Skepticblog

In an SGU interview with Christopher Hitchens he commented that journalists tend to have a limited pallet of story themes from which they choose, and then they conform the story to the chosen theme. Stories always need to be about something, such as corporate greed or government malfeasance, so that is the story that is told – regardless of the pesky facts.

Bad science journalism works that way also. That is why we can joke about common cliches, such as “Missing Link Discovered,” “Scientists Baffled,” and “It turns out everything we thought we knew was wrong.”

One such science journalism meme is the “Elixir of Life” – a scientific “breakthrough” (there are no advances, only breakthroughs) that offers the hope of extended life or a panacea of sorts. These stories often follow another theme – taking an esoteric bit of research that is very preliminary and/or has very narrow implications, and then pulling from that research the most extreme speculative future application. That is why every basic life-science “breakthrough” could “potentially lead to a cure.”

To make matters worse, science press releases are increasingly engaging in this kind of rhetoric, and there seems to be a proliferation of lazy science journalists who are happy to pass along these press releases without further investigation.

All of this might explain why a small mouse study is being hailed in the press as the latest elixir of life discovery. The study involved giving mice either water or a diluted mixture of three branched-chain amino acids (leucine, isoleucine, and valine). They found that the mice fed the amino acids lived 12% longer than the control mice.

This is an interesting result. The researchers were testing this hypothesis because the same effect was found in yeast and they wanted to see if it could be replicated in a mammal. The theory is that increasing mitochondrial biogenesis can lead to extended lifespan, and these amino acids will lead to this increased biogenesis, which did occur in skeletal and cardiac myocytes (muscle cells), but not liver or fat cells.

What does this mean?  It is too early to say. First, this study needs to be replicated in order to confirm that it is a real effect and not a fluke, error, or result of some other variable that was not adequately controlled. For example, how sure are we that the control mice were not undernourished, even by a little, and the extra amino acids in the study mice just improved their nutritional intake?

Interpreting this study is not straightforward either. Amino acids are building blocks for proteins, and muscle is largely made of protein. So what this study is showing is that amino acids increased muscle building, but did not have the same effect in non-muscle tissue. Perhaps all it is showing is the well-known ability of protein supplements to enhance muscle building, and the greater muscle mass (including in cardiac tissue) lead to greater longevity. There may not be a separate effect on longevity.

Further, it is not clear how to (or if we can) extrapolate this research to larger mammals, or specifically to humans. Longevity studies in mice are always plagued by the fact that mice live for a few years in the lab, while we are trying to push human life expectancy past 80 years.

This, of course, has not stopped the most irresponsible of such extrapolation in some of the media. The Indian Express went so far as to report that body builder protein powders “adds 10yrs to life.” That's right, they went ahead and made a direct linear comparison between the mouse lifespan to the human lifespan.

Conclusion

This study is interesting, but it is one small study. It is not clear what it really means, if anything. It takes dozens of such studies, looking at a question from multiple angles and in multiple models, before scientists are reasonably sure they are onto a specific effect. And then the application of that effect needs to be tested in humans. We are a decade away, at least, from knowing if this study means anything for human longevity.

From a plausibility point of view, it is doubtful that anything as simple as just a dietary supplement with amino acids would have a huge impact of longevity. This is especially true in developed nations where access to protein is generally not limited, and not a limiting factor on biological function.

Human aging is complex. This does not mean it is an insurmountable problem (if you are inclined to see it as a problem), but with life-expectancy approaching 80 years, we have already picked the low-hanging fruit and have started to get diminishing returns from further improvements in lifestyle and health care. This is a further reason to be skeptical of claims that a simple dietary change could significantly extend longevity beyond 80.

This is why I would add “elixir of life” to the list of phrases in science reporting that would automatically trigger a skeptical response.