Saturday, November 28, 2015

Are Blue Zones Worth Paying Attention To?

Life in a Blue Zone
Life in a Blue Zone
Blue Zones are a concept being promoted by the company Blue Zones (surprise!). The basic premise is that they looked at longevity statistics around the world, and found several places where longevity is unusually high. They then looked at what things these places have in common, with the hopes of coming up with rules that can be applied in other places to increase average human life expectancy.

This sounds like a noble goal, but how useful is it in practice? Am I just being a big bringdown by questioning the value of the project?

The obvious first point to consider is that Blue Zones is a for-profit company, so we should at least be careful about assuming that they're acting in our best interest. This doesn't necessarily have to mean that they are sinister or imply malice on their part, but it's important to be aware that if they didn't come up with useful answers as a result of the project, they'd be out of business.

Now, on to the Blue Zones themselves. What are the regions that are considered Blue Zones?
  • Sardinia, Italy
  • Okinawa, Japan
  • Loma Linda, California
  • Nicoya Peninsula, Costa Rica
  • Ikaria, Greece
These places all have unusually high life expectancy. So we just see what they have in common, and that should tell us how to replicate the results elsewhere, right?

Sample Sizes

Not so fast. One important thing to consider first is sample size.

Say you were looking at the statistics of your country, and you wanted to see where the highest rate of, say, renal cancer was. You will almost certainly find that it's in some small town somewhere. Now, check the stats for where the lowest rate of renal cancer is. You will probably find that it, too, is in some other small town. One of these towns must be doing something really right, and one must be doing something really wrong, right?

Not at all. The problem is that whenever you have samples with a small number of components, it's very easy for luck to throw off the sample. In a small town, you only need a couple more or less cases of something to throw off the stats for the whole town, because the sample is so small. So a couple of extra cancer cases make it look like something is going on. In a big city, you'd need a lot more cases of something to affect the overall stat in a noticeable way.

Applying this knowledge to Blue Zones, we need to be careful if any of the locations has a small population. What do we find? Well, Ikaria has a population of only around 8000. Loma Linda is around 23000 people. Nicoya is around 25000. Okinawa and Sardinia, on the other hand, are both above one million people.

So of these five locations that everything is being based on, three have very small populations that could easily get skewed statistics. That doesn't mean that they do, of course, but it's not a good sign.

Transferable Traits

One big problem with the whole concept of Blue Zones is that when looking for the things that each location has in common, by necessity the researchers are only looking at traits that are transferable to another location. Since the very goal is to replicate the results elsewhere (and sell some books in the process), if it turned out that, say, high altitude was responsible for longer life expectancy, this would end up being ignored because you can't transfer that.

Or, noticing that several of these populations are quite small, what if the very fact of living in small villages rather than big, crowded cities is a major reason for longer lives? Again, you can't sell that as a solution, so it has to be ignored.

It could well be that many of the common traits being promoted are actually just coincidental and have no value in increasing longevity on average (assuming that there is even a genuine longevity increase in these places to begin with), and that the things that actually matter were completely overlooked.

Isolated Traits

Consider another issue, which is whether or not you need several traits working together to get the desired results. Can you just identify several things that these places have in common and assume that each one individually is useful? Maybe without several working together you get no results, or even worse, negative results? Imagine if you found, say, that drinking alcohol and living at a high altitude worked together to increase longevity, but just alcohol on its own actually decreased it? Well, you would now be exporting shorter life spans and bad advice!

And the even more interesting thing could be that there are common traits in these different places, but they need to be combined with some other thing to get the right results, but the identity of that other thing is actually different in each location, like in Loma Linda they eat lots of beans, while in Ikaria they bathe in hot water a lot. And if you do one of these things along with drinking alcohol, you live longer (let me be clear that this is just a hypothetical). Well, these wouldn't be identified by Blue Zones, and so once again you'd actually be exporting bad advice to others.

Quality of Life

Finally, there's the actual question of whether Blue Zones is even looking at the right thing. Longevity is obviously nice, all things being equal, but are all things equal? Living a long life is not the same as a life worth living, and most people would probably choose a shorter, happier life over a longer, more miserable one.

If living a year longer involved decades of eating bland food, or painful exercises, or being sedentary and expending as little energy as possible, etc, maybe that wouldn't be a worthwhile tradeoff for most people. Rather than looking for the places on Earth where people live the longest, perhaps we should be looking for the places on Earth where people are happiest, and try to replicate those results?