THE MEDITERRANEAN ZONE

Barry Sears introduced the idea of the Zone in a book 20 years ago, and has written about a dozen books further explaining the concept, of which this is the latest. Readers will be familiar with the benefits of the Mediterranean diet, and perhaps with specific studies of long-lived Greek islanders. The concept of the Zone may be less familiar as a 'dietary roadmap for reaching and maintaining a constant hormonal balance that allows the body to operate at peak efficiency.' It is a metabolic state of stable blood sugar that diminishes risks of many chronic health issues. The book also clarifies the genuine traditional Mediterranean diet, not the false one full of pasta, pizza and bread. This diet is anti-inflammatory and antioxidant with a particular emphasis on the role of polyphenols. Specifically, it consists of one third low-fat protein, and two thirds colourful non-starchy vegetables and small amounts of fruit - note that this excludes white carbohydrates, including potatoes, all of which create more inflammation and increase the glycaemic load of the meal. This process is repeated every five hours, either as a meal or a snack.

The key is to maintain a balance between the two phases of inflammation activated by hormones, which themselves are controlled by our diet - these key hormones can be unbalanced by diet, which has happened on a wide scale over the last 50 years due to the industrialisation of food associated with increases in obesity, the development of chronic disease at an earlier age and the acceleration of brain ageing. The author puts this schematically as increased diet-induced inflammation > increased obesity > increased diabetes > increased Alzheimer's, with a time delay as each process reaches critical mass. Even more seriously, it appears that changes in epigenetic markers due to diet can be passed on to the next generation, creating a cumulative effect. The good news is that this process can be reversed on an individual level, although it may take decades to do so collectively. The author goes on to explain the mechanics of inflammation as the real reason we gain weight, become ill and age at a faster rate. In this sense, Alzheimer's is an ageing of the brain. In order to control diet-induced inflammation, one has to control insulin and the levels of omega-6 fatty acids found in vegetable oils and processed foods. In addition, people are eating a great deal more high glycaemic load carbohydrates, thus increasing the secretion of insulin. At the same time, we have reduced our consumption of omega-3 fatty acids found, for instance, in fatty fish and fish oil. Moreover, we are generally consuming fewer polyphenols in terms of fruits and vegetables. It is this combination that has led us to our current crisis.

In further explaining the Zone, the author discusses how hormonal control is based on the balance of protein to glycaemic load at every meal, and the danger of the current standard Western diet in terms of a combination of excess omega-6 fatty acids coupled with high levels of insulin leading to increased oxidation throughout the body without adequate levels of polyphenols and of omega-3 fatty acids. The overall goal becomes a reduction in diet-induced inflammation. In contrast with much official advice, the author produces his own Mediterranean zone food pyramid with vegetables and fruit at the bottom, then low-fat protein, mono-unsaturated fats like olive oil and moderate amounts of grains and starches. He gives specific examples, advice and pages of recipes as well as a sample shopping list and a summary of basic rules (pp. 73-74). The good news, for some of us at least, is that both coffee and red wine contain good levels of polyphenols, as explained in the next section. Spices, especially coriander, as well as parsley, sage, rosemary and thyme contain very high levels. A further interesting implication is the association between decreased calorie consumption and longevity, which is elaborated in terms of the proposition that the key factor for steady energy is stable blood sugar level rather than calorie consumption as such. Perhaps the most interesting historical example of this is Luigi Cornaro, a 15th century Venetian nobleman who wrote his third anti-ageing book at the age of 95.

The next section explains the correlation between the industrialisation of food and the rise of diet-induced inflammation, which is not in fact due to any single factor, but rather to a combination. It was truly alarming to read that China now has 100 million diabetics. Advances in trans-generational epigenetics are now enabling us to understand the implications of the health timebomb. It is possible to lay down diet-induced epigenetic markers in the DNA, so that children born after 2000 are much more susceptible to obesity – hence 'the growth of the industrialisation of our food supply may be a driving force in an epigenetic shift in our genes that could be responsible for the epidemic rise of obesity, diabetes and eventually Alzheimer's.' (p. 159) However, as stated above, it is possible to reclaim our genetic future, but not without a major turnaround in our lifestyles and dietary preferences. This in turn has implications for medicine, which traditionally neglects diet, and perhaps for a health system based on maintaining wellness rather than treating the symptoms of chronic disease. The second half of the book is devoted to a more technical discussion of the central issues. The author's arguments make a great deal of sense to me and have real practical implications for all of us - we would be well advised to modify our diets in the direction he recommends, even if it is harder to go all the way.