A Good Example of Failing to Control for Calorie Intake

Calorie restriction has a such a large impact on health that you almost have to disregard any study of health and longevity in laboratory animals that fails to control for it. Even mild differences in levels of calorie intake can swamp out the effects actually being studied. In humans calorie restriction doesn't have the same dramatic effect on longevity as it does in mice - we'd have noticed by now - but it does produce a dramatic improvement in measures of health. So it is probably past time that we look with suspicion on any study that fails to account for levels of calorie intake.

This work seems like a good example of the type, as the researchers examined dietary habits that most likely correlate strongly with overall calorie intake, but did not control for calorie intake in the analysis:

Study participants were adults aged 35 years or over within the Health Survey for England (HSE). Since 2001, HSE participants have been asked about fruit and vegetable consumption on the previous day. Cox regression was used to estimate hazard ratios for an association between fruit and vegetable consumption and all-cause, cancer and cardiovascular mortality, adjusting for age, sex, social class, education, body mass index, alcohol consumption and physical activity.

We found a strong inverse relationship between fruit and vegetable consumption and all-cause mortality which was stronger when deaths within a year of baseline were excluded and when fully adjusting for physical activity. Seriously ill individuals may eat less due to illness-induced anorexia, or perhaps those with chronic illness receive more health advice and may therefore consume more fruit and vegetables. By excluding deaths within a year of baseline, we attempted to address reverse causality.

Fruit and vegetable consumption was significantly associated with reductions in cancer and cardiovascular disease mortality, with increasing benefits being seen with up to more than seven portions of fruit and vegetables daily for the latter. Consumption of vegetables appeared to be significantly better than similar quantities of fruit. When different types of fruit and vegetable were examined separately, increased consumption of portions of vegetables, salad, fresh and dried fruit showed significant associations with lower mortality. However, frozen/canned fruit consumption was apparently associated with a higher risk of mortality.

Link: http://jech.bmj.com/content/early/2014/03/03/jech-2013-203500.full


"In humans calorie restriction doesn't have the same dramatic effect on longevity as it does in mice - we'd have noticed by now - but it does produce a dramatic improvement in measures of health."

Well it's calorie restriction with optimal nutrition. Until modern times it's been impossible for the optimal part to take place particularly at the more extreme levels of 40-50%.

Even the prior generation of okinawans are unlikely to be practicing more than light or moderate restriction given their smaller body size and I'm not sure they're not deficient in any micro-nutrient.

Even amongst those in modern days using software and careful intake of food, some disregard supplementation which may yield deficiency if vegetables or food have suboptimal or deficient quantities of some micro-nutrients.

Even using supplements I've heard some don't digest or are absorbed properly(don't know what truth there's to this), so even with this optimal nutrition may elude humans.

It would've been nice to have Calment's genome accessible. A tragedy, don't think anyone thought to preserve tissue in a way to conserve dna quality for further research. I suspect she may or may not have had a mutation in CR related genes, at 122 years and still some say died from choking not natural causes, there are few known genetic pathways mutations that could've aided such longevity in higher mammals.

I still think the most extreme CR such as 60% cannot possibly ever take place in a natural environment because of the very high likelyhood of lack of optimal nutrition. Either it is an artifact of natural selection's effects on more moderate CR extending beyond selected parameters or CR itself is an artifact of something else.

Posted by: Darian S at April 2nd, 2014 10:38 AM

I think Calorie restriction has merit, as a tool to reset insulin sensitivity in a person who might be at risk of type 2 diabetes without medications. But as a general treatment to slow old age by more than a few years, I am not 100% convinced, because its a bad idea to put so much stock in mouse models.
There are severe criticisms of them in the scientific literature. For example

You are also not going to get a handle on Epigenetic effects counter acting Caloric Restriction, or transforming Caloric restriction into an avenue for a host of other physiological disorder, if you use animal models too far from our primate origins

Also what concerns me is the state of mental awareness you are at when
calorie restricted. I have read that once a living animal get too far into lower weight, physiological changes occur that diminish, their senses.

I would ask the question, if you are calorie restricted and
and it takes longer to solve a problem, heal an injury (visible or not), and wind up being susceptible to more infections per year, possible behavior changes, than a non-calorie restricted individual, shouldn't the trade off value be clear and measureable directly?
I mean if you are going to live on the edge of your Minimum caloric intake for the rest of your life, shouldn't you know what you are gaining with some accuracy. Or are you willing run the experiment on yourself to see what happens?

Posted by: Rob Flores at April 2nd, 2014 1:13 PM

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