Some of the things they said were good for us...

Some of the things they said were good for us

Oranges appear to ward off blindness. Researchers examined the impact of various foods on rates of macular degeneration (the most common form of blindness in older people), and found that only oranges made a significant difference: people who ate at least one orange a day were 60% less likely to develop the condition over 15 years than those who never ate oranges.

Spinach never seemed to do much for Popeye’s intelligence – but according to research reported in January, people who eat substantial quantities of leafy green vegetables are less likely to experience cognitive decline in old age. The study, involving 960 people with an average age of 81, was observational, and did not establish a causal link, but added to a growing body of evidence that certain foods are good for the ageing brain.

Being female has some advantages – one of which is that it makes you hardier, according to a study of historical death rates. This found that not only have women typically lived longer than men, they’ve also proved more likely to survive periods of hardship and disease. An international team examined data from famines in Ireland, Ukraine and Sweden, and tropical disease outbreaks in Liberia in the 1800s, and found that in almost all cases, women fared better than men. At the height of Ireland’s potato famine in the late 1840s, for instance, life expectancy for men fell to 18.7 years, but was 22.4 for women. The difference is mainly down to infant mortality rates, and could be related to the protective effect of the hormone oestrogen.

Keeping fit in middle age could be one of the best ways of warding off dementia in later life. For a study at Gothenburg University, nearly 200 women aged 38 to 60 were asked to ride on a static bicycle as hard as they could, to gauge their cardiovascular fitness, and were then placed into four groups accordingly. Four decades on, only 5% of the most fit group (of 40 women) had developed dementia, rising to 32% of those in the least fit group (of 59). Moreover, the few women in the fittest group who did develop dementia only became symptomatic aged 90 on average – 11 years later than the dementia patients among the moderately fit women.

Pasta has been unfairly demonised, we learnt in March. People have tended to assume that because it’s an unrefined carbohydrate, it is best avoided by anyone anxious not to pile on the pounds. But unlike potatoes, white bread and short-grain white rice, pasta is a low glycaemic food: it releases energy slowly and doesn’t cause blood sugar levels to spike. When researchers in Canada analysed data from 30 previous studies, they found no evidence that eating modest amounts of pasta, as part of a low GI diet, led to increased weight gain or higher fat levels; in fact, the pasta eaters often lost weight.

Saunas are not common in British homes, but if you have one, make the most of it: researchers at the University of Bristol looked at health data from Finland, and found that older people who used a sauna four to seven times a week were 60% less likely to have a stroke than those who went just once. This was so even after they had adjusted for factors such as high cholesterol, and may be because saunas seem to keep blood pressure down. But don’t worry if you don’t own a sauna: it may be that a similar effect can be achieved from a hot bath: a small study in Japan found that people who regularly have long (12 minutes or more), hot baths scored better than others on measures including stiffness of the arteries and blood pressure – though it could just be that people who find time to wallow in the bath just have less stressful lives.

Eating nuts, if you are a man trying to improve your fertility, could be a good idea: a diet rich in them appears to boost the quantity and quality of sperm, said Spanish researchers in July. In a trial, involving 119 healthy men aged 18-35, those who added 60g of mixed nuts (almonds, hazelnuts and walnuts) to their typical Western diets had, after 14 weeks, a sperm count that was 16% higher than the non-nut eaters. Their sperm also showed improved vitality, motility and morphology relative to the others.

… and some the scientists said might do us harm

Mucky duckie?

Rubber ducks are a staple of bath time in many households, but the toys are not as benign as they look. As many parents will have observed, the water trapped inside them becomes, over time, a worrying-looking sludge, and this year, scientists discovered that this substance is riddled with bacteria, some of them potentially harmful. The team speculates that if children squeeze the toys so the sludge hits their faces, it might lead to infections. But there’s no need to dump duckie: just squeeze it out after every bath.

One cigarette a day is one too many. Smokers who cut that far back may think their habit is harmless, but according to a study published in February, they still have a 50% raised risk of cardiovascular disease (roughly half that of 20-a-day smokers). “No safe level of smoking exists for cardiovascular disease,” warned the report in the BMJ.

Ultra processed food forms a huge part of the modern diet. In February, an analysis of shopping habits in 19 European countries revealed that food which has been significantly altered in a factory accounts for half of all the food bought in the UK. In the same month, a study involving 100,000 people, published in the BMJ, found that a diet rich in ultra-processed food was associated with a raised risk of cancer. This, the team said, was probably down to the “wide range of additives” it contains, and its “generally poorer nutritional quality”.

Heavy drinking is clearly a mistake, but to the risks already associated with it, we must now add another: early dementia. In March, a French study, which looked at data on millions of people discharged from hospitals from 2008 to 2013, found that 57% of the patients diagnosed with dementia before the age of 65 had been diagnosed with alcohol dependency or hospitalised with an alcohol-related condition. Heavy drinking is associated with other risk factors for dementia, such as smoking – but it clearly damages the brain, and probably has a “much larger” role in dementia than previously believed, said the study leader. As for moderate drinking, it’s hardly safe either: in April, a major study into the impact on life expectancy of light drinking concluded that having just one glass of wine five times a week robs a 40-year-old of six months of their life, on average.

Plastics, and their impact on us and our environment, were an enduring concern in 2018. In March, a team revealed that they had tested 259 samples of bottled water from nine countries, and found plastic in “bottle after bottle, brand after brand”. Typically, there were ten particles per litre the width of a human hair, and 314 smaller ones per litre. A few weeks later, marine conservationists warned that the Great Pacific Garbage Patch – a build-up of debris floating between California and Hawaii – is at least four times, and possibly as much as 16 times, bigger than previously thought, and growing “exponentially”. In October, scientists from Vienna found the first evidence of plastic in the human digestive system.

Bringing up a large family isn’t just hard work: if you’re a woman, it could affect your health. A Cambridge University study, reported in June, looked at data on more than 8,000 American women, and found that their risk of heart attack, stroke and heart failure all increased in line with how many children they had. For instance, over a 30-year period, women with five or more children were 40% more likely to suffer a serious heart attack than those with two. Pregnancy and childbirth can put a strain on the heart; but having a lot of children also means women have less time for “self care”, the researchers said.

Airborne pollution remained one of the major global health issues this year, with numerous studies warning that dangerously high levels of particulate matter are contributing to millions of premature deaths worldwide each year, including those of half a million children. In September, however, an international team warned that airborne pollution is not just a threat to people’s health: their study, which compared the test scores of 20,000 people in China with the air quality in their home regions, indicates that it also has a “huge” impact on intelligence levels.

selection of scientific theories and discoveries from 2018

The largest prime of all
The largest prime number ever found was unveiled in January, discovered by an engineer from Tennessee. It has more than 23 million digits, making it a million digits longer than the previous record holder, found in 2015. The number is known as a Mersenne, and is expressed as 2 to the power of 77,232,917 minus 1.

Expanding wine glasses
We’re not just drinking more wine than our forebears – we’re drinking it from ever bigger glasses (the phenomena may be connected). A team from Cambridge University analysed 411 wine glasses from different eras, and found that the ones we use today are, on average, seven times larger, at 449ml, than those used in the Georgian period.

Fake news travels fast
It’s what we’ve long suspected, but in March, it was confirmed that fake news travels faster online than the truth. A team from the Massachusetts Institute of Technology tracked 126,000 stories on Twitter over ten years, and found that the false ones were 70% more likely to be retweeted than the true ones, and that the true ones took six times longer, on average, to reach a wide audience (of more than 1,500). It wasn’t bots doing the spreading, they found; nor was it necessarily indicative of malign intent. Fake news may simply get spread more because people find lies more interesting – or surprising – than the truth.

Clever wasps
One wasp hovering by a picnic is almost always followed by a horde – and now we know why. In May, scientists discovered that when “scout” wasps discover a source of food, they don’t just tuck in themselves: they fly back to their colonies, and alert the troops by beating their abdomens against different parts of the nests to create a drumming sound. Previously this behaviour was thought to indicate hunger; but the team at LaGuardia Community College in New York, now reckon it’s a form of communication known as “recruitment”.

IQ levels are falling
If IQ levels are an accurate gauge of intelligence, young people today are not as clever as previous generations. Scientists in Norway analysed the scores achieved by 730,000 young men who did IQ tests as part of their national service from 1970 to 2009. They found that for many years, the IQ levels of entrants slowly rose, by about 0.3 points a year on average, but that it peaked among the cohort born in 1975, and then began to fall, at a rate of seven points per generation. It’s not clear what is behind the decline, but it could be changes to the education system.

A healthy workforce?
British workers missed an average of 4.1 days through sickness last year, the lowest figure ever recorded. Back in 1993, when the ONS started collecting data on sickies, the average was 7.2. It has been declining ever since, but it’s not clear why. Some say the population is getting healthier, but others believe that a culture of “presenteeism” – going to work when ill – has grown up, owing to insecure labour conditions.

edgehogs in trouble
Hedgehog populations are in such trouble, the creatures are now only present in a fifth of rural areas in England and Wales, according to research published in September. The proliferation of badgers since 1992, when they were given extra legal protection, could be one reason for the decline: the species compete for food, and badgers sometimes eat hedgehogs.

Dogs overrated
Dogs are not as clever as many humans think, it seems. An Exeter University team examined 300 studies on animal intelligence, and concluded that while dogs have an unusual skill set, they are not inherently smarter than other animals. For example, sheep are just as good at distinguishing humans by their faces; sea otters are better than dogs with tools; and pigeons are better at remembering events. Even dogs’ renowned olfactory powers are not that special: pigs have an equally sensitive sense of smell.

Down with meat
The pressure was on meat eaters this year, as scientists warned that the environmental impact of food production in general, and livestock farming in particular, is unsustainable. In October, a University of Oxford team said that without radical action, the planet won’t be a “safe operating space for humanity” by 2050. Among other things, it said that “flexitarian” diets, where red meat is eaten only once a week, must become the norm. Global per capita meat consumption has nearly doubled in the past 50 years.