Vitamins: A Threat to Our Immune System?
The increasing awareness about health and the fast rising rate of chronic illnesses have made vitamin supplements one of the largest industries today. Millions of people worldwide take supplements daily, with the hope of becoming and staying fit. But new research by the University of Oslo suggests that there’s also a darker side to some vitamin supplements.
“We believe that antioxidants are good for us, since they protect the cells from oxidative stress that may harm our genes. However, our bodies have an enormous inherent ability to handle stress. Recent research results show that the body’s responses to stress in fact are important in preventing our DNA from eroding. I fear that the fragile balance in our cells can be upset when we supplement our diet with vitamin pills” said Hilde Nilsen, the lead investigator at the Biotechnology Centre, University of Oslo, to the research magazine Apollon.
DNA is a molecule that encodes the genetic instructions used in the development and functioning of all known living organisms and many viruses. Essential as it is, the DNA is always, almost constantly exposed to damage. In each of the hundred trillion cells in the body, over 200,000 instances of damage to the DNA take place every day due a variety of factors like smoking, exposure to environmental pollution and radiation, and stress. Nevertheless, DNA damage is more often a result of the natural and life-sustaining processes that take place in the organism.
So how does the repair of DNA promote long and healthy life?
For the study, Nilsen and her team looked at the DNA structure of the Caenorhabditis elegans – a one millimetre-long nematode which lives for only 25 days. This very small roundworm is surprisingly unique as it has 20,000 genes (humans have only a couple of thousands more). Using this sample, the researchers were able to easily change the subject’s hereditary properties, and monitor what happens when the DNA damage is not repaired. According to Nilsen, different “repair proteins” take care of various types of damage to the DNA. The most common ones are repaired by ‘cutting out’ and replacing a single damaged base by itself or as part of a larger fragment.
In some specimens that don’t have the ability to repair DNA damage, the researchers observe that the ageing process takes place faster than normal. The reason for this is that the damage accumulates in the DNA and prevents the cells from producing the proteins needed for their normal operation. But Nilsen doubts this theory.
One of the genes examined by the researchers has a somewhat shortened lifespan. On average, the mutant lives three days less than normal. In humans, it means dying at the age of 60 rather than 70.
”We were surprised when we saw that these mutants do not in fact accumulate the DNA damage that would cause aging. On the contrary: they have less DNA damage. This happens because the little nematode changes its metabolism into low gear and releases its own antioxidant defences. Nature uses this strategy to minimize the negative consequences of its inability to repair the DNA. So why is this not the normal state? Most likely because it comes at a cost: these organisms have less ability to respond to further stress ‒ they are quite fragile.” The research team, for the first time, has shown that this response is under active genetic control and is not caused by passive accumulation of damage to the DNA, as has been widely believed.
“This provides an opportunity to manipulate these processes. And that’s exactly what we have done: we have re-established the normal lifespan of a short-lived mutant by removing other proteins that repair damage. Hence, the cause could not be accumulation of damage, since there is no reason to assume that a mutant with no other alternative ways to repair its DNA will be less exposed to damage. There must be something else.” Further tests led them to find out that this unknown repair agent was actually the other repair proteins, inhibiting damage that they fail to repair completely.
“We have found several proteins that trigger this reprogramming. The process has the same effect as a reduction in caloric intake, which we know helps increase the lifespan in many species. In other words, there are two routes to a long life. When we stimulate both of these two routes in our nematode at the same time, we can quadruple its normal lifespan,” Nilsen said.
The balance between oxidants and antioxidants is crucial to the human physiology, but exactly where this equilibrium is situated varies from one person to the next.
“This is where I start worrying about the synthetic antioxidants. The cells in our body use this fragile balance to establish the best possible conditions for themselves, and it is specially adapted for each of us. When we take supplements of antioxidants, such as C and E vitamins, we may upset this balance,”
“It sounds intuitively correct that intake of a substance that may prevent accumulation of damage would benefit us, and that’s why so many of us supplement our diet with vitamins. Our research results indicate that at the same time, we may also cause a lot of harm. The health authorities recommend that instead, we should seek to have an appropriate diet. I’m all in favour of that. It’s far safer for us to take our vitamins through the food that we eat, rather than through pills,” the researcher added.
Source of this article:
Vitamins in a box: Can damage the body’s own defences
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