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Sunday 10 September 2017

Why caloric restriction increases longevity

Studies have been performed into ageing for more than seventy years and these reveal that caloric restriction is the most effective strategy for retarding it. But why does this work so well?

 

We take caloric restriction  to mean eating less energy dense, but not less nutrient rich foods. Caloric restriction is not to be obtained by crash dieting, or eating as little as possible for extended periods of time. Below, you will find means to work on caloric restriction in a responsible manner and obtain sustainable results.

 

Living three times longer      

Researchers from the Erasmus MC (Netherlands) found that mice that consume 30 percent less food, live approximately three times as long as their peers. For the investigation they used specially bred mice that age quicker, as they lack the genes that are necessary for DNA repair. Their results may lead to new insights in the treatment of neurodegenerative diseases such as Alzheimer’s.

 

At the start of the trial, the maximum lifespan of the mice was 6 months. The researchers then tried to increase this by using a low caloric diet. This worked: the mice that ate less lived three times as long. In addition, they retained 50 percent more nerve cells and had better motor control at a higher age than the mice that were allowed to eat in abundance.

 

“The mice that had less to eat, showed significantly less DNA damage. This was clearly visible in the nervous system”, the researchers say.

 

DNA damage and repair

DNA damage takes place in all of us, even in healthy individuals. The focal point of this damage is in slowly or non-dividing cells, such as those in the brain, skeletal muscle and the heart. It is precisely in these organs that the first signs of ageing are observed: forgetfulness, sarcopenia and arrhythmias.

 

All life-forms have biochemical mechanisms at their disposal for limiting and repairing DNA damage. This is essential for survival. Yet, preventing this kind of damage is something entirely different: however efficient the mechanisms are, there will always be some residual damage. Damage then accumulates throughout life, causing the organism to gradually become less fit.

 

When the mechanisms for DNA repair are less optimal in people, ageing also goes faster. But why do some people nevertheless become centenarians? Research shows that these people have at least one thing in common: their DNA repair protein PARP is more highly active in eliminating oxidative DNA damage.

 

So, are we just unlucky when we are not the proud owners of a highly active PARP protein? Not so fast – there are ways to limit the amount of residual damage building up and even to get rid of it. And this all starts at what – but more importantly: how much – we eat.

 

Responsible fasting

First and foremost, it is important to limit caloric intake. A good way to set about is, is to opt for intermittent fasting. This means that, of every seven days, only two are restricted to a maximum caloric intake of 300 calories; the other five one can eat anything (within reason). And this has been found to be beneficial: research shows that intermittent fasting improves the body’s resistance to oxidative stress. Oxidative stress is an important factor in ageing.

 

But there is more to the story: when one limits the number of calories in their diet, additional care should be taken to guarantee a plentiful supply of nutrients. To work properly, the antioxidant system is always in need of sufficient vitamins and minerals. Limiting calories without supplying additional vitamins only leads to accelerated ageing. Especially on fasting days it is important to take basic supplementation.

 

Why does fasting work at all?

During fasting days, the body is less taxed with oxidative stress (among other things). At the same time, repair processes in the body switch into higher gear. One of the mechanisms that increases its efficiency is the metabolic pathway of autophagy, which can be viewed as a sort of garbage disposal. Immune cells clear out damaged and non-functional proteins and protein residues that would have otherwise accumulated in the cells.

 

A number of scientists are convinced that this mechanism protects us against a number of diseases, for instance Alzheimer’s. Research carried out in rats (and monkeys) shows that intermittent fasting may extend lifespan. In one of these experiments, rats that fasted every other day lived up to 83 percent longer than those that did not fast.

 

To date, such results have not been reproduced in people, yet it seems likely to be effective; the health benefits of intermittent fasting are directly related to an improved metabolism, antioxidant defence and do show up in many health markers. All of these factors together may very well result in a longer life.

 

Intermittent fasting may not be suitable for children, pregnant women and women who are breast-feeding, the elderly and those who are underweight. 

 

Sources

Muiras ML, Müller M, Schächter F, Bürkle A (1998), Increased poly(ADP-ribose) polymerase activity in lymphoblastoid cell lines from centenarians, J. Mol. Med. 76 (5): 346–54.

Natura Foundation, 7 gezondheidsvoordelen van Intermittent Fasting, http://www.naturafoundation.nl/?objectID=12904&page=4

Vermeij WP et al., Restricted diet delays accelerated ageing and genomic stress in DNA-repair-deficient mice, Nature. 2016 Aug 24;537(7620):427-431.