Aspirin is the most widely used drug in the world — 100 billion tablets are consumed annually. It was taken to the Antarctic by Captain Scott, to the top of Mount Everest by Edmund Hillary and to the Moon by the Apollo astronauts. Closer to home, you’ll also probably find it in every GP’s bag, since it is a known life-saver in the event of a heart attack. For most of the 20th century, it was considered one of the most successful painkilling and anti-rheumatic drugs, yet many people seem reluctant to use it. Sometimes this is due to reported side-effects such as gastric irritation and stomach ulcers. For others, the fact that aspirin is so readily available without the need for a doctor’s prescription, and so cheap, has made them regard it as little more than a household remedy and assume it is of less benefit than a more expensive tablet. The fact is that this small, white, unassuming tablet could be a veritable life-saver. Low-dose aspirin has been shown not only to reduce the risk of a second heart attack, but also a variety of other conditions including Alzheimer’s disease, depression and various cancers. It’s also thought to have a role in reducing the risk of complications in diabetes. Aspirin appears to work by reducing inflammation in the body that damages cells and tissues. It does this by preventing the action of two enzymes in the body called COX-1 and COX-2, which normally spark inflammation. However, another role of COX-1 is to protect the stomach and intestines from stomach acid damage, hence the side-effects of aspirin which include gastric bleeding, stomach ulcers and heartburn. So should you be taking a daily aspirin? To help you decide, I have looked at the research from more than 60 studies, covering hundreds of thousands of patients and a range of conditions. (Remember, you should never start taking a daily aspirin without first consulting your doctor.) Here is what I’ve found... CANCER The idea that aspirin can play a part in preventing some cancers has emerged from several lines of research. For instance, at the end of last year two major papers published in The Lancet (involving  more than 20,000 patients followed for 20 years) showed the overall cancer death rate was reduced by 34 per cent after five years of aspirin use. Studies suggest the effect might be due to aspirin’s ability to reduce levels of inflammation and COX-2. Raised levels of COX-2 have been found in cancerous tissue, and animal studies have shown that treatment with COX-2 inhibitors reduced tumour formation and growth. The risk reduction was greater in certain cancers, in particular gastrointestinal, for which death rates were reduced by 54 per cent. The Lancet studies also found a 20 per cent drop in deaths from prostate cancer, 30 per cent for lung cancer, 40 per cent for colorectal cancer and 60 per cent for oesophageal cancer. Another study, of 37,000 women and published in the International Journal of Clinical Practice, suggested aspirin use could reduce the risk of breast cancer by 20 per cent. A separate study of more than 4,000 women, published in 2010, suggested that in patients with breast cancer, aspirin reduces the risk of the cancer spreading by 43 to 60 per cent, and there was also a 64 to 71 per cent reduction in the risk of breast cancer-related death. The bottom line: Taking aspirin long term is linked to an overall reduction in the risk of several cancers, with the following points worth noting: * The effect takes five years to become apparent, though the longer the usage, the greater the reduction in risk: 20 to 25 years of usage gives the best protection. After that, there may be more risk of haemorrhages; * Low-dose aspirin — 75mg —  seems enough to produce the effect; * The peak time to start in order to reap the benefit seems to be when patients are in their late 40s and 50s; * When it comes to breast cancer, there is not yet enough research to suggest that well women should put themselves at risk of having an aspirin-related bleed in order to reduce their risk of breast cancer, nor is its use as a treatment for breast cancer patients recommended. Some researchers believe depression and inflammation might be linked after small studies showed some people with depression have high levels of cytokines — naturally occurring inflammatory chemicals. As an anti-inflammatory drug, aspirin might, therefore, be able to prevent depression or reduce its intensity. One study followed 386 women for ten years — 22 developed depression after the age of 50. Only one of this depressed group had taken aspirin, said the researchers writing last year in the Journal of Psychotherapy and Psychosomatics. But in the group who hadn’t developed depression, almost a third were taking it. The authors concluded that there is a highly significant reduction in risk of depression from taking aspirin. The bottom line: There is not yet enough evidence to say you should take aspirin to reduce the risk of depression, but the idea is certainly worthy of further research. But never combine aspirin with antidepressants without first consulting your doctor, as they can interact and increase the risk of bleeds.