We put this question to Professor Barry Everitt, Professor of Behavioural Neuroscience here Cambridge University.  You can read and listen to an interview with him here.

Well, what happens – if you’re going to have an addition this isn’t a bad one to have because it’s (a) quite trivial and (b) quite easy to relinquish. What happens with people who drink coffee and drink coffee very frequently is that they develop tolerance to the caffeine that’s in the coffee. As they develop tolerance to the caffeine: when the caffeine isn’t there they experience discomfort in the form of withdrawal which can be things like a headache and it can be also maybe minor mood changes but sometimes even things like palpitations that come with withdrawal from caffeine. You then take more caffeine and you have to do that more and more frequently until eventually you have a situation where people are drinking vast quantities or coffee and caffeine or tea and caffeine during the day. Then when they suddenly stop and decide to go cold turkey – it often happens to people on weekends actually, when they take coffee during the week to stay active at work and then at the weekend they tend to take less. They have headaches and they feel bad. If you just stay with that withdrawal symptom for a couple of days it disappears.

We put this question to Professor Barry Everitt, Professor of Behavioural Neuroscience at Cambridge University

It’s an interesting and good question. The answer is a difficult one to provide. What we do know is that individuals who are in withdrawal from drugs tend to have reduced levels of serotonin in key parts of the brain where the other transmitter I mentioned earlier, dopamine, is also important. There is a notion that one of the things that might cause you to take drugs again is an attempt to self-medicate, if you like, that lower level of serotonin in these key parts of the brain. That might be an interesting mechanism. Clearly serotonin is very closely linked to mood change and withdrawal induced mood change is a really quite difficult early problem for people trying to stay off drugs.

It’s both. Cells in the body are pre-programmed with a finite lifespan and a finite number of times that they can divide (split) to form daughter cells. For example, the red blood cells that carry oxygen to our tissues have a lifetime of 120 days after which they wear out and are broken down so that their constituents can be recycled. At the same time other cell types such as muscle and nerves can survive for much longer, even a lifetime, whilst the cells lining the mouth and intestines might last less than a day before being scraped off during a meal.

These cells are replaced by stem cells that divide (split) through the process of mitosis. However, scientists have found that every cell has a built-in limit on the number of times it can divide like this, known as the Hayflick number.

This occurs because the ends of the DNA chromosomes contain structures called telomeres, which are similar in some ways to the piece of tape that protects the free ends of a shoelace. Whenever a cell divides a small amount of material is lost from each telomere. Eventually, after about thirty to forty cell divisions, the telomeres become too short and the cell can no longer divide. At this stage it’s said to be senescent (aged).

Stem cells can also be forced into early senescence if their DNA becomes damaged. Switching the cell off like this is a protective mechanism to guard against cancer, which can occur when genetic changes (mutations) inappropriately activate a cell’s growth systems.

This DNA damage is usually caused by reactive chemicals called free radicals that are produced by metabolism, by toxins we take into the body in things like cigarette smoke and by exposure to sunlight. Thankfully, vitamins and other anti-oxidants help to protect cells from the effects of radicals, which is why eating a healthy diet rich in antioxidants can help to slow down the ageing process.

Nevertheless, as we age the number of stem cells capable of producing new cells to repair damage, replace lost cells and react to infections steadily declines. This means that fewer resources are devoted to repair and growth causing tissues to steadily deteriorate, and that’s why skin goes wrinkly!

Chris and Kat discussed this on the show...

Chris: Linus Paulin who got the Nobel Prize in Chemistry used to take mega doses vitamin C and he did live to be in his 90s but then so do lots of people who don’t take mega doses of vitamin C. People have done clinical trials on this to see if taking vitamin C does translate into better health. The evidence is that if you are vitamin C deficient and you get scurvy, that’s very bad, but you don’t need very much vitamin C in order not to get scurvy. Scurvy’s incredibly rare in the population now. Warding off scurvy’s probably not a good enough reason to take mega doses of vitamin C. In terms of warding off coughs and colds and things there have been a number of trials and the only one that really showed any major benefit was in Scandinavian cross-country skiers who took big doses of vitamin C. They found that with severe exercise they were slightly lower risk of catching a virus of some kind if they took the vitamin C compared with when they didn’t’ Probably, because you’re exposed to harsh conditions, cold air, your airways are getting very dried out perhaps the vitamin C helps to ward off the damage to your airways caused by those conditions and therefore reduces the risk of the airways becoming vulnerable to viral attack. Under normal circumstances I haven’t found any evidence that people are better protected if they take vitamin C.

Kat: There was also a paper I think about a year or so ago that showed actually if you take vitamin supplements you’re more likely to die.

Chris: There was one showing that vitamin E. Everyone put themselves on vitamin E thinking, ‘because this dissolves in fat perhaps it will reduce the rate at which arteries get clogged up by reducing cholesterol.’ When cholesterol is oxidised it’s more likely to block up arteries. If you take something that dissolves in fats and hence is close to the cholesterol (vitamin E) perhaps that will stop it. People who are on vitamin E started to have more heart attacks than people who weren’t so not very good news.

Chris and Kat discussed this question on the show...

Kat: What’s happening is inflammation. When you get sunburn the ultraviolet rays from the sun come in, damage the DNA in your skin. If they damage it really severely then your skin cells will die in order to protect you from cancer because your DNA’s damaged. Dying cells attract the immune system. They attract immune cells like macrophages that have to come in and eat up the dead cells. That encourages inflammation so you’ve got all these molecules called cytokines being produced. You’ve got inflammation redness, you may notice swelling as well if you get really sunburned. That’s what’s going on.

Chris: Would anti-inflammatories like aspirin make you feel better if you’ve got sunburn?

Kat: They’re help to relive the pain and they may help to take the inflammation down but of course the most sensible thing is don’t get sunburnt in the first place.

Chris: What about sunbeds? I was reading a statistic the other day. It’s a totally unregulated industry. In one case there was a set of sunbeds where the UV was five times stronger than you’d get from the noonday sun on an Australian beach.

Kat: I know and that’s a very interesting issue. In Scotland this week, in the Parliament there they’re having a debate about whether the sunbed industry should be regulated and particularly whether the sunbed should be banned for people under 18 because at that age your skin is very sensitive to this kind of damage from the sunlight and also from the ultraviolet radiation in sunbeds. At the moment, particularly in the UK sunbeds are pretty much unregulated. There’s a voluntary code of conduct from the sunbed association that parlours can sign up to but it’s not compulsory.

Chris: So they could be harmful. You could actually be doing yourself a lot of damage because, how much have they been standardised: what dose you’re getting and what it’s doing to you?

Kat: Absolutely, we would recommend people to steer clear of sunbeds generally. Especially using them excessively and do watch out because they are damaging your skin and if you overdo it you are increasing your risk of skin cancer.

Chris: And you will end up looking like a prune.