CHAPTER 1
The Med Diet in Healthcare and Disease Prevention

1. 1.1 Disease Prevention and Healthy Diets
   1. 1.1.1 Plant-based Diets
2. 1.2 The Mediterranean Diet
   1. 1.2.1 The Importance of Understanding How the Med Diet Works
3. 1.3 Achieving Dietary Change
4. 1.4 Healthcare Professionals
5. 1.5 Reasons for Optimism
6. 1.6 Conclusion
7. References

This chapter discusses the importance of placing greater emphasis on disease prevention, with particular reference to dietary advice around the Med diet. It also discusses how an understanding of how the Med diet works can shed light on how best to implement this diet.

1.1 DISEASE PREVENTION AND HEALTHY DIETS

The strain on health services from diseases that should be being prevented is now reaching crisis point. There is increasing support for the view that prevention is key to tackling the huge worldwide surge in chronic diseases. Prevention campaigns give people the knowledge, tools and support they need to better manage their health and are essential if we are to manage the epidemic of chronic diseases [1]. And yet of the £130 billion spent on the NHS every year (excluding COVID spending), 95% is still spent on treating illness, with just 5% going towards prevention [2]. A good example of the need for prevention is the great difficulty most people find in permanently losing weight once acquired, and hence the massive burden from obesity-related diseases [3].

FIGURE 1.1 Risk factors for disability in England for men and women combined. Risk is expressed as the proportion of all years lost to disability - disability-adjusted life-years (DALYs). Risk factors are calculated independently of each other and so cannot be summed together.

Source: [5] / with permission of Elsevier.

Poor diet has now overtaken smoking to become the top global contributor to morbidity and mortality from chronic diseases [4], including in many high-income countries (HICs) such as England [5] (Figure 1.1). The typical diet in HICs is the Western diet, characterised by excessive quantities of meat and other animal products, refined grains and highly processed foods (junk foods) - many of which fall within the recently described category of ultra-processed foods (UPFs). UPFs are made from highly refined ingredients and are designed to be hyperpalatable. This can make it difficult to restrict intake to acceptable levels, and so these products can incite binge eating [6]. Not surprisingly, there is now good evidence that consuming high levels of UPFs is strongly associated with an increased risk of obesity [7]. Consuming a Western diet frequently leads not only to overconsumption of calorie-rich macronutrients (carbohydrates and fat), but also to underconsumption of micronutrients (vitamins and minerals), phytochemicals and fibre. The result is consumers who are 'overfed and undernourished'.

1.1.1 Plant-Based Diets

To transition away from a Western diet, there is widespread consensus from the mainstream scientific community that a healthier diet is one based on 'minimally processed foods close to nature' [8]. In Michael Pollan's famous aphorism: 'Eat food. Not too much. Mostly plants'.1 Advice to eat mostly plant foods and to keep it natural has been a consistent message from nutrition scientists for many years.

Evidence suggests that plant-based dietary patterns, with their higher consumption of vegetables, fruits, legumes, nuts, whole grains, unsaturated oils, fish and lean meat or poultry (when meat is included), are associated with a decreased risk of all-cause mortality. These healthy patterns are low in red and processed meat, high-fat dairy and refined carbohydrates or sweets. Some of these dietary patterns also include alcoholic beverages in moderation [9].

1.2 THE MEDITERRANEAN DIET

The Mediterranean diet (Med diet) is one of several healthy, plant-based, semi-vegetarian dietary patterns that incorporate most of these recommendations. Others include the 'prudent' diet and the 'flexitarian' diet. The Med diet differs from these two patterns by explicitly recommending extra virgin olive oil (EVOO) as the main source of added fat and by recognising moderate amounts of alcohol consumption (mainly red wine) as being an acceptable accompaniment to the main meal of the day. Both of these foods are considered as healthful components of a Med diet.

The Med diet - also sometimes called the Mediterranean dietary pattern - often implies not just its food composition, but also how those foods are prepared and the social setting in which they are eaten. This is an important distinction between the Med diet and other healthy plant-based diets. As noted by Dr Antonio Trichopoulou, a leading authority on the Med diet, 'It would have been impossible to consume the high quantities of vegetables and legumes, which characterize the Mediterranean diet, were it not for olive oil that is traditionally used in the preparation of these dishes'. So although much of the guidance about implementing a Med diet relates to increasing various plant foods and restricting animal foods, there is evidence that a far greater emphasis should be given to food preparation and consumption [10]. Recommended consumption of fruit and vegetables in the Med diet is not just 'five a day', it is five a day the Med diet way.

1.2.1 The Importance of Understanding How the Med Diet Works

The increasing understanding of how the Med diet works is shedding light on why it is important to consider not only the foods themselves but also the way they are consumed. For example, consuming a Med diet is now known to suppress key early pathogenic stages associated with chronic diseases, such as oxidative stress, chronic low-grade inflammation and insulin resistance. Since oxidative stress and inflammation rise during the postprandial period, it is important to ensure that foods high in antioxidants are present during this postprandial period. A second example relates to the way a Western diet 'opposes' a Med diet. In contrast to the Med diet, the Western diet increases oxidative stress and inflammatory response. So this highlights the importance not only of enhancing adherence to a Med diet but also, at the same time, of reducing consumption of the proinflammatory foods associated with a Western diet. These examples show how a mechanistic understanding has important practical implications for the implementation of the Med diet.

1.3 ACHIEVING DIETARY CHANGE

A healthy diet is nutritious and sustaining. So it is unfortunate that so many people instead are choosing to eat a diet that is likely to substantially increase their personal risk of morbidity and mortality due to chronic disease. One explanation for this is that the general public still considerably underestimates the risks of developing a chronic disease that comes from eating a poor diet [11]. There are many reasons for this, such as the difficulty in public health campaigns of expressing health risk to the public in a meaningful way. Also, there is often scepticism about dietary advice. Although eating a healthy diet should be a simple message, disentangling the unhealthy aspects of eating from the overall diet has proven to be more complicated. Consumers are confused by the broad spectrum of views on which foods are permissible as part of a healthy diet. Also concerning are the perceived or actual contradictions in dietary information provided by the media. Much of the confusion is generated by the many vested interests competing to influence what we eat. Against this backdrop of confusion and lack of knowledge, the junk food industry is still able to play its hand with relative impunity.

Although the Med diet is widely perceived as tasty and healthy, there are many diverse reasons why people still shun it. There can be practical barriers, such as perceived cost and the perceived time and expertise needed for food preparation. Some of the practical barriers to understanding the benefits and ways of cooking are addressed in the many cookery books, websites and other resources on the Med diet. But providing accurate practical information may at best be only a small part of the optimal way of engaging people. Even when the risks from eating a poor diet are understood, there is still frequently a gap between what is known and what is done. Crucially, lack of implementation often arises because of deep-seated habits that make behaviour change difficult. Hence, it is often more important to support behaviour changes than it is to discuss specific facts about nutrition or food preparation.

1.4 HEALTHCARE PROFESSIONALS

Healthcare professionals are key players for widening implementation of the Med diet. However, some primary healthcare professionals are hesitant about offering dietary advice [12]. Some GPs, for example, may be unwilling to offer nutrition advice because they feel they lack the necessary knowledge to confidently discuss these issues with their patients [13]. Or they may feel that there are contradictions in existing recommendations...