Over the last two centuries, extraordinary progress in medicine, hygiene and technology gave us the gift of living much longer lives than our ancestors. But as things are right now, unfortunately, for many of us, and the people who care for us, living a longer life is less of a gift and more of a burden, since the years we have gained are often plagued by disease, mental illness, neurological symptoms, physical pain, or, what’s probably even worse, a lack of self-sufficiency. I think everybody agrees that our real goal is not just living a longer life, but rather, living a longer healthy life-span. And although both genetic and environmental factors determine our health and disease, we learn time and again that lifestyle and nutrition can go a very long way in helping us stay healthy and dramatically reduce risk of disease.
If we look at the statistics of the main causes of death in our post-industrialized countries, and we compare it with what they were a hundred or so years ago, we can observe very dramatic changes. At the beginning of the 20th century, the leading causes of death were acute, infectious diseases, like tuberculosis, pneumonia, diphtheria, diarrhea, or the flu. Today, these diseases are much less deadly and some of them have virtually disappeared, but they have made way to another kind of insidious killers: non-infectious, chronic, lifestyle related disease. These diseases are not caused by viruses or bacteria, are not transmissible, and are not as explosive: they develop slowly and silently, over the course of years or even decades, until it’s too late to reverse them. The number one cause of death today is cardiovascular disease, and its acute outcomes such as heart attacks. If we include cerebrovascular disease that leads to strokes, and type II diabetes that leads to cardiovascular complications, all conditions that are strictly interrelated, we account for the vast majority of deaths. Following closely we find malignant tumors, and the four leading cancer sites are lung cancer, breast cancer in women, prostate cancer in men, and colorectal cancer in both.
Chronic respiratory diseases and neurodegenerative diseases, such as Alzheimer’s disease, also claim a lot of lives. In this statistics, we refer to ‘cardiovascular disease” or ‘cancer’ as “causes” of death, but really, these are just the endpoints, the “diseases” that resulted in death. But what “really” caused the diseases?If we take a step back, we see that disease is the result of a combination of genetic and environmental factors. The genetic component is the natural predisposition that each of us has to develop any disease, and that is written in our genes. The environmental factors are all the external influences that increase or decrease the likelihood of developing a disease, such as being exposed to risk factors or engaging in protective behaviors. Some diseases are uniquely genetic, such as cystic fibrosis or sickle-cell anemia. Luckily, these diseases are very rare. Other causes of death are uniquely environmental, such as murders or accidents.
However, most diseases are a combination of both. And as it turns out, as far as the leading causes of death are concerned, such as cardiovascular disease and cancer, genetics only plays a minor part. These diseases are almost never “caused” by our genes. Our genes can determine a predisposition, but a predisposition is never a done deal. The last word belongs to our environment. With appropriate lifestyle and dietary choices, we can counterbalance detrimental genetic predispositions and ‘outsmart’ our genes. We know for example that overweight and obesity are key risk factors for cardiovascular disease, type II diabetes and many types of cancer.
And we also know that eating a balanced diet is the best strategy to maintain a healthy weight. High blood pressure, excess blood cholesterol, HDL to LDL unbalance, excess triglycerides, exaggerated platelet aggregation, a pro-inflammatory, pro-oxidant state, these are all widely recognized risk factors for cardiovascular disease, and they can all be controlled with diet. The risk of developing type II diabetes increases with frequent and excessive blood glucose peaks, hyperinsulinemia and development of insulin-resistance. And again, it is with diet that we can most effectively intervene. Constipation, alteration of gut bacteria composition, lack of antioxidants are important risk factors for colorectal cancer, and an adequate diet can fix all of these problems at once. We could go on and on listing similar connections that show how diet and nutrition are strongly linked to obesity, hypertension, atherosclerosis, cardiovascular disease, diabetes, cancer, osteoporosis, neurodegenerative disease, liver disease, and many others. We will explore some of these associations more in depth later in our course, but the underlying idea should be clear by now: a healthy, balanced diet has a tremendous potential to keep us healthy and minimize the risk of developing those chronic diseases that are the leading causes of death of our times.
We have learned so far that we can ask nutrition to help us prevent deficiencies and avoid excesses. But there’s a lot more that we can ask. Even without deficiencies and excesses, our dietary choices can promote health or promote disease. So the other major goal of nutrition, besides just preventing deficiencies and avoiding excesses, is much more ambitious: we can ask nutrition to promote optimal health and prevent disease. And now I’d like you to meet Mr X. Mr X is 42 years old, his father and grandfather both died of heart attack in their forties, his older brother already has three by-passes, and Mr X’s blood pressure is high, to the point he needs to take medications for it. And now I have a question for you. Do you think that there is some sort of inescapable divine curse that says that Mr X will have to die of cardiovascular disease? Let me now introduce you to Miss Y.
She is 33 years old, her grandmother died of breast cancer at age 39, and her mother also had breast cancer at age 46, but luckily it was diagnosed in time and she survived. Question. Do you think it is inevitably written in her destiny that Mrs Y will develop breast cancer? And here is Mrs Z. She is 52 years old. She has been overweight since age 16, and obese since age 27. She has gone through countless weight loss diets, some of them worked, but she was never able to keep her weight off for more than a few months. She eats less and exercise more than her friend Mrs W, who however doesn’t seem to ever gain a pound. Question: Should Mrs Z just give up and resign herself to the fact that no matter what she does she is condemned to forever be obese? And finally, please welcome Mr J. He is 48 years old. His father has always smoked two packs of cigarettes a day, but happily lived until age 94.
His mother was as sedentary as a sloth, yet she’s always been healthy and happily lived until age 91. Mr J himself is a smoker, has a sedentary lifestyle and never worried about his diet, but has been in good health and normal weight all his life. Question: Should Mr J keep doing what he is doing, since clearly he is genetically protected against disease? The answer to all of these four questions is a resounding NO. Our genes can certainly make us more or less susceptible to a disease, some of us are lucky, and our genetic protection against disease is able to offset some of our unhealthy lifestyle behaviors; some of us are less lucky, and just a little deviation from a healthy lifestyle results in detrimental consequences. However, for the vast majority of our leading causes of death, including cardiovascular disease, 95% of cancers, and type II diabetes, there is no genetic curse that will inevitably result in disease. The last word is always ours. Accumulating unhealthy lifestyle behaviors and psychosocial stresses, will dramatically enhance our risk of disease no matter how much our genes are favorable, and on the other hand, with our lifestyle and our behavior we can compensate a genetic disadvantage.