How the RealAge Test Was Born

couple using laptop

The best way to start talking about the RealAge Test is to talk about the studies that both inspired it and continue to serve as its backbone.

The idea behind RealAge came first from a journal article which showed that smokers lived, on average, 8 to 10 years less than non-smokers. For any given age, a smoker had the same risk of death from any cause of a nonsmoker about 8 years older than he/she was. This led my friend and colleague Dr. Michael Roizen to say to a patient that due to his smoking, he wasn’t 44, but actually 52, having prematurely aged his body. The very same patient, having gotten through his surgery safely and been motivated to quit smoking, came back to Dr. Roizen and asked if there were other medical conditions that could be evaluated the same way. Thus, the idea for RealAge was born.

Thousands of studies, and thousands of highly educated man-hours later, Dr. Roizen and I, with the help of several other experts, had created the science background for the first RealAge Test. But first we had to work out the mathematics to make our estimation of RealAge more sophisticated than the simple estimate we first used.

You see, the RealAge Test looks at many different factors which impact mortality. The most powerful are smoking, blood pressure and blood cholesterol, but we found many other factors that affect overall mortality. Many dietary factors, especially fat intake, had an effect, as did exercise. Eventually, we had about 65 factors we were confident had effects on RealAge. But we found quickly we couldn’t simply add up the effects of each factor – we were getting results which made no sense. We found somebody with a RealAge over 120, and the healthiest person we could imagine (I named him Mr. Perfect) had a negative RealAge – less risk of death than a newborn. We needed some help.

Working with a mathematician at the University of Chicago, we developed (and later patented) an algorithm which allows large numbers of risk factors to be considered together as a group, and to take into account the interactions between risk factors and the tendency of behaviors to covary. This algorithm was painstakingly developed over months, and initially required immense computer processing time for a single user. However, we overcame the technical difficulties and developed a working program in the late 1990s.

In 2009, it was clearly time to update the entire test, and I was pleased to come back to RealAge to help do so. Once again, the key place to start was the scientific research. This time, we found that many of the original factors we thought promising enough to include (for example, supplemental vitamins E and C) had not been confirmed to have health benefits. These were removed from the test entirely. On the other hand, several new factors (for example, dietary fruits and vegetables, and having health insurance) had recently been proven to have an independent effect on overall mortality and thus on RealAge. I came to visit Dr. Oz and his science team several times during the year to give them updates and solicit suggestions for new areas to evaluate.

The requirements for a study to be included in the RealAge Test are quite stringent. The study must be published in a reputable, peer-reviewed scientific or medical journal, such as The New England Journal of Medicine, Annals of Internal Medicine, or JAMA. At least three confirmatory studies need to be published. Furthermore, each study was assigned a quality score by our team, based on the strength of the study. I personally read and reviewed over 500 trials which were included as primary and secondary sources for the current version of the RealAge Test. The vast majority of these studies have been published since 2000. In fact, we have been able to update the new RealAge Test with information from studies published in 2013.

Perhaps, most importantly, the study needs to pass a critical test: Do the results of the study change the way medicine is being practiced? These studies don’t happen often, but when they do, we immediately adjust the test. For interventions on healthy people, the evidence has to be solid enough that the scientific team is willing to change our own behavior (for example, I now take vitamin D supplements).

In the next few weeks, I’ll be talking a little bit more about what are the important factors in the RealAge Test to help people feel younger and live longer. But for right now – go take the test, if you haven’t.  Check it out at