After adopting the Mediterranean Diet – after all, it is the diet of the year – you might feel righteous and obligated to check your retirement planning. Surely, you will now live to be very old, indeed. Let’s step back and see if this confidence is justified.
The Mediterranean Diet is defined by a high intake of fresh fruit, vegetables, nuts, whole grains and olive oil, a moderate intake of fish and poultry, and low intakes of dairy products such as yogurt and cheese, with avoidance of red and processed meats and sweets. In many versions, a moderate dollop of wine is allowed. This diet is supposed to decrease the risk of both heart disease and Alzheimer’s disease, and prolong life.
Legend has it that Dr. Ancel Keys developed the idea of the Mediterranean Diet while on the island of Crete. Dr. Keys observed that well-fed Minnesota businessmen were dying of cardiovascular disease at an alarming rate, while their customers in post-war Europe were thriving. He developed the hypothesis that the culinary habits of the Mediterranean protected people from cardiovascular events (heart attack and stroke) and concluded that saturated fats increased cholesterol levels, a risk factor for increased death from cardiovascular disease.
His hypothesis was controversial, but he was the only one with data.
Beginning in 1958, he fielded the remarkable Seven Countries Study following over 12,000 men for 14 years. The findings from the study were simple and have guided medical recommendations for the past five decades. The risk of coronary heart disease and stroke correlated with cholesterol levels and hinted at the relationship between hypertension, coronary disease and stroke. These findings formed the foundation of modern cardiology and nutritional recommendations that are preached today.
But does the Mediterranean Diet, as promoted by Dr. Keys, decrease heart disease and dementia and prolong life? The answer is, somewhat. The PREDIMED study showed that patients at high risk for cardiovascular disease had fewer cardiac events and stroke if they followed the Mediterranean Diet. If you are at risk for cardiovascular disease, there is a strong rationale for changing your diet. The investigators in the PREDIMED study were expansive when defining cardiovascular risk, including patients with type 2 diabetes or patients who exhibited at least three risk factors of either smoking, hypertension, elevated low-density lipoprotein cholesterol levels, low high-density lipoprotein cholesterol levels, overweight or obesity, or a family history of premature coronary heart disease.
Many propose the Mediterranean Diet decreases the risk of Alzheimer’s disease. However, lowering the risk of dementia is more difficult to support, so let’s focus on cardiovascular disease and life-expectancy. As expected, life expectancy in the United States was two and half years short than life expectancy in Greece – the country that defines the Mediterranean Diet. However, the risk of dying from heart disease or stroke in the United States is 87 and 24 per 100,000 respectively; significantly less than Greece – 112 and 65 per 100,000. That is, the risk of dying from cardiovascular disease in the country that defined the Mediterranean Diet is 60 percent higher than a country dining on fast food! That makes no sense if everything we have been told of the Mediterranean Diet preventing death cardiovascular disease is true.
What is going on? To put it simply, it’s complicated! The most obvious confounders of life-expectancy are the influence of diabetes, obesity, smoking and the uniquely American causes of death from drug overdoses and gunshot wounds. At least twice as many citizens in the United States, suffer from diabetes and obesity compared to Greece while drug overdose, and deaths from shooting are exceedingly rare in Greece. Alas, the Greeks do smoke more than those of us in the United States, but that appears to be their riskiest behavior. Could it be that Americans have a shortened life expectancy due to obesity and other self-inflicted causes of death; that is, behavioral causes of disease and death, not diet induced causes of disease and death? Do not underestimate the effect of deaths on young Americans from drug overdoses or gunshot wounds. In the life-expectancy league tables, it takes five people living to 90 years old to make up for the loss of one 20 year old who dies from an opioid overdose!
An intriguing possibility to explain this conundrum is that it is not what we eat, but how we eat. In the United States, we are famous for eating between meals. Recently, it has been suggested that eating frequently promotes systemic inflammation and chronic disease due to the complex biology of the intestinal microbiome and food. That is, when we eat, the gut leaks to cause low-grade systemic inflammation. As the inflammatory burden goes up, the incidence of chronic disease increases. Greece, like many Mediterranean cultures, are very disciplined about between-meal snacking. For some of us in the United States, the waking hours are one continuous meal! Finally, maybe it is all that fiber in the Mediterranean Diet that is making the difference. Recently published data suggests that a high fiber diet is responsible for prolonged life and healthy aging.
Confused yet? I am! What is the take home message? In my opinion, with an emphasis on my opinion, there are a number of them. If you have an increased risk for heart disease, there is data to support the adoption of a Mediterranean Diet. If you are everyone else, the benefits of adopting the Mediterranean diet falls into the category of might help, won’t hurt. That is, no one can give you a promise that it will benefit you, but it certainly won’t hurt you. The final take-home message is that there is a great deal more to life expectancy than what we eat. So get your sleep, eat your vegetables, exercise regularly, don’t abuse drugs and stay away from guns.
About the author:
Raymond J. Tesi, M.D., is CEO of INmune Bio, an immunotherapy company developing treatments to reprogram the innate immune system to fight disease.