Obesity and diabetes mellitus are closely related metabolic diseases that have taken on epidemic proportions in the 21st century. Therefore, it is common for pathologies associated with obesity, such as cardiovascular diseases and cancer, to be the most common causes of death in developed countries. In this context, the most important factor in the prevention and treatment of these diseases is maintaining a healthy lifestyle based on a proper diet and suitable physical activity.
This is the reason that any hygiene or dietary measures that seek a healthy diet and a healthy lifestyle must always be present in any type of prevention and the first step to any treatment. Preventive efforts made in the primary care sector normally consist of “preventive” treatments based on drugs (lipid-lowering drugs, antihypertensive drugs, etc.), instead of first teaching people how to change their lifestyles. While these drugs are effective, the delays in primary prevention are quite pitiful because in addition to enormously increasing the pharmaceutical cost, the desired effectiveness is not reached because care usually comes too late. Moreover, while a “preventive” drug usually requires prior screening and is for a very narrow therapeutic target, hygiene and dietary measures can dispense with the screening and provide a wide range of advantages, resulting in an enormous global benefit for the people’s health.
The eating habits therefore play a crucial role in health maintenance, at both individual and population levels. In fact, diet and life habits in people’s youth and in middle age are key factors in maintaining good health until later stages in life. In this context, the analysis of the effects of the eating patterns is more important than the analysis of foods or nutrients, because it can be used to assess the synergistic effect of the different components in foods. Today, the Mediterranean diet is considered the healthiest eating model. In a systematic review of the effects of the 32 main dietary factors, it was concluded that the Mediterranean diet was the most effective dietary pattern against cardiovascular disease (Mente A et al. Arch Intern Med. 2009). In a recent meta-analysis of cohort studies assessing the effects of the Mediterranean diet, it was also found that the 2-point increase on a scale of adhesion to a conventional Mediterranean diet reduces overall mortality and the risk of suffering a cardiovascular disease by 10% (Martínez-González MA, et al. Curr Opin Lipid. 2014).
Nevertheless, dietary recommendations should be based on randomised nutritional intervention studies in which endpoints having a considerable impact on health (hard end-points) are assessed. Up until now, only one randomised clinical trial has been conducted in which the effect of a modified model of the Mediterranean diet (enriched with alpha-linolenic acid and a small amount of olive oil) versus a control diet in the secondary prevention of cardiovascular disease, called the Lyon Diet Heart Study, was assessed. It was found that the Mediterranean diet is associated with a distinct reduction of cardiovascular mortality and of the occurrence of cardiovascular complications in patients who have already suffered a myocardial infarction (De Lorgeril, et al. Circulation. 1999). Additionally, only one randomised clinical trial assessing the effects of the Mediterranean diet on the primary prevention of cardiovascular disease versus a low-fat diet, which has been the diet that was recommended up until a short time ago for the prevention of coronary heart disease, has been conducted. The PREDIMED study (PREvention with Mediterranean diet) was designed to assess long-term effects of a conventional Mediterranean diet without any calorie control on the occurrence of vascular complications in patients with a high vascular risk. 7447 participants were randomised into three intervention groups: Mediterranean diet supplemented with extra-virgin olive oil, Mediterranean diet supplemented with dried fruits and nuts and a low-fat diet (control group). After an average 4.8 years of follow-up, the two Mediterranean diet groups showed a 30% reduction in the relative risk of suffering cardiovascular complications, compared with the control group (Estruch R, et al. N Engl J Med. 2013). A 40% reduction in the risk of developing incident diabetes among the 3541 non-diabetic participants included in the study (Salas-Salvadó J., et al. Ann Intern Med. 2014), a 14% reduction in the prevalence of metabolic syndrome in the Mediterranean diet group supplemented with dried fruits and nuts (Salas-Salvadó J. et al. Arch Intern Med. 2008), and an almost 40% reduction in the risk of suffering atrial fibrillation in the Mediterranean diet group supplemented with extra-virgin olive oil (Martínez-González MA, et al. Circulation 2014) have also been observed. The analysis of intermediate vascular risk markers has demonstrated the benefits of the Mediterranean diet in connection with blood pressure, lipid profile, lipoprotein particles, inflammation, oxidative stress and carotid artery stenosis, as well as pro-atherogenic genes related to the cardiovascular complications and thrombosis (Ros E, et al. Adv Nutr. 2014). All this proves the usefulness of the Mediterranean diet in the primary prevention of cardiovascular disease. Nevertheless, the efficacy of an intervention with a low-calorie Mediterranean diet together with a physical activity programme and behavioural therapy in the prevention of cardiovascular disease, reduction of body weight and waist girth (visceral adiposity) and improved quality of life, as well as the mechanisms responsible for these effects, has yet to be proven.
To demonstrate the effects of the dietary patterns, foods and nutrients in the prevention and treatment of the chronic diseases and cancer, as well as the mechanisms responsible for their effects on health, to make recommendations to patients and the population in general, and to investigate strategies that allow following said recommendations.
See spanish website for furher information about research groups participating in this program.