Another week, another “superfood”.A new variety of plum is being heralded as the next wonder-food. According to a British supermarket's “food technologist” (whatever that is), the plum has ten times as much anthocyanin, which is a powerful antioxidant, as normal plums. This is obviously just marketing, but the idea that antioxidants are always good for you is one that deserves a closer look.Antioxidants are enzymes that clear our cells of harmful molecules, so on the surface, it seems reasonable that they would be good for us (there is a deeper discussion of how antioxidants work in the “Further Explanation” below). They have been shown to play a protective role in neurodegenerative diseases like Parkinson’s and Alzheimer’s, and they may lower the rate of heart disease among type 2 diabetics. Another study showed that the Vitamin E, a well-known antioxidant, could halve your chances of contracting ALS.However, as more studies have been carried out, we have seen a darker side to antioxidants. For example, a 2011 study showed that men taking Vitamin E had a 17% increased risk of developing prostate cancer (although this finding has been recently questioned). A meta-analysis carried out in 2007 suggested that far from being good for you, antioxidants increased mortality, rather than decreasing it. Furthermore, interventions that are known to increase lifespan (like calorie restriction) may no longer work if the animal is on antioxidants. The authors of that study conclude, “treatment with different antioxidants and vitamins prevents extension of life span”. Finally, a review of the human literature concluded that taking antioxidant supplements does not reduce mortality.Ultimately, the literature is very mixed when it comes to antioxidants, but one this is certain: they are not the panacea that the health food industry would have you believe. When it comes to health claims about food and drink, it’s best to stay sceptical. The old advice of “moderation in all things” is still the best we have. AntioxidantsWhen your cells produce energy, one of the by-products are reactive oxygen species (ROS). These are chemically reactive molecules that can cause damage or death of the cell. However, they also play a role in normal cellular health, so controlling their levels is of utmost importance. Antioxidants are molecules that soak up the ROS, controlling their levels, and there are multitudes of naturally occurring antioxidants that help maintain the proper balance. There are times, however, when high levels of ROS are needed. For example, one of the bodies defences against cancer is to increase the level of ROS, causing the cancer cells to die. So in theory, antioxidants could be bad for you if you have a tumour.
Smoking is even more dangerous than we realised
The UK government has finally decided to push ahead with legislation on plain packaging for cigarettes before the general election in May. This comes after years of inexcusable delay and extensive lobbying by the tobacco industry. In a brazen attempt to bully the government, the tobacco companies have even threatened to sue for damages if such legislation is introduced. Plain packaging is already required in Australia (and is now being introduced in Ireland) and has been shown to be an effective anti-smoking measure (evidence of which can be found here, here, here and here).We are all fully aware that smoking is one of the most dangerous activities that you can do, but recent work has emphasised just how dangerous. Two studies (one in the New England Journal of Medicine, the other in BMC Medicine) have shown that smoking is associated with more diseases than previously thought, and plays a role in far more deaths. The first study was carried out in Australia, and followed over 200,000 people for 4 years to assess the effect of smoking on their lifespan. This was a well carried out, prospective study (see below for explanation). They found that death rates in smokers were 3-times higher than in non-smokers, and that smokers die an average of 10 years before their non-smoking counterparts. Furthermore, up to 67% of deaths in smokers can be attributed to their habit. To put it simply, for every three people you see smoking outside a pub, two of them will eventually die from a smoking related illness if they don’t quit. It’s a shocking toll.The second study was a meta-analysis (see below for explanation) of 5 previous US studies, including nearly a million people. They showed that at least 30 diseases are associated with smoking, including cancers of almost every site (pancreas, bladder, breast, kidney...). It’s a terrifying list, which I have included below, but there is some good news. The BMC Medicine study confirmed that if somebody stops smoking, not only will the damage stop accumulating, but the body can begin to heal itself. The earlier the smoker quits the better, and those who quit early have the same lifespan as non-smokers.These studies emphasise the need for continued efforts to reduce the levels of smoking. Measures such as the plain packaging of cigarettes, and the banning of smoking in cars are positive steps. The UK government's vote on the issue before will take place before May, so hopefully there will be progress soon. Fingers crossed.https://twitter.com/CRUK_Policy/status/573898151842701312Diseases associated with smokingLaryngeal cancer - 103.8 times more likely to die from than non-smokersLung cancer - 22.9Lip and oral cavity cancer - 5.6 Oesophageal cancer - 5.1Urinary bladder cancer - 3.9Pancreatic cancer - 1.9Liver cancer - 1.8Stomach cancer - 1.7Colorectal cancer - 1.6Breast cancer - 1.3Kidney and renal pelvis cancer - 1.2Acute myeloid leukaemia - 1.1Rare cancers - 1.1Cancers of unknown site - 2.7Chronic obstructive pulmonary disease (COPD) - 25.0Aortic aneurysm - 10.1Ischemic disorders of the intestine - 6.1Other arterial disease - 5.6Ischemic heart disease - 3.0Liver cirrhosis - 2.6Infection - 2.5Hypertensive renal disease - 2.4Unknown causes - 2.2Stroke - 2.1Atherosclerosis - 2.1Other digestive diseases - 2.1Additional rare causes - 2.0Other heart disease - 1.9Pneumonia, influenza, and TB - 1.9Hypertensive heart disease - 1.9Other respiratory diseases - 1.9Renal failure - 1.9 Diabetes - 1.5Further ExplanationProspective study: This is the gold standard of medical studies. In a prospective study, people are recruited to look specifically at a certain thing (in this case, the effect of smoking on lifespan). The study is planned ahead of time, and controls are put into place to ensure the highest quality data. This differs from a retrospective study, where data that has already been gathered is analysed to draw conclusions about a certain outcome. This type of study can be prone to significant bias, because unlike a prospective study, you cannot control the population you are studying. It is also more difficult to separate correlation from causation using a retrospective study. It is far easier and cheaper than a prospective study however, and very often the only option.Meta-analysis: This type of study involves the combining of several studies in the hope of revealing patterns in the results of those studies. A meta-analysis allows the study of far larger numbers of people, but can be severely affected if one or more of the individual studies is poorly carried out.
