Effect of an Indo-Mediterranean diet on progression of coronary artery disease in high risk patients (Indo-Mediterranean Diet Heart Study): a randomised single-blind trial

Olive oil, the Mediterranean diet, and arterial blood pressure: the Greek European Prospective Investigation into Cancer and Nutrition (EPIC) study

BACKGROUND

Diet has been reported to influence arterial blood pressure, and evidence indicates that the Mediterranean diet reduces cardiovascular mortality.

OBJECTIVE

The objective was to examine whether the Mediterranean diet, as an entity, and olive oil, in particular, reduce arterial blood pressure.

DESIGN

Arterial blood pressure and several sociodemographic, anthropometric, dietary, physical activity, and clinical variables were recorded at enrollment among participants in the Greek arm of the European Prospective Investigation into Cancer and Nutrition (EPIC) study. Of these participants, 20 343 had never received a diagnosis of hypertension and were included in an analysis in which systolic and diastolic blood pressure were regressed on the indicated possible predictors, including a 10-point score that reflects adherence to the Mediterranean diet and, alternatively, the score's individual components and olive oil.

RESULTS

The Mediterranean diet score was significantly inversely associated with both systolic and diastolic blood pressure. Intakes of olive oil, vegetables, and fruit were significantly inversely associated with both systolic and diastolic blood pressure, whereas cereals, meat and meat products, and ethanol intake were positively associated with arterial blood pressure. Mutual adjustment between olive oil and vegetables, which are frequently consumed together, indicated that olive oil has the dominant beneficial effect on arterial blood pressure in this population.

CONCLUSIONS

Adherence to the Mediterranean diet is inversely associated with arterial blood pressure, even though a beneficial component of the Mediterranean diet score-cereal intake-is positively associated with arterial blood pressure. Olive oil intake, per se, is inversely associated with both systolic and diastolic blood pressure.

Mediterranean diet and cancer risk

Various aspects of the Mediterranean diet are considered favourable with regard to cancer risk. These aspects were analysed using data from a series of case-control studies conducted in northern Italy between 1983 and 2001 on over 12,000 cases of 20 cancer sites and 10,000 controls. For most epithelial cancers, the risk decreased with increasing vegetable and fruit consumption, with odds ratios (OR) between 0.3 and 0.7 for the highest versus the lowest tertile. Subjects reporting frequent red meat intake showed ORs above unity for several common neoplasms. Conversely, fish (and consequently, n-3 fatty acids) tended to be another favourable dietary indicator. Wholegrain food intake was related to reduced risk of several types of cancer, particularly of the upper digestive tract, probably on account of its high fibre content. Fibres were in fact found to be protective with regard to colorectal and other selected cancers. In contrast to wholegrain, refined grain intake, and consequently glycaemic load, was associated with an increased risk of different types of cancer, including those of the upper digestive tract, colorectum, breast and endometrium. These results thus suggest that a low-risk diet for cancer entails increasing vegetables and fruit, reducing meat, but also refined carbohydrate consumption. Furthermore, olive oil and other unsaturated fats, which may be a unique common characteristic of the Mediterranean diet, should be preferred to animal and saturated fats. A score summarizing the major characteristics of the Mediterranean diet was inversely and consistently related to the risk of selected cancer sites. Regular consumption of pizza, one of the most typical Italian foods, showed a reduced risk of digestive tract cancers. Pizza could however simply be an indicator of a typical Italian diet.

Combination therapy of dyslipidemia in non-insulin-dependent diabetes mellitus and the metabolic syndrome

Non-insulin-dependent diabetes mellitus (NIDDM) and the metabolic syndrome separately and additively increase the risk for atherosclerotic cardiovascular disease. Considering the high cardiovascular risk associated with NIDDM and the metabolic syndrome, aggressive therapy of dyslipidemia with tailored combination therapy should be considered given informed consent and discussion of risks. In addition to statins, niacin, and fibrates, therapies shown to decrease the risk for atherosclerotic cardiovascular disease include omega-3 fatty acids, diet, exercise, and optimal blood pressure control with thiazides and blockers of the renin-angiotensin system. These therapies should also be considered to reduce the high cardiovascular risk associated with NIDDM and the metabolic syndrome.

Fruit and vegetable consumption is inversely associated with blood pressure in a Mediterranean population with a high vegetable-fat intake: the Seguimiento Universidad de Navarra (SUN) Study

There is evidence that a diet rich in fruit and vegetables reduces blood pressure (BP). Characteristically, the Mediterranean diet is rich in plant-derived foods and also in fat, but studies conducted in Mediterranean countries to relate diet to BP are scarce. We studied the association between fruit and vegetable consumption and BP in a cross-sectional analysis of 4393 participants in the Seguimiento Universidad de Navarra (SUN) Study, an ongoing dynamic cohort study in Spain. Diet was measured using a food-frequency questionnaire previously validated in Spain. Fat represented more than 37 % total energy intake. Subjects were considered to have undiagnosed hypertension if they reported systolic BP > or = 140 mmHg or diastolic BP > or = 90 mmHg, and not a medical diagnosis of hypertension. The adjusted prevalence odds ratio of undiagnosed hypertension (upper v. lowest quintile) was 0.58 (95 % CI 0.36, 0.91; P for trend 0.01) for vegetable consumption and 0.68 (95 % CI 0.43, 1.09; P for trend 0.10) for fruit consumption. Comparing those in the highest quintile of both fruit and vegetable consumption with those in the lowest quintile of both food groups, the prevalence odds ratio was 0.23 (95 % CI 0.10, 0.55; P = 0.001), after adjusting for risk factors for hypertension and other dietary exposures. In a Mediterranean population with an elevated fat consumption, a high fruit and vegetable intake is inversely associated with BP levels.

Atkins and other low-carbohydrate diets: hoax or an effective tool for weight loss?

CONTEXT

The Atkins diet books have sold more than 45 million copies over 40 years, and in the obesity epidemic this diet and accompanying Atkins food products are popular. The diet claims to be effective at producing weight loss despite ad-libitum consumption of fatty meat, butter, and other high-fat dairy products, restricting only the intake of carbohydrates to under 30 g a day. Low-carbohydrate diets have been regarded as fad diets, but recent research questions this view.

STARTING POINT

A systematic review of low-carbohydrate diets found that the weight loss achieved is associated with the duration of the diet and restriction of energy intake, but not with restriction of carbohydrates. Two groups have reported longer-term randomised studies that compared instruction in the low-carbohydrate diet with a low-fat calorie-reduced diet in obese patients (N Engl J Med 2003; 348: 2082-90; Ann Intern Med 2004; 140: 778-85). Both trials showed better weight loss on the low-carbohydrate diet after 6 months, but no difference after 12 months. WHERE NEXT?: The apparent paradox that ad-libitum intake of high-fat foods produces weight loss might be due to severe restriction of carbohydrate depleting glycogen stores, leading to excretion of bound water, the ketogenic nature of the diet being appetite suppressing, the high protein-content being highly satiating and reducing spontaneous food intake, or limited food choices leading to decreased energy intake. Long-term studies are needed to measure changes in nutritional status and body composition during the low-carbohydrate diet, and to assess fasting and postprandial cardiovascular risk factors and adverse effects. Without that information, low-carbohydrate diets cannot be recommended.

The traditional diet of Greece and cancer

The term 'Mediterranean diet', implying that all Mediterranean people have the same diet, is a misnomer. The countries around the Mediterranean basin have different diets, religions and cultures. Their diets differ in the amount of total fat, olive oil, type of meat, wine, milk, cheese, fruits and vegetables; and the rates of coronary heart disease and cancer, with the lower death rates and longer life expectancy occurring in Greece. The diet of Crete represents the traditional diet of Greece prior to 1960. Analyses of the dietary pattern of the diet of Crete shows a number of protective substances, such as selenium, glutathione, a balanced ratio of n-6/n-3 essential fatty acids (EFA), high amounts of fibre, antioxidants (especially resveratrol from wine and polyphenols from olive oil), vitamins E and C, some of which have been shown to be associated with lower risk of cancer, including cancer of the breast. Epidemiological studies and animal experiments indicate that n-3 fatty acids exert protective effects against some common cancers, especially cancers of the breast, colon and prostate. Many mechanisms are involved, including suppression of neoplastic transformation, cell growth inhibition, and enhanced apoptosis and anti-angiogenicity, through the inhibition of eicosanoid production from n-6 fatty acids; and suppression of cyclooxygenase 2 (COX-2), interleukin 1 (IL-1) and IL-6 gene expression by n-3 fatty acids. Recent intervention studies in breast cancer patients indicate that n-3 fatty acids, and docosahexaenoic acid (DHA) in particular, increase the response to chemopreventive agents. In patients with colorectal cancer, eicosapentaenoic acid (EPA) and DHA decrease cell proliferation, and modulate favourably the balance between colonic cell proliferation and apoptosis. These findings should serve as a strong incentive for the initiation of intervention trials that will test the effect of specific dietary patterns in the prevention and management of patients with cancer.

Alpha-linolenic acid and coronary heart disease

AIM

To summarize our present knowledge about vegetable omega-3 fatty acids.

DATA SYNTHESIS

Alpha-linolenic acid (ALA) is one of the two essential fatty acids in humans. Epidemiological studies and dietary trials strongly suggest that this fatty acid is important in relation with the pathogenesis (and prevention) of coronary heart disease. Like other n-3 fatty acids from marine origin, it may prevent cardiac arrhythmias and sudden cardiac death. The optimal dietary intake of alpha-linolenic acid seems to be about 2 g per day or 0.6 to 1% of total energy intake. Obtaining an optimal ratio of the two essential fatty acids, linoleic and alpha-linolenic acids--ie a ratio of less than 4 to 1 in the diet--is a major issue. The main sources of alpha-linolenic acid for the European population should be canola oil (and canola-oil based margarine if available), nuts (English walnut), ground linseeds and green leafy vegetables such as purslane.

CONCLUSIONS

Epidemiological studies and dietary trials in humans suggest that alpha-linolenic acid is a major cardio-protective nutrient.

Dietary alpha-linolenic acid is associated with reduced risk of fatal coronary heart disease, but increased prostate cancer risk: a meta-analysis

The objective of this meta-analysis was to estimate quantitatively the associations between intake of alpha-linolenic acid [ALA, the (n-3) fatty acid in vegetable oils], mortality from heart disease, and the occurrence of prostate cancer in observational studies. We identified 5 prospective cohort studies that reported intake of ALA and mortality from heart disease. We also reviewed data from 3 clinical trials on ALA intake and heart disease. In addition, we identified 9 cohort and case-control studies that reported on the association between ALA intake or blood levels and incidence or prevalence of prostate cancer. We combined risk estimates across studies using a random-effects model. High ALA intake was associated with reduced risk of fatal heart disease in prospective cohort studies (combined relative risk 0.79, 95% CI 0.60-1.04). Three open-label trials also indicated that ALA may protect against heart disease. However, epidemiologic studies also showed an increased risk of prostate cancer in men with a high intake or blood level of ALA (combined relative risk 1.70; 95% CI 1.12-2.58). This meta-analysis shows that consumption of ALA might reduce heart disease mortality. However, the association between high intake of ALA and prostate cancer is of concern and warrants further study.

Diet and risk of ischemic heart disease in India

BACKGROUND

Ischemic heart disease (IHD) is a leading cause of death in India. Dietary changes could reduce risk, but few studies have addressed the association between diet and IHD risk in India.

OBJECTIVE

The goal was to address the association between diet and IHD risk among Indians in New Delhi (northern India) and Bangalore (southern India).

DESIGN

We collected data from 350 cases of acute myocardial infarction and 700 controls matched on the basis of age, sex, and hospital as part of a hospital-based case-control study in 8 hospitals. Long-term dietary intake was assessed by using food-frequency questionnaires developed for New Delhi and Bangalore. We used conditional logistic regression to control for the matching factors and other predictors of risk.

RESULTS

We observed a significant and dose-dependent inverse association between vegetable intake and IHD risk. The inverse association was stronger for green leafy vegetables; in multivariate analysis, persons consuming a median of 3.5 servings/wk had a 67% lower relative risk (RR: 0.33; 95% CI: 0.17, 0.64; P for trend = 0.0001) than did those consuming 0.5 servings/wk. Controlling for other dietary covariates did not alter the association. Cereal intake was also associated with a lower risk. Use of mustard oil, which is rich in alpha-linolenic acid, was associated with a lower risk than was use of sunflower oil [for use in cooking: RR: 0.49 (95% CI: 0.24, 0.99); for use in frying, RR: 0.29 (95% CI: 0.13, 0.64)].

CONCLUSION

Diets rich in vegetables and use of mustard oil could contribute to the lower risk of IHD among Indians.

Flaxseed and cardiovascular risk

Flaxseed has recently gained attention in the area of cardiovascular disease primarily because it is the richest known source of both alpha-linolenic acid (ALA) and the phytoestrogen, lignans, as well as being a good source of soluble fiber. Human studies have shown that flaxseed can modestly reduce serum total and low-density lipoprotein cholesterol concentrations, reduce postprandial glucose absorption, decrease some markers of inflammation, and raise serum levels of the omega-3 fatty acids, ALA and eicosapentaenoic acid. Data on the antiplatelet, antioxidant, and hypotensive effects of flaxseed, however, are inconclusive. More research is needed to define the role of this functional food in reducing cardiovascular risk.

A walnut diet improves endothelial function in hypercholesterolemic subjects: a randomized crossover trial

BACKGROUND

Epidemiological studies suggest that nut intake decreases coronary artery disease (CAD) risk. Nuts have a cholesterol-lowering effect that partly explains this benefit. Endothelial dysfunction is associated with CAD and its risk factors and is reversed by antioxidants and marine n-3 fatty acids. Walnuts are a rich source of both antioxidants and alpha-linolenic acid, a plant n-3 fatty acid.

METHODS AND RESULTS

To test the hypothesis that walnut intake will reverse endothelial dysfunction, we randomized in a crossover design 21 hypercholesterolemic men and women to a cholesterol-lowering Mediterranean diet and a diet of similar energy and fat content in which walnuts replaced approximately 32% of the energy from monounsaturated fat. Participants followed each diet for 4 weeks. After each intervention, we obtained fasting blood and performed ultrasound measurements of brachial artery vasomotor function. Eighteen subjects completing the protocol had suitable ultrasound studies. Compared with the Mediterranean diet, the walnut diet improved endothelium-dependent vasodilation and reduced levels of vascular cell adhesion molecule-1 (P<0.05 for both). Endothelium-independent vasodilation and levels of intercellular adhesion molecule-1, C-reactive protein, homocysteine, and oxidation biomarkers were similar after each diet. The walnut diet significantly reduced total cholesterol (-4.4+/-7.4%) and LDL cholesterol (-6.4+/-10.0%) (P<0.05 for both). Cholesterol reductions correlated with increases of both dietary alpha-linolenic acid and LDL gamma-tocopherol content, and changes of endothelium-dependent vasodilation correlated with those of cholesterol-to-HDL ratios (P<0.05 for all).

CONCLUSIONS

Substituting walnuts for monounsaturated fat in a Mediterranean diet improves endothelium-dependent vasodilation in hypercholesterolemic subjects. This finding might explain the cardioprotective effect of nut intake beyond cholesterol lowering.

Omega-3 fatty acids and cardiovascular disease

PURPOSE OF REVIEW

Omega-3 fatty acids are gaining acceptance in the cardiovascular field. The present review describes the most recent studies and developments in the field.

RECENT FINDINGS

Marine omega-3 fatty acids, that is eicosapentaenoic and docosahexaenoic acids, prevent fatal myocardial infarction and sudden cardiac death by their antiarrhythmic effects and presumably also by their effect on infarct size, the latter mediated by plaque stabilization, improvements in endothelial function and other mechanisms. In contrast, a cardioprotective effect of alpha-linolenic acid, a plant-derived omega-3 fatty acid, remains to be clearly demonstrated in adequate intervention trials. Other forms of applications, like parenteral use or other indications, like in the psychiatric field, are currently being actively investigated.

SUMMARY

Eicosapentaenoic and docosahexaenoic acids, but not alpha-linolenic acid, prevent sudden death and other cardiovascular catastrophies, and have therefore been recently incorporated into the pertinent guidelines of European and American cardiologic societies.

What Can Intervention Studies Tell Us about the Relationship between Fruit and Vegetable Consumption and Weight Management?

Given the recent surge in obesity, effective dietary strategies for weight management are required. Because fruits and vegetables are high in water and fiber, incorporating them in the diet can reduce energy density, promote satiety, and decrease energy intake. Although few interventions have specifically addressed fruit and vegetable consumption, evidence suggests that coupling advice to increase intake of these foods with advice to decrease energy intake is a particularly effective strategy for weight management. This approach may facilitate weight loss because it emphasizes positive messages rather than negative, restrictive messages.

Cardiovascular disease resulting from a diet and lifestyle at odds with our Paleolithic genome: how to become a 21st-century hunter-gatherer

Our genetic make-up, shaped through millions of years of evolution, determines our nutritional and activity needs. Although the human genome has remained primarily unchanged since the agricultural revolution 10,000 years ago, our diet and lifestyle have become progressively more divergent from those of our ancient ancestors. Accumulating evidence suggests that this mismatch between our modern diet and lifestyle and our Paleolithic genome is playing a substantial role in the ongoing epidemics of obesity, hypertension, diabetes, and atherosclerotic cardiovascular disease. Until 500 generations ago, all humans consumed only wild and unprocessed food foraged and hunted from their environment. These circumstances provided a diet high in lean protein, polyunsaturated fats (especially omega-3 [omega-3] fatty acids), monounsaturated fats, fiber, vitamins, minerals, antioxidants, and other beneficial phytochemicals. Historical and anthropological studies show hunter-gatherers generally to be healthy, fit, and largely free of the degenerative cardiovascular diseases common in modern societies. This review outlines the essence of our hunter-gatherer genetic legacy and suggests practical steps to re-align our modern milieu with our ancient genome in an effort to improve cardiovascular health.

High omega-3 fatty acid content in alpine cheese: the basis for an alpine paradox

BACKGROUND

Alpha-linolenic acid (ALA) may protect from cardiovascular disease. Because fresh alpine grass contains high amounts of ALA, we hypothesized that the levels of omega-3 fatty acids would concentrate to nutritional relevance in the cheese of milk from cows with alpine grass feeding compared with cheese from silage and concentrate feeding; the newly available cheese produced from cows fed with linseed supplementation should contain even higher ALA concentrations.

METHODS AND RESULTS

Forty different cheeses were analyzed by gas chromatography for their fatty acid profile: (1) 12 from well-defined alpine regions around Gstaad, Switzerland; (2) 7 commercially available English cheddar cheeses; (3) 6 cheeses from cows fed with linseed supplementation; (4) 7 industrial-type Emmentals; and (5) 8 alpine cheeses with partial silage feeding. The alpine cheese contained 4 times more linolenic acid (C18:3omega-3) compared with cheddar, more total omega-3 fatty acids, and showed a significantly lower n-6:omega-3 ratio. Conjugated linoleic acid (C18:2 c9/t11) was 3-fold higher, whereas the amount of palmitic acid was 20% lower. The Emmental reached 40% of the ALA content compared with alpine cheese, and surprisingly, cheese from linseed-supplemented cows contained only 49% of that of the alpine cheese (P<0.001 for each trait in the 5 cheese groups).

CONCLUSIONS

Cheese made of milk from cows grazed on alpine pastures had a more favorable fatty acid profile than all other cheese types. Alpine cheese may be a relevant source of ALA and other cardioprotective fatty acids.

Adherence to a Mediterranean diet and survival in a Greek population

BACKGROUND

Adherence to a Mediterranean diet may improve longevity, but relevant data are limited.

METHODS

We conducted a population-based, prospective investigation involving 22,043 adults in Greece who completed an extensive, validated, food-frequency questionnaire at base line. Adherence to the traditional Mediterranean diet was assessed by a 10-point Mediterranean-diet scale that incorporated the salient characteristics of this diet (range of scores, 0 to 9, with higher scores indicating greater adherence). We used proportional-hazards regression to assess the relation between adherence to the Mediterranean diet and total mortality, as well as mortality due to coronary heart disease and mortality due to cancer, with adjustment for age, sex, body-mass index, physical-activity level, and other potential confounders.

RESULTS

During a median of 44 months of follow-up, there were 275 deaths. A higher degree of adherence to the Mediterranean diet was associated with a reduction in total mortality (adjusted hazard ratio for death associated with a two-point increment in the Mediterranean-diet score, 0.75 [95 percent confidence interval, 0.64 to 0.87]). An inverse association with greater adherence to this diet was evident for both death due to coronary heart disease (adjusted hazard ratio, 0.67 [95 percent confidence interval, 0.47 to 0.94]) and death due to cancer (adjusted hazard ratio, 0.76 [95 percent confidence interval, 0.59 to 0.98]). Associations between individual food groups contributing to the Mediterranean-diet score and total mortality were generally not significant.

CONCLUSIONS

Greater adherence to the traditional Mediterranean diet is associated with a significant reduction in total mortality.

Adipose tissue alpha-linolenic acid and nonfatal acute myocardial infarction in Costa Rica

BACKGROUND

Alpha-linolenic acid may protect against cardiovascular disease. We examined the association between adipose tissue alpha-linolenic acid and nonfatal acute myocardial infarction (MI) in a population-based case-control study in Costa Rica.

METHODS AND RESULTS

The 482 case patients with a first nonfatal acute MI and 482 population control subjects were matched by age, sex, and area of residence. Fatty acids were assessed by gas-liquid chromatography in adipose tissue samples collected from all subjects. ORs and 95% CIs were calculated from multivariate conditional logistic regression models. Subjects in the top quintiles of adipose tissue alpha-linolenic acid had a lower risk of MI than those in the lowest quintile: OR (95% CI), 1.00; 0.80 (0.52 to 1.24); 0.53 (0.34 to 0.82); 0.44 (0.28 to 0.67); and 0.37 (0.24 to 0.59); test for trend, P<0.0001. This association was strengthened after adjustment for established MI risk factors, including smoking, physical activity, income, and adipose tissue linoleic acid and trans fatty acids (OR for the top versus lowest quintile, 0.23; 95% CI, 0.10 to 0.50; test for trend, P<0.0001). Further adjustment for the intake of saturated fat, fiber, alcohol, and vitamin E did not change this association (OR for the top versus lowest quintile, 0.23; 95% CI, 0.10 to 0.55; test for trend, P<0.0001).

CONCLUSIONS

The inverse association observed between alpha-linolenic acid and nonfatal acute MI suggests that consumption of vegetable oils rich in alpha-linolenic acid confers important protection against cardiovascular disease.

What is the role of alpha-linolenic acid for mammals?

This review examines the data pertaining to an important and often underrated EFA, alpha-linolenic acid (ALA). It examines its sources, metabolism, and biological effects in various population studies, in vitro, animal, and human intervention studies. The main role of ALA was assumed to be as a precursor to the longer-chain n-3 PUFA, EPA and DHA, and particularly for supplying DHA for neural tissue. This paper reveals that the major metabolic route of ALA metabolism is beta-oxidation. Furthermore, ALA accumulates in specific sites in the body of mammals (carcass, adipose, and skin), and only a small proportion of the fed ALA is converted to DHA. There is some evidence that ALA may be involved with skin and fur function. There is continuing debate regarding whether ALA has actions of its own in relation to the cardiovascular system and neural function. Cardiovascular disease and cancer are two of the major burdens of disease in the 21st century, and emerging evidence suggests that diets containing ALA are associated with reductions in total deaths and sudden cardiac death. There may be aspects of the action and, more importantly, the metabolism of ALA that need to be elucidated, and these will help us understand the biological effects of this compound better. Additionally, we must not forget that ALA is part of the whole diet and should be seen in this context, not in isolation.