vitamin E has been shown to be effective in both animal and human models in preventing LDL oxidation, and it may have a role in the prevention of CAD. A healthy diet of fresh fruits, vegetables, and whole grains is beneficial because it improves the lipid levels and provides high levels of natural antioxidants. The atherogenic potential of hydrogenated polyunsaturated fats is approximately equivalent to that of saturated fats. Monounsaturated fat is inherently resistant to oxidation and may be protective against CAD. Niacin may be effective in patients with clustered risk factors. It has been found to convert the easily oxidized small dense LDL pattern to the large buoyant oxidation-resistant particles. Hydroxymethylglutaryl-coenzyme A reductase inhibitors are well tolerated and highly effective in decreasing LDL cholesterol, but they are expensive. Estrogen has multiple potentially beneficial effects relative to cardiovascular disease.

CONCLUSION

Persons with or at high risk for CAD should be identified early and aggressively treated with a program that involves lifestyle changes, alterations in dietary intake, and pharmacologic therapy.