This Is One Of The Biggest Myths About Longevity
When new patients first arrive in my office, many are suffering from multiple diseases that we associate with "normal" aging. Oftentimes they are perplexed by their illness—they think they are already doing everything right to live a long, healthy life. But commonly the very things they think will keep them young are actually causing them to age more quickly. There are a lot of popular theories of aging out there, and many of them are flat-out wrong. Yet they are deeply ingrained in our culture and, in fact, may seem completely logical on the surface. I call these the Seven Deadly Myths of Aging, and it's time to debunk them once and for all. Here's one of the most common:
Myth: Growth hormones promote youthfulness and vitality.
Think, for a moment, of a poodle. A standard poodle typically lives to be about 10 years old. A miniature poodle or a Yorkshire terrier, on the other hand, can live to be about 20. Now consider the fact that a miniature poodle and a standard poodle have the exact same genes. The miniature version was simply bred over time to become smaller.
Indulge me in a quick sidetrack. Dog breeding actually began in medieval England, where only landed gentry were allowed to own large dogs. In secret, peasants bred large dogs down to a smaller size so they could afford to own dogs that didn't have to eat much and could catch vermin for food. Of course, the smaller the dog, the fewer calories it needs. So is it possible that small dogs live longer than their larger genetic twins simply because they consume fewer calories and are in essence calorie restricted?
It may sound strange, but I think this idea holds a lot of weight (no pun intended). Most of the people who live in the Blue Zones are far shorter than the average height. Think about this, too: It's well-established that women have lower rates of coronary heart disease than men and on average live about seven years longer. Women are also an average of 5 inches shorter than men. Of course, correlation doesn't prove causation, but consider this: An analysis of 1,700 deceased people found that men and women of the same height actually had the same average life span.
Yet somehow we as a society hold on to the belief that the taller we are, the better. I couldn't disagree more, and I personally find the fact that we're getting taller as a species to be pretty darn scary. Between the end of the 19th century and the beginning of the 20th century, the average heights of both men and women increased by 4 inches. To put it bluntly, this growth is overrated.
So why are we getting taller? There's no doubt that what and how much we eat plays a critical role. In societies where children consume large amounts of vegetables, they tend to be shorter in stature as adults and begin reproducing later in life than children who eat fewer vegetables. But when those populations switch to more animal and refined-grain sources of food, their growth rates and stature increase. For example, after Western food was introduced in Japan, the population grew significantly taller within just 15 years. Since the 1960s, people in India and Singapore have also been eating more processed Western food and have grown considerably taller, and their rate of coronary heart disease has shot up in step with their height.
One of the major downsides of constant growth is that it promotes early puberty, particularly menarche (a girl's first menstruation). The early humans' diet, which included cycles of growth and regression, prompted slow growth and late puberty. In 1900, the average age at which a girl began to menstruate was 18. Now it is much younger, with some girls maturing sexually as young as age 8. This very precocious puberty often causes concern for parents, even before they learn that early puberty is linked to a greater risk of breast cancer, heart disease, diabetes, and death from any cause.
The numbers don't lie. Studies of U.S. war veterans, deceased professional baseball players, and French men and women (an odd grouping of folks, but bear with me) all show an inverse relationship between height and longevity. Many studies also reveal a connection between height and cancer. In one study, rapid growth during adolescence resulted in an 80 percent increased risk of cancer 15 years later. Stop right now and read that statistic again—an 80 percent increased risk of cancer! Want another chilling fact? When I was in medical school in the 1970s, children's cancer wards contained only a handful of beds; now they occupy whole towers or even entire hospitals.
My colleagues conducting another study divided more than 22,000 healthy male doctors in the United States into five categories based on height and followed up with them 12 years later. Even after adjusting for the doctors' ages, the results indicated a positive association between height and the development of cancer. This is terrifying, but it makes sense since high IGF-1 levels, caused by mTOR sensing energy in the body, promotes cell growth. This includes growth of both the cells that help us grow tall and the cells that become cancerous. Our shorter ancestors didn't live in a 365-day growth cycle, so IGF-1 wasn't constantly being stimulated the way it is today.
Dr. Longo's studies have also profiled a group of people in Ecuador called the Larons (named after the researcher who originally studied them, Zvi Laron). The Larons, who have absent growth hormone receptors, are unable to make IGF-1. These short adults are free from cancer and diabetes, similar to another group with the same syndrome in Brazil. What's even more intriguing is when you block the IGF-1 receptor in mice, creating "Laron mice," they live 40 percent longer than normal mice. Restrict the calories these mice consume, and they live even longer, yet giving them growth hormone abolishes the longevity effect of calorie restriction. This confirms the need to maintain a low level of IGF-1 if cancer-free longevity is your goal; it certainly is mine! Another way to look at this is that if consuming sugars and animal proteins increases your IGF-1 level, then lessening your consumption of them generally (but at least periodically) is the way to go. In other words, periods of promoting regression by lessening food intake in general and sugars and animal proteins in particular not only regulate growth but are important for reducing your metabolic rate.
From the book The Longevity Paradox. Copyright © 2019 by Steven R. Gundry. Published on March 19, 2019, by Harper Wave, an imprint of HarperCollins Publishers. Reprinted by permission.