Clinical trials: Taking a closer look at a recent longevity study

As the old Frank Sinatra song goes...
Here is the best part
Youll have a head start
If you are a mouse and very young at heart

Okay - it doesnt go exactly like that, of course. But a recent study (using mice) claims to provide some new information about how to reduce the effects of ageing by altering just one dietary habit.

If youre a mouse, this could be great news. But if youre a human, and can read, it actually brings up a question bigger than the one it answers.

Counting calories - but from where?
To be honest, when I sat down to write this e-alert I thought I might be on to something with valuable information. Tipped off by a news item released by Reuters Health, I was intrigued by the title: Cutting Calories May Keep Heart Young.

The concept of reducing calorie intake to increase your chances of longevity isnt new. But this was the first time Id seen it applied specifically to the heart. In a nutshell, here are the details:

A combined team of US researchers at the University of Wisconsin and the University of Alabama fed a uniform diet to a group of mice until they reached the age of 14 months - which for a mouse is considered middle-age. The mice were then split into two groups. The mice in one group were allowed to eat almost as much as they could, while those in the second group had their calorie intake reduced by 26%.

Sixteen months later, at the age of 30 months (equal to about 90 years in a human lifespan), heart tissue samples from the mice were analysed. The researchers found that the group fed the lower calorie diet had a 19% reduction in age-related genetic changes compared to the mice with the less-restricted diet. The low-cal mice also showed less DNA damage, a stronger immune system, and a suppression of programmed cell death, or apoptosis.

Even though the subjects in the study were mice, these results still seemed to have the potential to be promising. Nevertheless Ive read through enough of these to know how to read what wasnt there. What exactly were the mice eating? Were the diets identical? And how much more was one group eating than the other?

Obviously, the details of their diet would be a critical factor to determine what contributed to the results. So I went hunting and found a report of the study in the Proceedings of the National Academy of Sciences.

Whos hungry?
The mouse diet in the study turned out to be AIN-M semi-purified diet. In other words, its apparently standard mouse food designed to be used in clinical trials. But still, there was no information on exactly what was in the food. It could be anything. It could be the mouse equivalent of the Atkins diet. Or it could be a vegetarian diet. Or it could be gummi-bears - who knows? In a study about calorie intake, it certainly seems like an oversight to not identify the source of the calories.

Particularly because we know that the source of the calories, more than the quantity, can have a huge impact on heart health.

Coming up empty, I finally dug deep enough to discover this detail: The mice who were fed the restricted diet were fed a SPECIAL AIN-M semi-purified mouse food that was enriched with proteins, vitamins and minerals to avoid malnutrition. Is it just me, or does that one fact make the results of this study suspect?

No - its not just me.

Dont pass the AIN-M!
If the mice werent fed the same nutrients, how can you possibly hold the results of one group up against the other? And if the mice on the restricted diets received vitamins and minerals, its certainly possible that the positive effects they enjoyed from their diet came from the supplements as much (or more?) than the lower calorie intake.

Reuters and the other media outlets that reported this story arent outlining dietary guidelines for health-conscious mice. And they arent giving mice owners advice on how to make their pets live longer. The clear implication is that this study supports the hypothesis that lower calorie intake increases longevity and decreases the risk of heart problems in humans. And the casual reader of these reports, or headlines, would almost certainly come away with the idea that lowering calories, any calories, will add years to his life.

There may be something valid in the idea that managing calories could help us achieve better health as we age. But its not as simplistic as just lowering the numbers.

If this study tells the mice anything, I would say its to increase their intake of vitamins and minerals regardless of calorie intake. And, please pass the protein, vitamin and mineral enriched AIN-M semi-purified mouse food. Yum!