However, one thing has become abundantly clear to me: a long and disease free life is never dependent on just one thing.
This statement is made with the caveat that obvious detriments to health, such as consuming lethal poison or jumping off a perilous cliff, offer certain consequences. Nevertheless, when one removes from the list such immediate threats to continued living, it becomes crystal clear that a host of factors contribute to the life we live and the day we die.
Foremost, but often not close to the most important factor, is the role that genetics plays. This is the influence least under our control as we obviously have no role in choosing our parents. But numerous studies, and in particular, the Swedish Twin Studies (that began in the 1870's, involving tens of thousands of identical twins who happened to grow up separately with varying lifestyles who developed different diseases and died at vastly different ages), have demonstrated that genetics plays no more than a 15 to 30% role in our overall longevity and disease development. Of course, those born with Down's syndrome, hemophilia and other genetic disorders would argue otherwise and they would be right. But for most people, genetics at most represents a predisposition for diseases whose ultimate manifestations are under our control.
So what does matter? For one, but not alone, it is environmental factors. Which? That's the $64,000 question. Is it processed foods, gluten, pesticides, household chemicals, pollution, contamination, etc., or could it be some mix and match of all of them?
Anyone who tells you they know with certainty is either delusional or just flubbing.
The reason no one can tell you the absolute answer is that it is often different for different people. For example, there are smokers who live to 100 and others that die far earlier. Some obese individuals have heart attacks in his or her 30's while others survive into their 90's.
More importantly, no one can do better than hypothesize because the scientific method can never be applied to such a multivariate question. The gold standard of scientific inquiry into a population's health would require a double-blind, randomized controlled study where all confounding variables are controlled. Unless we could snugly place people in a bubble, we could never firmly establish a definitive working conclusion.
Nevertheless, scientists slog on trying to make sense of what they can. They can show a strong correlation between smoking and lung cancer, alcoholism and cirrhosis of the liver, obesity and heart disease, etc. What they can't do is tell you if you simply avoid or consume one particular food then your longevity is guaranteed to be positively or negatively impacted, respectively.
For example, I think there is a strong basis in science to call sugar a human poison, albeit a slow acting one. My patients are cautioned to avoid it and to go to great lengths to minimize their exposure to it. Nevertheless, I don't believe that avoiding sugar alone guarantees a long life.
I often tell my audiences that if they eat plenty of fruits and vegetables, nuts and beans and seeds, whole grains and wild fish--they are going to die. I suspect they expect a different conclusion than the one proffered, but it's the truth. Long before processed foods even existed, people died and some at relatively young ages from a myriad of other factors--infections foremost among them. Food allows you to live by providing essential nutrition, but it doesn't guarantee health. Healthy eating doesn't offer protection against many simple infections like chickenpox and viruses or more esoteric infections like tuberculosis and tetanus. These sometimes life-threatening ailments often depend on passing exposure to these pathogens.
So what else matters? The mind.
Many an otherwise healthy person has been befallen by stress, anxiety, depression or any other number of mental health issues. Such factors may have a genetic or familial disposition. Some may be purely situational. Sometimes it's both. The connection between the mind and body is well established. It facilitates innocuous placebos to work and allows real, measurable systemic diseases to develop in the absence of any other factors.
I have witnessed this first hand. Learning about my family member's cancer brought back my heartburn which I thought I had banished forever. No diagnostic medical test, and I've had plenty of them searching for a clinical reason, has shown any other identifiable cause for this phenomenon. I know it is because of stress. Despite eating, sleeping, and living well, I have struggled to control my own guttural reaction to difficult news. I know that I must learn to manage my reaction to difficult news and I strive everyday to naturally manage my stress to relieve my symptoms.
This is why I know that the complex human body forged over 150,000 years to it's current form, and millions of years earlier in prior forms, is at once and always will be a very vulnerable and fragile system, highly complicated and efficient-- a veritable miracle of nature subject to forces sometimes beyond our control.
Although many would have you believe by the titles of their books such as "Why We Get Fat" or "Wheat Belly" that your health depends on one thing, I will tell you that it's simply not true. No pill, prescription or supplement, no food described as super or otherwise, no exercise routine, done in the gym or in nature, will guarantee health. Alternatively, certain vices like smoking and excess alcohol, consumption of certain processed foods, a sedentary lifestyle, poor sleep, great stress, etc. while expected to have a detrimental effect on your health, don't always factor in your death.
Your health depends on a combination of factors that affect both your body and mind. Ignoring any of these factors shifts the odds against you for a long and healthy life.
But please take note, it's never one thing.